This lecture is to call to mind this great pioneer of high-speed photography and cinematography, who would have been 90 years old a few weeks ago. In addition to his career, his various scientific contributions, his interests, and his far-sightedness in scientific cooperation, personal experiences also are mentioned.

Recent advancements in the Ultranac camera are described. The camera incorporates all solid state electronics which are used to drive the all metal/ceramic image converter tube. Individual exposure and inter-frame times are fully programmable via an external computer. A review is made of the applications in which Ultranac is being employed -- these include combustion studies, particle flow, ballistics and detonation phenomena.

This paper reports the results of a study that empirically determined the gating time of an MCPI tube must be about eight times more than the iris time to prevent spatial resolution degradation. During the study, MTF curves were taken under dc conditions, as well as dynamic gating conditions from 1.6 microsecond(s) to 1 ns gate widths on a tube that has an iris time of 1.2 ns. Under dc conditions, the 50% MTF was 10 lp/mm; under dynamic conditions, the 50% MTF was 7 lp/mm from 1.6 microsecond(s) to 20 ns FWHM. However, when the gate width was reduced to 10 ns, the resolution began to decrease and became 5 lp/mm at 1.0 ns. The results of the experiment and the MTF measurement apparatus are discussed.

A totally new approach has been taken to develop an image intensifier for use in front of high speed rotating prism and image converter cameras at framing rates up to 1 million pictures per second. Cinemax II is a high brilliance image intensifier which can also record UV radiation down to 180 nm, increasing the scope of the automotive engineer investigating the combustion process. Cinemax II is gated on at a frequency of 100 Hz to facilitate setting up and wide aperture critical focussing. Variable gain allows the image brightness to be adjusted to satisfy different subject lightning conditions. In operate mode the gate on period can be readily synchronized to the event and camera to ensure optimum results are achieved and safety thresholds are not exceeded. Cinemax II has successfully been used with the Imacon 792, Photec, and Hyspeed cine cameras for combustion and plasma research.

Common high-speed gated proximity focused multichannel plate image intensifiers allow for a typical gate width of 3 to 5 ns. We have studied an alternative way to accomplish sub- nanosecond time-resolved imaging by operating a gatable proximity focused intensifier as a radio-frequency phase-sensitive camera. In this operating mode, we apply a dc bias voltage between the photocathode and the microchannel plate input that brings the effective intensity transfer function to 50% relative to the `ON' state. Then we add a rf signal to the dc voltage which is phase-locked to the intensity modulation phase of the imaging light source. This phase-locking causes a steady-state image at the intensifier output screen which is recorded using a CCD camera, and stored in an image processor. At least two images are recorded at two different intensifier modulation phase settings relative to the light source modulation phase. Finally, the two images are subtracted, or divided, pixel-by-pixel to create the time- resolved image. The rf phase-sensitive camera has been applied to distance-selective image suppression. We have created black-and-white contrasts for target distance differences of 3.75 cm, i.e., for photon transit time differences of 0.25 ns. The camera also can be used to accomplish lifetime-selective fluorescence suppression.

The current demand for inexpensive streak camera manufacturing leads to the necessity in development of a variety of relatively simple and low cost image-converter tubes. One such tube, known as PIF-C, designed and manufactured in the Photoelectronics Department of the General Physics Institute (GPI), is now commercially available. Its experimentally measured time resolution in streak mode has approached one picosecond, and 3 ps in synchroscan mode at 82 MHz operation frequency. In single frame mode at 100 ns exposure time, the spatial resolution over 6 mm input area is within 15 lp/mm. Electron optical magnification of the tube is 1.5 ^x. PIF-C tubes may be supplied with one of the S1/S20/S25 photocathodes, fabricated either on borosilicate glass, UV-glass, or MgF₂ substrate. Its P11 phosphor screen is deposited onto the fiber optic window. EBI of the PIF-C/S1 tube is in the range of 5 (DOT) 10^-10 A/cm².

Obtaining detailed photographs of the early stages of the first hydrogen bomb explosion in 1952 posed a number of problems. First, it was necessary to invent a continuous-access camera which could solve the problem that existing million-picture-per-second cameras were blind most of the time. The solution here was to alter an existing camera design so that two modified cameras could be mounted around a single high-speed rotating mirror. A second problem, acquiring the necessary lenses of precisely specified focal lengths, was solved by obtaining a large number of production lenses from war surplus salvage. A third hurdle to be overcome was to test the new camera at an A-bomb explosion. Finally, it was necessary to solve the almost impossible difficulty of building a safe camera shelter close to a megaton explosion. This paper describes the way these problems were solved. Unfortunately the successful pictures that were taken are still classified.

A new electronic control system provides intelligent (computer) control features for high speed film cameras. This system incorporates the most significant advances made since the advent of analog servo controls in high speed cameras a generation ago. All of the camera's former electronics are replaced with digital electronics operating under 32-bit microprocessor control which directs and monitors each camera function. Typical camera control functions include selection of: camera operating speed, phase-lock synchronization, shutter phasing delay in multiple-camera installation, film load, acceleration time, etc. Entries are made on a keypad, on the camera housing, or may be made by an external data link. Keypad inputs are displayed on a 16 character liquid crystal display (LCD) located adjacent to the keypad panel. A 15- character LED numeric display, at the edge of the film aperture, prints the IRIG-B time code on film, or real-time data supplied via an RS232 input from sensors associated with the test or process being filmed. This data can also be stored in a RAM memory so that it precisely matches the numerically recorded information on each frame of film. The stored data can then be downloaded to an external computer for analysis, thereby speeding the data reduction process and eliminating the likelihood of human error in reading frame-by-frame film data.

Exposure time reduction with rotating prism cameras is usually achieved with narrow angle shutters, or slits. Exposure times of 1 microsecond are possible with this low cost method, but there are disadvantages: (1) Vast amounts of continuous lighting are required to produce a correctly exposed film, even with the fastest materials available. (2) Total frame recording time remains constant for a given setting. `Focal plane' distortion occurs, particularly with extremely fast events, although subject movement is `frozen.'

With SST and with its variations in BiSST, OSST, or especially with BiOSST the characteristics of a shaped charge jet, such as tip velocity, length, particulation times and distances, diameters, transverse velocities, tumbling rates, and 3-D jet deviations, can be fully analyzed. All this can be done quantitatively with high accuracy. Observation of the jet surface under bright front illumination provides new insight into its structure under very high strain rates during extreme elongation.

By combining the attributes of electro-optic shuttering and pulsed laser illumination in a large format camera system, we have developed a multi-frame image converter camera with a laser illuminator that produces sequential photographs of fast phenomena with very high resolution. The combination of the large size image plane (75 mm), short exposure time per frame (minimum 12 - 15 ns), and monochromatic laser illumination provides clear, sharp, front-lit images of surfaces and shapes with no degradation by luminous air shocks or motion blur. The unique modular design of the camera and the laser allow for a variety of configurations and applications. The current camera system produces eight independent pictures or four stereo pairs. A Q-switched ruby laser with multiple pulse capability provides individual illumination for each frame. This system has photographed a variety of fast phenomena including the first stereo sequential photographs of the initial formation and early time history of high velocity shaped-charge jets.

High-speed photography at framing rates of up to 1 million per second has been employed to investigate the mechanisms of initiation of an explosion and its propagation in a small arms cartridge. Specially designed models have been used to simulate the conditions inside the cartridge and the photography has been carried out using reflected light. It is found that the impact of the striker pin on the percussion cap of the cartridge causes several reaction sites lying close to the impact axis and it is argued that these sites are located at intergranular frictional hot spots in the primary explosive composition. It is also shown that the reaction from the cap to the main propellant charge is transmitted by the streaming of the hot reaction products of the former into the grains of the latter.

A PV001 streak image tube supplied with an atmosphere resistant (AlMgCu)O_x photocathode is reported. Quantum efficiency of such a photocathode being irradiated by 5 ps light pulses at 354 nm wavelength is up to 10^-3. It is shown that this photocathode may be exposed for many cycles (> 20) of air admittance without losses in its quantum efficiency. It is believed that the PV001/oxide tube may be used in electron diffraction experiments.

Cameras and laser illuminators have been upgraded and combined into a coaxial streak and frame system. The argon laser illuminating the streak camera over the duration of the event is combined with the short pulsed dye laser for stop motion framing, using a polarization splitter. The combined beams are sent to the target, viewed by the same objective lens, then split by a second polarizing splitter and relayed to the appropriate cameras. A half-wave plate before the second splitter allows adjustable levels of light of each laser to be leaked to the opposite camera for fiducial purposes. A particular advantage of this arrangement is that both the laser beams are tailored and aimed separately. The dye laser is spatially filtered and focused to cover the frame. The argon laser is focused to a line on the target which is then imaged to the streak camera slit. The ability to see the focal line of the argon laser on the frame camera allows precise collocation of the fields of view of the two cameras.

This paper discusses a laboratory method based on generating a buoyant thermal cloud through explosively bursting an aluminum foil by a rapid electric discharge procedure. The required electric energy is stored in a bank of capacitors and is discharged into the foil through a trigger circuit on external command. The aluminum first vaporizes and becomes an aluminum gas plasma at high temperature (approximately 8000 K) which then mixes with the surrounding air and ignites. The cloud containing these hot combustion products rises up in an unstratified anechoic environment. As the cloud rises, it entrains the air from the surroundings due to turbulent mixing and it grows. To characterize this cloud rise, three different types of photographic techniques are used. They are: high-speed photography (6000 fps), low-speed photography (200 fps), and video photography (30 fps). These techniques cover various time scales in foil firing schedule beginning from early time (up to 10 msec) to late time (up to 4 secs). Images obtained by video photography technique have been processed into a digital format. In digitizing the video tape data, an optical video disk player/recorder was used together with pc-based frame grabber hardware. A simple software routine was developed to obtain cloud size/rise data based on an edge detection technique.

The work of two types of optical fiber gauges on the basis of polymeric light guides was developed and investigated for registration of x,t-diagrams of shock waves movement in solids, liquids, and free surfaces of moving bodies. End-type gauges are proposed for self- luminous phenomena registration. For investigating phenomena in the low-pressure range we used loop gauges. The results of investigations of the gauges' work in gas-dynamic experiments are presented.

An experimental technique for investigating the air flow passing a domestic electric fan by using flow visualization and high speed photography is reported in this paper. A rotary-prism type high speed camera and a motion analyzer were applied in the experiments to investigate the flow pattern closely neighboring the fan blades. The smoke emerged from dry-ice was used as the trace particles. The particle paths and some significant flow phenomena in the flow field were then clearly observed. On the basis of the results obtained by use of this technique, significant improvement over the existing ceiling fan blades has been made for some dozen manufacturers in both mainland China and Hong Kong, resulting in great benefits.

For the precise observation of high-speed impact phenomena, a compact high-speed streak camera recording system has been developed. The system consists of a high-pressure gas gun, a streak camera, and a long-pulse dye laser. The gas gun installed in our laboratory has a muzzle of 40 mm in diameter, and a launch tube of 2 m long. Projectile velocity is measured by the laser beam cut method. The gun is capable of accelerating a 27 g projectile up to 500 m/s, if helium gas is used as a driver. The system has been designed on the principal idea that the precise optical measurement methods developed in other areas of research can be applied to the gun study. The streak camera is 300 mm in diameter, with a rectangular rotating mirror which is driven by an air turbine spindle. The attainable streak velocity is 3 mm/microsecond(s) . The size of the camera is rather small aiming at the portability and economy. Therefore, the streak velocity is relatively slower than the fast cameras, but it is possible to use low-sensitivity but high-resolution film as a recording medium. We have also constructed a pulsed dye laser of 25 - 30 microsecond(s) in duration. The laser can be used as a light source of observation. The advantage for the use of the laser will be multi-fold, i.e., good directivity, almost single frequency, and so on. The feasibility of the system has been demonstrated by performing several experiments.

For investigations of fast nonstationary events, e.g., flows, injection jets, etc., the high speed cinematography is particularly suitable, but there are difficulties with 3-dimensional motions. First the paper deals with problems and objectives which arose during the development of a new drum camera that is also suitable for high speed holography. The result is a drum camera for up to 200,000 f/s, also for use with holograms. The camera set-up and first test results are described, and possibilities of further developments are shown.

A mirror-rotating type compact streak camera whose maximum streak rate was faster than 10 mm/microsecond(s) and a strong Xenon-flash lamp with a wide flash area were produced for impact- shock study of solids. The streak camera mainly consists of the high-frequency motor with an air bearing of 120,000 rpm in a maximum rotating rate, the square-shaped mirror, the lens system with a 15 micrometers -width slit, and the circular-shaped film mount case of 830 mm in inner diameter. The flash lamp consists of two parallel Xenon tubes of 40 mm in length and 10 mm in diameter, which were stimulated with two high voltage condensers of 100 (mu) F and 2 kV. The shock-wave measurement experiments of solids in several 10 s of GPa region were performed by the inclined-mirror method using the streak camera and flash lamp in combination with the keyed-powder gun.

Increasing frame rates and the sensitivity to heat of test objects has forced the development of improved lighting systems. In response to the need for better high speed lighting systems, several advances have been made over the last few years. The primary one is the conversion to the use of metal halide arc lamps instead of tungsten halogen incandescent types. This was followed by the development of electronic power supplies to drive these lamps. The EPS in conjunction with the lamps can provide flickerless light with the capability of accurate power control. This paper presents the key points in this development and describes some of the features of practical `boost lighting systems' presently in service at several test sites. It also describes some of the advantages that will be available in the future with the addition of computer control functions to these systems.

A high pressure arc lamp capable of producing over ten million lumens is presented. The arc's unique cooling allows this type of arc to operate at continuous power ten times greater than any other. Spectral data is presented that shows a white light continuum with strong near infrared spectral lines. Continuous operation and millisecond pulses are outlined. Examples include a 3 by 5 meter area illuminated to 400 klux and a 6 m diameter parabola that produces a 2 degree beam angle and a peak of 4 billion candle power.

Developments in the design of image converter camera systems are reviewed. Designs of image converter tubes are discussed. Final image capture by photographic film and CCD camera and analysis systems are considered.

A high-speed imaging device has been built that is capable of recording several hundred images over a time span of 25 to 400 ns. The imager is based on a streak camera, which provides both spatial and temporal resolution. The system's current angular resolution is 16 X 16 pixels, with a time resolution of 250 ps. It was initially employed to provide 3-D images of objects, in conjunction with a short-pulse (approximately 100 ps) laser. For the 3-D (angle-angle-range) laser radar, the 250 ps time resolution corresponds to a range resolution of 4 cm. In the 3-D system, light from a short-pulse laser (a frequency-doubled, Q-switched, mode-locked Nd:YAG laser operating at a wavelength of 532 nm) flood-illuminates a target of linear dimension approximately 1 m. The returning light from the target is imaged, and the image is dissected by a 16 X 16 array of optical fibers. At the other end of the fiber optic image converter, the 256 fibers form a vertical line array, which is input to the slit of a streak camera. The streak camera sweeps the input line across the output phosphor screen so that horizontal position is directly proportional to time. The resulting 2-D image (fiber location vs. time) at the phosphor is read by an intensified (SIT) vidicon TV tube, and the image is digitized and stored. A computer subsequently decodes the image, unscrambling the linear pixels into an angle-angle image at each time or range bin. We are left with a series of snapshots, each one depicting the portion of target surface in a given range bin. The pictures can be combined to form a 3-D realization of the target. Continuous recording of many images over a short time span is of use in imaging other transient phenomena. These applications share a need for multiple images from a nonrepeatable transient event of time duration on the order of nanoseconds. Applications discussed for the imager include (1) pulsed laser beam diagnostics -- measuring laser beam spatial and temporal structure, (2) reflectivity monitoring during pulsed laser annealing of microelectronics, and (3) detonics or shock wave research, especially microscopic studies of shocks produced by laser pulses.

An experimental prototype of a femtosecond streak image converter camera was built around a specially designed femtosecond streak image tube having a cylindrical type electron focusing lens. Experimentally measured temporal resolution of the camera is better than 500 fs while its spatial resolution is not worse than 40 lp/mm across the slit direction.

A new model of a Scancross-type streak tube is proposed. It can be useful in studies of short light flashes aimed at elucidation of not so much spatial as temporal light flux energy distribution. The Scancross tubes differ from their predecessors in that photoelectrons escaping a 40 mm photocathode surface are gathered in an aberration-free crossover due to an electrostatic field formed by a special `quasispherical' electron-optical system. At the crossover output, the electron beam aperture is compressed, whereupon the beam is accelerated and focused onto the phosphor screen plane. The focusing system field also performs an anisotropic transformation of a point crossover, i.e., compression of the latter's image on the screen in the scanning direction with simultaneous crosswise extension. A rectangular crossover image in the form of a 0.035 mm X 3 mm dash was obtained with the screen size of about 40 mm in the scanning direction. Sensitivity of the high-frequency deflection system was 25 V/mm. A strong compression of the electron beam emanated from the photocathode enabled a 4 orders of magnitude brightness magnification. Employment of such a streak tube allows a much more simple oscilloscope optical system for collection of radiation to be used, since there is no longer need for a small-dimension focusing spot on the photocathode as when using conventional streak tubes. This also simplifies detection of electromagnetic radiation in a very wide spectral range. Calculations suggest the possibility of extending the detection dynamic range by at least two orders using special signal procession accounting for light distribution both in the scanning direction and crosswise.

As a part of the joint research projects between General Physics Institute and Yonsei University/V.TEK Company, an experimental prototype of an image converter camera is designed and manufactured. The camera operates both in single frame and single shot streak modes. Single frame exposures are varied in the 250 - 1000 ns range, while recording intervals in streak mode are adjusted within the 2 - 1000 ns range over a 25 mm-wide output screen area. Temporal resolution at maximum streak speed is better than 10 ps. Total camera gain is 5 (DOT) 10⁴. The camera is equipped with a specially designed PIF-V.1 image converter tube. Available are choices among S1, S20, or S25 photocathodes fabricated onto Molibden glass/UV glass, or MgF₂ substrate.

Photocathodes based on In_0.53Ga_0.47As/InP heterostructures (HS-photocathodes) with Schottky barriers for a spectral range of 0.9 - 1.6 micrometers were investigated. The maximum external quantum yield was 0.5% at (lambda) equals 1.5 micrometers and dark current was I_ed equals 3*10^-8 A/cm². It has been shown that in such photoemitters under reverse bias of about U equals 30 V, the electric field completely penetrates into the working layer of the photocathode. Since the dark current does not depend on the value of the reverse bias, HS-photocathodes may be used for time analyzing tubes to record picosecond pulses with milliwatt peak intensity. To increase the signal/noise ratio we suggest using InP/In_0.53Ga_0.47As superlattice (SL) for designing a SL-photocathode with internal amplification.

Low-jitter reliable short-duration spark sources have been developed for application in color schlieren methods. With an Xe-filling of a previously used nanosecond spark source (NANOSPARK 1400), the light quantity could be increased up to tenfold while the pulse width rose up to 500 ns depending on gas pressure. When filled with air, the new extended version NANOSPARK 4000, which is about three times the size of the NANOSPARK 1400, exhibits pulse widths of 50 - 80 ns (FWHM) and BCP five times as large as the smaller version. With an Xe-filling, the light quantity is again magnified by a factor of ten, but also the pulse width goes up to 900 ns depending on gas pressure. These sources have adequately exposed customary ASA 400 film in various color schlieren experiments. Moreover they have been used in a shearing interferometer and in several monochrome visualization setups.

The fundamental studies for the flash vacuum-ultraviolet (VUV) source utilizing a surface- discharge substrate are described. This flash VUV source consists of the following essential components: a high-voltage power supply, a polarity-inversion-type high-voltage pulser with a condenser capacity of 14.3 nF, an oil diffusion pump, and a flash VUV chamber with a glass body. The VUV chamber employed a surface-discharge ferrite substrate that's pattern was formed by means of the copper vacuum evaporation and was connected to an oil diffusion pump with a pressure of 1.3 X 10^-3 Pa. The combined ceramic condenser in the pulser was charged from 10 to 30 kV by a power supply, and the electric charges in the condenser were discharged to the radiation chamber after closing a gap switch. Then the flash VUV rays were generated. The maximum values of the cathode voltage and the tube current were about -21 kV and 1.7 kA, respectively. The VUV outputs were measured by a combination of a plastic scintillator and a photomultiplier. The pulse durations of the VUV rays were nearly equivalent to the durations of the damped oscillations of the voltage and current, and their values were about 10 microsecond(s) .

A simple technique for obtaining sinusoidally modulated laser radiation, of which the modulation period can be smoothly varied in the range from hundreds of femtosecond to tens of picosecond, is described. The idea of this method consists in the use of linear frequency modulated laser radiation when each axial mode has the same linear chirp.

This paper describes the EMI ruby laser stroboscope and two examples of its application, the study of behind the armor effects of a KE-projectile and the initiation of HE (high explosive) by a hypervelocity debris cloud. The flash x-ray technique is the common method to visualize terminal ballistic and impact phenomena which are mainly combined with light flashes, dust, and fragment clouds. The laser stroboscope is a useful completion to the other techniques, it allows the visualization of long duration (1 ms) events with high-time resolution and high accuracy. At a frequency of 200 kHz, for example, about 260 frames are taken with the camera at exposure times less than 20 ns.

An illumination system is developed for a microscope with a newly developed straight-type Xe flash tube as the light source. An optical fiber is used as the light transmitter to connect the microscope and the light source. The axis of the fiber is coincided to that of the plasma excited in the Xe flash tube. The efficiency of the light beam injected to the fiber is improved up to 5 times of that of the conventional type illumination system.

A novel powerful strobe for high-speed photography is described which can replace the high power cw light source, to save energy and synchroflash with the camera. In this strobe, three- phase transformerless direct rectifier, high current SCR switch and pre-ionization technique are used so that the energy consumption goes down greatly, and its total weight is less than 25 Kg. Its principal parameters are as follows: average power, 50 KW; light emitting pulse width, 1 - 100 ms; pulse rise time, less than 0.05 ms; pulse fall time, less than 0.1 ms.

Usefulness of holographic interferometric flow visualization applied to shock wave research is presented. Reflected shock transition from Mach to regular reflections over wedges is discussed in detail. Examples of shock wave reflection from curved wedges are presented in conjunction with the shock transition phenomena.

The imaging of high velocity (> 2000 m/s), 7 mm Cuboids impacting on various targets is discussed. The reasons why conventional H.S. Cine techniques, even framing at 40,000 pps, are inadequate to record the detail required are outlined. Four different methods of image capture are illustrated giving a direct comparison between state-of-the-art technologies.

A relatively simple method is explained, which makes it possible to determine the detonation velocity of an infinitely large charge, using a very small size sample. However, this requires additional instrumentation and a simple trick in the design of the sample. A prerequisite for this is that the detonation velocity of a reference high explosive must be known accurately and that this velocity is larger than that of the high explosive to be examined. By observing the front face, the true detonation velocity can then be determined, even with a very small sample size. The theoretical background, test set-up, and execution of the experiments are described below. Beside this special application, sandwiched explosive charges are of general interest in connection with shaped charge design, and generally in the effort to increase the efficiency of explosive energy transmission.

The Engineering Department at Oxford University has a history of designing, building, and operating its own devices. Highspeed photography has been no exception. This paper looks at the progression from novel home built rotating mirror cameras through the building of a 9 spark Cranz-Schardin dynamic photoelastic bench, including a typical test and a sequence of photographs using this equipment, to results from an in depth study into the dynamic behavior of a new material, super-plastically formed sandwich panels using the Cordin 377 camera.

Experiments are described where normal impacts of caliber 7.62 mm projectiles on ceramic faced steel plates were observed by high speed photography. Three kinds of ceramic tiles in size were used, and they were bonded to a 10 mm thick backing of strong steel plates. When the target was a steel plate alone, a core of M2 AP projectile has easily passed through the target and the core has been almost intact. The ceramic facing has had two effects on the penetrator effectiveness in this case, one due to blunting of the core tip and the second due to removal of the core mass in erosion. Because of these two effects, the defeated core has been far less effective at penetrating steel plate than that of the intact core. We have obtained minimum safe facing composition with each adhesive.

A new procedure is proposed of generating converging or of colliding shock waves in solids. The method is based on the refraction phenomena of a plane shock front at a shaped material interface, due to the difference in shock velocity of the materials of each side. A high-pressure gas gun is used to produce plane shock waves in a composite target assembly. The assembly is composed of aluminum and of polyethylene. The conically converging shock wave is generated in a lower-impedance material, i.e., polyethylene. In this case, polyethylene material is machined to the shape of a cone, and is inserted and glued to the aluminum plate having just the same inner surface. The processes of shock convergence are observed by a compact high-speed streak camera together with a pulsed dye laser as a light source. We have performed a series of experiments by varying several parameters. The realized converging angle of shock waves is found to be about 55 - 60 degrees in polyethylene medium. It is shown that the converging wave front looks almost continuously curved, and it is not easy to discriminate the boundary of the Mach stem. In other words, the growth of the Mach region seems faster than expected. This result is attributed to the combined effects of wave convergence and Mach reflection.

Multiflash photography is a simple, economic, and efficient technique for the research of desert physics. The study of the micro-characteristics of sand blown by the wind in the desert is one of the basic subjects in desert research. The research on this gas-solid two phase flow was conducted using high speed multiflash photography both in the environment sand wind tunnel and in the natural desert environment for studies of the flight trajectories of moving by jump of sand grains and the structure of wind-blown sand. The experimental results indicate the moving trajectories of sands by wind presents the form of opposite parabola. The taking- off angles have linear relation with the descending angles. The distribution function of the sand content of the wind-blown sand is verified through the statistical analysis.

A configuration for sequential holographic recording based upon a new system for obtaining a train of spatially separated light pulses at frequencies ranging from 6 MHz to 35 MHz has been developed. The multipulse system uses a high energy Q-switched Nd:YAG laser as a light source,and incorporates a phase-front preserving optical delay line and a specially graded beamsplitter to produce up to ten spatially separated light pulses of nearly equal energy. The temporal spacing between successive output pulses may be varied discretely in increments of 28.3 ns from 28.3 ns to 169.8 ns. The system is currently used for high-speed time-resolved holography of dynamic events with lifetimes between 100 ns and 1.5 microsecond(s) . Other applications include using the system either as a single point or `phased-array' source for laser generation of ultrasound.

The interaction of laser radiation with materials can lead to the generation of thermal and acoustic transients. If the laser pulse is of short duration and high power as in the case of a Q switched Nd YAG laser, then shock waves may be formed with fast rising pressure fronts. The optical diagnostics of laser generated sound waves therefore requires high spatial, approximately 10 micrometers , and high temporal, approximately 10 ns, resolution, in order to make quantitative measurements. A nitrogen laser pumped dye laser with a pulse length of 0.4 ns has been used as the light source for a Mach-Zehnder interferometer. The interferometer was modified to enable dynamic photoelastic interferograms to be taken. Recording was by means of a CCD video camera and computer controlled digitizing frame grabber. This system has been employed to study laser generated waves at water-polymer boundaries and the diffraction of ultrasound by defects in the solid material. The isochromatic fringe patterns, together with an approximate Abel inversion procedure, allow the radial pressure distribution in the polycarbonate test samples to be calculated. The ultimate aim is to obtain the near field diffraction coefficients for use in NDT modeling.

A noncontact shock (or acoustic) pulse detection system has been developed using optical probing of the refractive-index change associated with the pulse. The pulse profiles are monitored by the transient photorefractive deflection of collimated He-Ne probe laser beams. An increase in sensitivity of detection is achieved by an angular magnification of the deflection by refracting the deflected laser beam through a peripheral section of a converging lens. The transient deflection is observed by using a knife-edge to block half of the probe beam and detecting the deflection signal with a fast photodiode. By using two or more probe beams at different displacements from the pulse source and detecting their deflection at different times, the pulse velocity and attenuation in the medium can be determined. A demonstration of the capability of this system is made by the velocity measurements for shocks in a tube and for spark generated sound pulses in various media such as gas, liquids, and solid. Results agree well with those obtained by conventional technique. The proposed technique is superior to the conventional methods in that it is noncontact and easily applied to any hostile environment.

For a given flow field obtained in a shock tube several visualization techniques are applied to reveal both the weak and the strong points of each individual method. Particular emphasis is put on two newly developed schlieren techniques, which prove to be most suitable for a detailed optical investigation of a large number of problems in fluid mechanics.

A color schlieren system, which accurately indicates density gradient directions, has been developed. This system differs from the classical schlieren system by replacing the dark/bright regions on a uniform background with colored regions, each color representing a gradient direction. A component description of the system is given, with the formation of the color schlieren image being explained. The new system is compared to other color schlieren techniques, and photographs of schlieren tests are included.

In this paper shearing interferometry as used at the Prins Maurits Laboratory for studying shock wave diffraction around structures is reviewed. The performance of the shearing interferometer is illustrated by a number of applications. It is shown that, for not too complicated flow geometries, accurate density distributions of the flow field can be obtained from an analysis of the recorded interferograms. A comparison of results obtained with a numerical code, based on the flux-corrected transport (FCT) method, and experimental data also are presented.

We briefly describe the origin, history, and present status of pico/femtosecond image converter photography in Russia to which the late Professor Boris M. Stepanov devoted his talent, knowledge, and life. Taking into consideration the scientific background toward the end of the forties to the beginning of the fifties, we show why this field of technology has attracted people and resources, who was involved in this activity, where R&D work and manufacturing facilities were established, and when and how this area was developed. The present level of pico/femtosecond image converter photography is described in general and future trends are outlined.

The use of a high-speed (up to 100 MHz) programmable pattern generator and special clock driver/translator circuits for clocking solid-state multiple output imagers is discussed. A specific example of clocking a developmental 256 X 512 two-port CCD is illustrated. Reference to a prior report of clocking an eight-port CCD is included. Future use in clocking a CID imager is discussed.

A new optically deflected streaking camera with performance of nanosecond-range resolution, superior imaging quality, high signal detectability, and large format recording has been conceived and developed. Its construction is composed of an optomechanical deflector that deflects the line-shape image of spatial-distributed time-varying signals across the sensing surface of a cooled scientific two-dimensional CCD array with slow readout driving electronics, a lens assembly, and a desk-top computer for prompt digital data acquisition and processing. Its development utilizes the synergism of modern technologies in sensor, optical deflector, optics and microcomputer. With laser light as signal carrier, the deflecting optics produces near diffraction-limited streak images resolving to a single pixel size of <EQ 25 micrometers ². A 1kx1k-pixel array can thus provide a vast record of 1,000 digital data points along each spatial or temporal axis. High signal detectability is expected from the combined advantage of sharp focusing, 75% QE 514 nm of a thinned backside-illuminated CCD, absence of any undesirable signal conversion involving diffusing emission or inefficient coupling, and low noise of CCD readout electronics. Since only one photon-to-electron conversion exists in the entire signal recording path, the camera responses linearly to the incident light over a wide dynamic range in excess of 10⁴:1.

The characterization of a 512 by 512 pixel, eight-output full frame CCD manufactured by English Electric Valve under part number CCD13 is discussed. This device is a high- resolution Silicon-based array designed for visible imaging applications at readout periods as low as two milliseconds. The characterization of the device includes mean-variance analysis to determine read noise and dynamic range, as well as charge transfer efficiency, MTF, and quantum efficiency measurements. Dark current and non-uniformity issues on a pixel-to-pixel basis and between individual outputs are also examined. The characterization of the device is restricted by hardware limitations to a one MHz pixel rate, corresponding to a 40 ms readout time. However, subsections of the device have been operated at up to an equivalent 100 frames per second. To maximize the frame rate, the CCD is illuminated by a synchronized strobe flash in between frame readouts. The effects of the strobe illumination on the imagery obtained from the device is discussed.

The Edwards-Duromedics (ED) mechanical heart valve prosthesis is of a bileaflet design, incorporating unique design features that distinguish its performance with respect to other mechanical valves of similar type. Leaflet motion of mechanical heart valves, particularly during closure, is related to valve durability, valve sounds and the efficiency of the cardiac output. Modifications to the ED valve have resulted in significant improvements with respect to leaflet motion. In this study a high-speed video system was used to monitor the leaflet motion of the valve, and to compare the performance of the Modified Specification to that of the Original Specification using a St. Jude Medical as a control valve.

Immediately after the launching of VCR in VHS Format by JVC for consumer use in 1976, NAC has also started to work on development of VCR in VHS Format for the first time under the licensing arrangement with JVC, and has succeeded in the development of a special type VCR in VHS Format in 1979 which is durable in the special severe environment required for the airborne use. NAC has worked on development of High Speed Video System by utilizing the technologies acquired from the development of VCR in VHS Format. NAC has then introduced in 1981 HSV—200 Sytem for the first time in Color as High Speed Video System. This HSV—200 SystemU is capable of recording at 200 fields per second with scanning lines of 262.5 lines per field based on the VHS (NTSC) Video Tape Standard. Since this has allowed to use the standard VHS video cassette, this System has provided the various merits; it has lowered its operation cost and the video cassette recorded by HSV—200 System has become possible to playback on the standard VCR of VHS Format for consumer use. This basic concept has been carried on all the subsequent models NAC developed to this date. Based on HSV—200 System, NAC has announced a serie of different models; FHS—200 specially designed for field use in 1982, HVRB—2002) designed for airborne purpose in 1983, and MHS—200 for use with a microscope in 1986. The recording speed of these models are all 200 fields per second and these models have been conveniently used for various applications in the new and different sectors of High Speed Video Instrumentation market. In 1987, a new feature of 400 fields per sçcond in half size was incorporated into HSV—200 System and a new model, HSV—4003) with field memory and various kinds of playback modes was announced. In 1990, HSV—l0004) System was introduced. This model is capable of recording at 500 fields per second in full size and at 1000 fields per second in half size. The VCR of HSV—l000 System has been adopted with new feature to handle S—VHS Format in addition to the current VHS Format and it has realized much higher resolution. The camera has also been improved by changing the imaging device from the current image pickup tube to the solidstate MOS Image Device and it has successfully reduced the lag practically to Zero of which resulted in a great improvement of Dynamic Resoluti on. In 1991, HSV—5005) System in S—VHS Format was developed, as the successor of HSV—400 System, based on the technologies cultivated at HSV—1000 System. HSV—500 System is capable of recording at speed of 250 fields per second in full size and 500 fields per second in half size in S—VHS/VHS Formats. HSV—500 and HSV—l000 Systems now have become the main product lines of NAC in the recent years. Followings are the major steps taken for the technological development of new features and functions of NAC High Speed Video Systems

High-speed, high x-ray energy imaging of implosions is a key diagnostic technique in the glass laser implosion program in the USA. With the correct x-ray energy, time-gated images can measure the symmetry and mix of the imploding shell into the stagnated fuel if the spatial resolution of 10 or 5 micrometers matched by a temporal resolution of 100 or 50 psec. Several 100 psec microchannelplate (MCP) x-ray pin hole cameras have bee installed and run on large laser systems with improving reliability. To increase the sensitivity of the imaging system, a ring aperture microscope has been coupled to a gated MCP detector allowing imaging at up to 8 keV.

High resolution x-ray streak cameras using tubes with bilamellar electron optics have been developed for a long time in CEL-V, in collaboration with Philips Components (now Philips Photonics) for the tubes. The last improvements on their electronics, implemented on the commercial cameras developed with ARP, have allowed us to get the best results from the tubes, especially for the quality of their focusing. We have already been able to verify that the performance of the C850X camera in the UV range is as good as expected from calculations. New experiments made in the x-ray range show that it is also true in the x-ray range. We describe the results of these experiments and we also show preliminary results obtained with the C750X camera (which is identical to C850X except that its deflection structure is a meander travelling wave line instead of conventional plates) which show that the sweep speed reached gives us a 1 ps temporal resolution in the x-ray range.

The heating and the sounding pulse are generated by the same laser. The laser output radiation is split into two independent channels, one of them is converted into an ultraviolet picosecond pulse by means of backward stimulated scattering. When a 3 - 10 ns pulse is produced by a Q- switched laser, the temporal compression of the sounding pulse is performed with a cascade Brillouin and Raman backward stimulated scattering. When a 0.1 - 1 ns pulse is produced by a mode-locked laser, the sounding pulse compression is achieved with a backward stimulated Raman scattering. The beam is then frequency-doubled into 315 nm in a BBO crystal. The ultraviolet pulsewidth is about 10 - 20 ps and its energy is larger than 0.2 mj.

The soft x-ray time-resolved spectroscopy is composed of a soft x-ray spectroscopic head and a soft x-ray streak camera. Because the soft x-ray spectroscopic head possesses a spectral resolution of 0.1 angstrom, the performances of the whole system mainly depend on the characteristics of the soft x-ray streak camera. In this paper, therefore, the design features and characterization of the soft x-ray streak camera are mainly described. In order to record the spectrum ranging from 30 angstroms to 230 angstroms on a limited photocathode slit length, the whole camera including the photocathode can be shifted along the spectrum without dismantling the camera from the soft x-ray generating chamber. The soft x-ray streak image tube possesses a specially designed vacuum-tight valve, which could be closed or opened in the vacuum chamber operated by a step motor, to prevent the photocathode sensitive to soft x- ray and internal intensified microchannel plate from pollution by water vapor or dust in the atmosphere. In order to test its dynamic performances, a soft x-ray diode was developed. The dynamic testing shows that the temporal resolution of this camera is 5 ps, which is limited by our soft x-ray source, dynamic spatial resolution is 20 lp/mm which implies the spectral resolution of 0.25 angstroms. Because of using CsI or KI photocathode deposited on a 1000 angstrom thick parylence film, the spectral responses range is approximately 0.05 to 10 KeV.

Results of the tests of the universal image converter camera operating at streak and three- frame modes are described. Transition to the modular construction principle of the image converter tract makes it possible to design the 2-nd camera modification with flexible architecture that can be easily, and in the best manner, adapted to requirements of the concrete experiment. Camera construction and the testing methods are described.

A new synchroscan streak tube PV250 is designed with a three-electrode focusing system and two low inductance electrostatic deflection systems having thick inputs (of approximately 4 mm in dia). Efforts were made to diminish the metal effect, especially on the photocathode side, for metal is gas producing which spoils infrared sensitivity. The accelerating electrode is a 0.1 mm width slit or fine mesh of 5 mm in diameter. The image-converter magnification is 1.5 and the working diameter of the phosphor screen is 25 mm. The scanning system is characterized with deflection sensitivity of 0.05 mm/V, capacitance of 4 pF, and resonance frequency of 450 Mcps. Results of dynamic tests are given and the tube's characteristics are compared with those of the Hamamatsu camera.

The review covers the period comparable with a history of HSP Congresses. Agriculture, textile industry, fluid mechanics, combustion and plasma physics applications are mentioned and some information about HSP equipment, including home-made, is also given. The accompanying video and a long list of references are aimed to present a general view of HSP state-of-the-art in Poland.

Video motion analysis has entered a new era with the introduction of the Kodak Ektapro EM Motion Analyzer, high-speed solid-state video recording system. No longer confined to many of the environmental and technical limitations of high-speed tape drive systems for image acquisition, the electronic memory solid-state recorder offers new recording schemes never before possible. This paper focuses on innovative recording techniques of this new, innovative ruggedized digital video recorder.

This paper presents the Palsys multi-imaging system, the recent history of the development of the system, and its component instrumentation as well as basic theory and practices of operation. The Palsys consists of the Palflash Short Exposure Pulsed Flash Unit; the Palseq, a four channel delay generator; the Palstor Video/Computer Framestore; the video CCD camera; long distance microscope or other suitable lens; and the Pals Computer Software. The Palsys can measure speed, size, distance, and angles to a very close tolerance of particle sizes, down to 15 microns at speeds of 15 m/s. The modular design of the Palsys allows for extreme system flexibility to achieve the desired results. The Palflash has uses in spray atomization, ballistic, detonics, schlieren studies, shadowgraph, etc.

We have developed a prototype of a fast-scanning CCD readout system to record a 1024 X 256 pixel image and transport the image to a recording station within 1 ms of the experimental event. The system is designed to have a dynamic range of greater than 1000 with adequate sensitivity to read single-electron excitations of a CRT phosphor when amplified by a microchannel plate image intensifier. This readout camera is intended for recording images from oscilloscopes, streak, and framing cameras. The sensor is a custom CCD chip, designed by LORAL Aeroneutronics. This CCD chip is designed with 16 parallel output ports to supply the necessary image transfer speed. The CCD is designed as an interline structure to allow fast clearing of the image and on-chip fast shuttering. Special antiblooming provisions are also included. The camera is designed to be modular and to allow CCD chips of other sizes to be used with minimal re-engineering of the camera head.

A previously developed electronic high-speed back-lighted camera based on the Cranz- Schardin principle has been improved. The new model of the camera system can operate in the front-lighted as well as in the back-lighted mode. The sequence of high resolution, full screen frames can be stored and processed by computer.

The inherent property of the frame-transfer CCD to shift simultaneously the charge distribution from the pixel matrix of the sensor site into the storage region is used for high- speed imaging. Technical details of the method and some practical applications to the visualization of evaporating liquid jets, propagation of desorption waves, and time-resolved spectra are presented.

The Los Alamos National Laboratory has constructed and is now operating a cineradiography system for imaging and evaluation of ballistic interaction events at the 1200 meter range of the Terminal Effects Research and Analysis (TERA) Group at the New Mexico Institute of Mining and Technology. Cineradiography is part of a complete firing, tracking, and analysis system at the range. The cine system consists of flash x-ray sources illuminating a one-half meter by two meter fast phosphor screen which is viewed by gated-intensified high resolution still video cameras via turning mirrors. The entire system is armored to protect against events containing up to 13.5 kg of high explosive. Digital images are available for immediate display and processing. The system is capable of frame rates up to 10⁵/sec for up to five total images.

Six kinds of repetitive flash x-ray generators having hot-cathode radiation tubes with maximum repetition rates of kilohertz (kHz) to megahertz (MHz) are described. These generators were primarily designed in order to increase the repetition rate of flash x rays and to perform cine or multiple-shot radiography. The temperatures of the filament (cathode) had values of about 2000 K for increasing tube currents. Because the hot-cathode triode was quite useful for high-voltage switching with high-repetition rates, four types of generators in conjunction with the grid pulsers were developed.

The construction and the fundamental studies for the repetitive flash x-ray generators designed by Japan Impulse Laboratory in Iwate Medical University are described. These generators are classified to the following two major types: (1) generators having diodes, and (2) generators having triodes. In order to generate high-voltage impulses, we employed the following transmission lines (pulsers): (a) high-voltage-inversion type with a maximum output voltage V_om of about 80 kV, (b) high-voltage- inversion type having a coaxial cable (V_om equals 130 kV), (c) two-stage Marx pulser (V_om equals 150 kV), (d) two-cable-type Blumlein (V_om equals 120 kV), (e) modified Blumlein (V_om equals 120 kV), (f) fundamental transmission line for triode (V_om equals 100 kV), and (g) transmission line for an enclosed triode (V_om equals 100 kV). Using these generators we succeeded in performing high-speed radiography as follows: (a) delayed radiography; (b) multiple-shot radiography; and (c) cineradiography.

The dynamic processes of many very fast phenomena are obscured by secondary by-products of the event. Consequently investigation by conventional photographic techniques cannot be satisfactorily employed. To record these events cine x-ray systems have been used with considerable success penetrating the smoke, plasma, and dust which otherwise would totally obscure detailed recording of the process. As more and more very fast dynamic processes are subject to critical investigation effective photographic based recording requires exposures considerably less than those currently available. By combining nano second flash x-ray sources and the Imacon 792 framing camera it has been possible to sequentially record events with velocities up to 8 kilometers/second and still maintain an effective common viewpoint.

A high speed readout imaging system utilizing a commercial flash x-ray machine and miniature x-ray detectors has been developed. This system was designed to operate in the environment near a nuclear detonation where film or camera imaging cannot be used. The temporal resolution of the system is set by the 20 nanosecond FWHM of the x-ray pulse. The spatial resolution of the system was determined by the size and close packing of the PIN diodes used as the x-ray detectors. In the array used here, the PIN diodes have an active area of 2 mm in diameter and were placed 3.8 mm center to center. Computer-generated images using algorithms developed for this system are presented and compared with an image captured on film in the laboratory.

SPECTRA is a personal computer-based application software system which effectively supports our research work on the flash x-rays. It consists of four program modules: (1) data- entry function, (2) energy spectra calculation function, (3) spectra curves displaying function, and (4) image simulation function. Data of tube voltage and tube current from the flash x-ray source can be entered either through the data-storage units automatically or by manual input operation. Calculation of energy spectra is based on Kramers' equation. Source date and the results of calculations can be saved in the external storage. Saved data can be used as input data of the above functions (3) and (4). In function (4), under the specified conditions of voltage, current, and the x-ray absorbers, the intensity of the x rays which permeate a given physical body model is calculated for its every subdivided part and its simulated radiographic image is displayed on the CRT screen.

The potential of the high speed electronic flash and the stroboscope to significantly contribute to the fields of science and technology cannot be overemphasized. Important applications for these instruments and applied techniques have been described by Dr. Harold Edgerton and elaborated upon by numerous other workers. This paper presents a summary of some of these projects. They are presented here to not only gratefully acknowledge the direct connection to Dr. Edgerton's pioneering work but also to re-emphasize the usefulness of specific electronic flash and stroboscopic analysis techniques.

In order to generate well defined photochromic grids needed in complex flow analysis, we are developing a multi-stage nitrogen laser to produce UV beams with high intensity and low divergence. The objective of this paper is to present our preliminary results that include the generation of a 6 X 6 photochromic grid together with a description of the analysis scheme used to determine the velocity and vorticity fields.

This report concerns the design of four types of sealed off gas-filled high-pressure spark gaps providing subnanosecond jitter when triggering them by nano- and picosecond laser pulses focused onto the cathode.

Possibilities for practical application of the optical level method in material spall strength measurements (in addition to its traditional field of application -- shock compressibility of matters) have been studied on copper as an example. Design formulae corresponding to the case of a wedge-wise sample and sliding detonation of explosive as the way of loading are given. Results of copper spall strength measurements obtained by the optical level method are presented, analyzed, and compared with other authors' data.

Infrared images of jet impingement are used to evaluate the effectiveness of heat transfer due to an air jet from a nozzle striking a surface. A unique Heat Transfer Jet Impingement Facility (HJIF) has been designed and constructed for testing nozzles. The nozzles to be tested are mounted in the facility. The performance of the nozzles at various flow and operating conditions is evaluated from infrared images and computer codes. The experimental apparatus and the operational procedures for the utilization of the infrared images are described. This unique application of infrared imaging as a research and development tool for determining air nozzle performance at steady state conditions has been found to be generally superior to earlier approaches.

Detailed measurements of the time dependence of the neutron flux from the implosion of DT- and/or DD-filled targets are required to better our understanding of inertial confinement fusion. Past efforts at developing fast neutron detectors have generally suffered from a lack of sensitivity and/or insufficient time resolution. In this paper we report on a new streak camera diagnostic for directly time-resolving the neutron burnwidth for ICF implosions. The technique uses the (n,p) reaction in CH₂ to convert the neutron signal to a proton signal, which is proximity coupled to a CsI secondary electron emitter and is subsequently recorded with a standard LLE large-format x-ray streak camera. An x-ray signal is recorded simultaneously with the neutron-produced signal and provides an accurate timing fiducial for burn-time measurements. We have recorded usable signals from the implosion of DT-filled targets producing yields of 3 X 10 ¹⁰ neutrons, with a target to photocathode distance of 30 cm. The calculated time resolution is better than 20 ps for 14 MeV neutrons and 10 ps for 2.45 MeV neutrons. Our technique for recording the neutron flux can also be extended to high-speed framing cameras, currently capable of 35-ps-duration gate times. The framing cameras will permit the simultaneous recording of the burnwidth and the neutron energy spectrum. Also, time-resolved neutron imaging of the core will be possible for DD yields > 10¹².

This report concerns the design of two types of interchangeable devices intended for pulse illumination of fast-running processes operating with one and the same six-frame Krantz- Shardin camera of which they are a part.

New motion analysis systems provide the capability to record images of high-speed events in a digital format. By downloading this digital image data to a computer workstation, users can perform numeric analysis with greater speed and accuracy. Image data can also be shared with other computer-based applications and/or distributed to other users without degradation in image quality. This paper focuses on the practical use of motion analysis workstation software specifically designed to support the archiving, display, enhancement, and analysis of digital, high-speed images.

We present in this paper an image processing system to analyze and to detect some defects on metallic caps in movement with a speed of ten caps per second. We explain in detail the image acquisition method, the choice of the process parameters (in particular an edge detection parameter), the software development compatible with a micro computer (486 33 Mhz), and the working explanation of this system. We propose another solution which is more performant in words of processing time and image resolution. This solution uses an ASIC device that we have developed and which operates the real time edge detection (25 images per second). This work has been performed in relation to an industrial contract.

The PI-74C hand-held computer is loaded with 70 programs having 95 selection entries for instrumentation photographers and engineers concerned with high speed photography. The programs perform numerous calculations applicable for use with high speed cameras of the intermittent movement and the rotating prism designs as well as for continuous film-flow cameras for streak and synchro-ballistic work, high speed video, illumination, and for velocity analysis.

An automatic three dimensional particle tracking technique has been applied to the study of particle motion in a modeled flow field. Equipment used for this technique is a high speed video recording system, Kodak Ektapro 1000, with two cameras arranged relatively orthogonally to take sequential pictures of fluid particle motion in two different views. Two fluid dynamic properties derived by this automatic three dimensional particle tracking technique are presented in this paper. These properties are particle residence time and particle acceleration.

Both (continuous wave and high average power pulsed) multi-kW IR-gas lasers spark growing interest in research and industrial applications. In the pulsed mode improvements of the thermo-mechanical energy coupling efficiencies are provided by nonlinear effects due to surface plasma formation. Experiments with single pulse HF- and CO₂-lasers are covering fluence ranges up to more than 100 J/cm². A 3 kW CO₂ laser additionally was operated in the repetitively pulsed mode up to 100 Hz. Target materials comprise highly reflecting metals as well as absorbing dielectric materials including optical transparencies. In these studies, fast electrical, electro-optical, and optical diagnostic methods were applied (electrical probes, optronical devices, optical fibers, high speed cameras, and laser diagnostics). Experiments are revealing the usefulness of simultaneously applying these multiple purpose high speed diagnostic methods for obtaining quantitative information and for controlling and optimizing the energy transfer rates.

A new optical commutator switch, capable of very high speed pulse generation and pulse multiplexing/demultiplexing, is proposed. It consists of an integrated optical Y-branch modulator and a `cul-de-sac' microstrip resonator. A possible compound digital optical modulator, using these optical commutators, is described. The results of measurements made on a cul-de-sac resonator, fabricated on an alumina substrate, and on optical Y-branch modulators, fabricated on z-cut lithium niobate substrates, are presented. For the resonator the unloaded quality factor was measured. For the optical Y-branch modulators the on/off ratios and percent guided powers were measured as functions of the applied voltage for several branch angles. The results indicate that optical commutators, of the type proposed, could be made.

Precise timing for x-ray bursts is crucial in acquiring useful information from flash radiographic experiments. Triggering the flash x-ray system near the muzzle is a difficult task because of the intrinsic nature of the muzzle blast. In this work a compact and reliable triggering method for near muzzle flash radiography is introduced; a piezoelectric pin probe attached at the end of the barrel. These types of probes have not been activated by the precursor shock wave, but they have been activated by the main blast wave only. Reliability in triggering the flash x-ray system has been confirmed throughout a series of flash radiographic experiments near the muzzle for gun barrels with calibers up to 105 mm.

A Cranz-Schardin camera with independently adjustable inter-frame times from 100 microseconds to less than 1 microsecond is described. The flash system is the classical LC spark and delay approach used by Cranz and Schardin. The capacitors are 0.06 microfarad units charged to only 7000 volts, allowing the use of commercially available flash lamp trigger transformers as delay inductors for the longer times. Shorter delays are achieved with homemade vacuum potted coils. The field element may be a telescope achromat, a Fresnel lens, or alternately a concave mirror. The camera lenses are standard achromats or simple meniscus lenses sold by optics supply houses. Mounted on the lensboard of a Calumet 4 inch by 5 inch view camera, the optics train is simply installed in the camera. The front end of the camera may be raised to bring the lens apertures into position to act as schlieren stops. Photos of resolution charts are shown to demonstrate the camera.

The paper reports the research results on the phenomenon of elastic unstableness in martensite transformation of Cu-Al-Ni shape memory alloy (SMA). We use the method of micro-high speed photography. The martensite of Cu-Al-Ni SMA presents thermoelastic strain in the heating and cooling process. While the sample is heated to A_s, the martensite begins to contract and the temperature reaches A_f point, the martensite is gradually reducing. It is possible that the martensite suddenly disappears from certain visible size at the instant it is heated to A_f temperature.

The requirements for obtaining phase conjugation due to stimulated Brillouin-scattering of CO₂-laser radiation in high pressure gases have been investigated. The steady state gain factors and the phonon lifetimes for different gases at 10.6 micrometers were calculated. Simply focussing a pulsed TEA-CO₂ laser beam up to power densities near below the gas breakdown threshold proved not to be sufficient for initiating the stimulated Brillouin scattering process. With a special oscillator amplifier setup and feedback system it was possible, however, to overcome these constraints so that for the first time measurements of stimulated CO₂-radiation back-scattering in various gases can be reported.

A new circular-scan streak camera based on a PV006S image converter tube (ICT) is proposed. Circular scan of 40 mm in diameter at 492 MHz with 17 W of rf power consumption was obtained. The camera temporal resolution of 5.5 ps in cw mode was measured. The developed camera may find application in laser ranging, photochemistry, etc.

We have improved the gain uniformity of sealed microchannel plate image intensifiers (MCPIs) by selectively scrubbing the high gain sections with a controlled bright light source. The major contributor to poor uniformity on most of the tubes we have tested is the cathode, with the MCP and screen making only minor contributions. Using the premise that ions returning to the cathode from the MCP damage the cathode and reduce its sensitivity, we raster scanned an HeNe laser beam light source across the cathode of an MCPI tube. Cathode current was monitored and when it exceeded a preset threshold, the sweep rate was decreased 1000 times, giving 1000 times the exposure to cathode areas with sensitivity greater than the threshold. The threshold was set at the cathode current corresponding to the lowest sensitivity in the active cathode area so that sensitivity of the entire cathode would be reduced to this level. This process reduced tube gain by between 10% and 30% in the high gain areas while gain reduction in low gain areas was negligible. Effects on cathode spectral sensitivity and phosphor efficiency, the results of including the MCP in the feedback loop, the possibility of reclaiming tubes damaged by prolonged exposure to resolution targets, and circuit details are discussed.

A complete procedure for computer modeling of static and dynamic performances of numerous electron optical systems is described. Basic equations for estimation of electromagnetic field distribution inside electron optical lens are presented. Use is made of aberration analysis for estimation of electrons trajectories and their transit times. On the basis of the developed (tau) -variations technique, integral parameters of various electron optical systems may be precisely evaluated. A short description of the developed software package is given together with some examples of its application for different image tubes computation.

An experimental prototype of a fully automated streak camera was designed on the basis of an image tube equipped with a back-side electron bombarded (EB) charge-coupled device (CCD). The developed camera temporal resolution is not worse than 5 ps at a recording dynamic range on the order of 100, and the overall system spatial resolution is 40 lp/mm at 10% MTF. The camera operation mode, its streak speed, and processing of the temporally dispersed image are controlled by a computer.

On the basis of theoretical and experimental study a new picosecond and nanosecond framing camera has been developed. The details associated with the design features of a framing image tube and its controlling circuitry are outlined and the experimental results obtained with this camera are shown in this paper. Recently experimental results have shown that this camera can provide 25 lp/mm, 17 lp/mm and 12 lp/mm with the exposure time (FWHM) of 5 ns, 250 ps, and 77 ps for each of 3 framing images, respectively. The pulse circuit for 6 frame images has been developed and the camera equipped with this circuit is being further tested. It is expected to obtain the same performances as stated above. This camera also can be used as a picosecond streak camera.

Dealing with dynamic behavior of solids, flows, detonator initiation, high explosive properties, shock waves, and other fast processes involves many metrology problems. In this communication, we classify various techniques according to the kinematic or thermodynamic parameters that we need to improve our knowledge of detonics problems. They are primarily: spacial observation of the phenomena versus time, chronometry of events, material densities, and boundaries detection by radiography.

Laser polymer surface ablation is used in a variety of materials applications. However, little is known about the fundamental mechanisms of laser ablation. We have developed a model ablation system, consisting of a near-infrared (near-IR) dye embedded in a polymer, where the mechanism of ablation is purely photothermal. This system has been studied in detail using ultrafast optical microscopy. Dyes which function as molecular optical thermometers have been embedded in the polymer, permitting the use of precise optical calorimetry to study its thermal decomposition. The practical applications of this model system in imaging science, where it is used in high speed formation of high-resolution, high fidelity, and dry color images, are discussed.

Several optical diagnostic techniques are used to evaluate the dynamic response of materials to intense dynamic loading and unloading, high stress and strain, and pressure. Velocity interferometry and electronic streak photography, each with sub-nanosecond time resolution, are used to record dynamic material response. Laser-launched flat plates are accelerated to 10¹² m/s² with terminal velocities > 5 km/s. By impacting these plates into target samples, high strain rates (10⁸ sec^-1) and pressures > 100 GPa have been generated for a duration of 0.8 - 5 nanoseconds. The efficacy and limitations of each technique are detailed and applications to other fields discussed.

We describe and demonstrate a system for creating `snapshots' of instantaneous 3-dimensional flow structures in turbulent flows and flames. An image converter camera operating at 10 million frames per second provides up to 20 frames of planar flow visualization at successive planes within the flow. Coupled to the image converter by fiber optics, a slow-scan CCD camera records the image converter output as a single CCD image. Successive flow planes are visualized by scanning a laser sheet through the flow with visualization by particulate scattering or laser-induced fluorescence. In previous papers, we have described the system requirements and initial results. In this paper, we provide empirical characterization of the system hardware and a selection of instantaneous 3-D measurements.

Recent works in the authors' laboratory are reviewed on construction and application of a dual focus high speed camera, a modified Cranz-Schardin camera. This paper first describes the camera system and then applications to several kinds of dynamic fracture tests and a ball impact test.

The dynamic elastic stress between two blast holes was investigated by means of high speed moire photography in order to find out the mechanism of crack generation and propagation. From sequences of moire patterns the curves of (sigma) (t) at different positions between two holes were obtained which shows that the stress at the midpoint of the two holes is always obviously smaller than that on the wall of the two holes. This means that the crack will generate on the wall of a blast hole first and then propagate towards the neighboring holes.

A new technique, named `Microprocessor-Controlled Stroboscope High Speed Photography,' has been tested. This instrument uses sequential flashes of different colors, with the frequency controlled by a microprocessor to freeze the motion of individual moving tracer particles. By this means, a series of different color images of moving particles can be recorded on each frame of film. Accordingly, the velocities, accelerations, and trajectories of moving particles can be determined, and circulation patterns can be traced. Tests were carried out with particles of 100 to 500 micrometers diameter in a circulating fluidized bed (CFB), with measured velocities from 0.56 m/s to 10 m/s to demonstrate the usefulness of the new technique.

In this paper the procedure for experimental measuring of the radial distribution of a ball sample material density under explosive spherical compression is presented. Sample materials are Fe and Pb. The technique was developed for measurements conducted under material dynamic compaction. Measuring was done by a pulsed radiography method. Object simplest open x-raying was applied without the use of collimating elements or equalizer filters.

The formation of latent radiation image was investigated using the method of statistic simulation of process of gamma radiation interaction with a gas discharge converter. The process of gamma quanta interaction with an input electrode was simulated, then we observed the paths of electrons coming out into gas and radial distribution of energy losses in gas. This permitted us to determine the dependence of registration efficiency, intrinsic unsharpness, and dose sensitivity on Bremsstrahlung boundary energy 10 - 100 MeV. Experiments gave dose and frequency-contrast characteristics of the gas discharge converter which have good agreement with calculation results. Intrinsic unsharpness of the gas discharge converter in the said energy range equals 6.4 to 3.4 mm, and dose sensitivity was from 2.7 X 10^-8 up to 2.0 X 10^-8 C/Kg.

A Q switched Nd-YAG laser has been used to generate ultrasonic waves at air-solid boundaries. The high energy and power density at the laser focus leads to the formation of a plasma on the surface of the solid. The solid surface is heated to the vaporization point and the combined effects of the laser plasma and surface ablation lead to shock waves in the air and a high pressure transient acoustic wave in the solid. This laser generated ultrasound is being used to study material properties and is used in non-destructive testing. Laser ultrasound has been studied using a range of transducers to confirm the thermoelastic and ablation regimes. But in general these techniques do not give the spatial as well as temporal behavior of the waves. Schlieren photography using a dye laser has been used to study the propagation of the various wave types at an air-solid boundary and Mach Zehnder interferometry has been used to determine the absolute pressure in transparent solids. The pressure has been measured as a function of time and the radial dependence is in excellent agreement with the direct pressure transducer measurements of other workers in the ablation regime.

With a bright front illumination of the shaped charge jet it is possible to observe its surface. This technique allows us to check and reassess the jet surface smoothness and provides new insight into the field of the desired material properties, leading to longer particulation times and therefore less disturbed jet particles.

Coplanar slow-wave electrode structures capable of matching the velocities of microwaves to those of optical waves in compound semiconductor based electro-optic modulators are described. In such an electrode microwaves are slowed by periodically adding pairs of capacitive loading fins to the electrode to increase its capacitance per unit length, without obtaining a corresponding decrease in its inductance per unit length. Electro-optic modulators having wide bandwidths and requiring small amounts of modulating power may be realized by using slow-wave electrodes to achieve the velocity-match condition. The theory of operation of, and the results of some measurements on, electrodes of this type are presented.

It is important to visualize the intricate bubble behavior and the strong agitation of liquid near the heating surface to clarify the details concerning boiling mechanism. The visualization of nucleate pool boiling phenomena was confirmed by means of shadowgraphy using a still- camera (Nikon Photomic Camera) with the speed of 2000 frames per second. Illumination was provided by a photo spotlight or a stroboscope. The photographs show that the boiling phenomena and bubbles' behavior are varied for the heat flux of nucleate pool boiling based on the experiments. By considering the effect of revolving angle and the influence of a space between a tube and a tube, experiments have been carried out to investigate the nucleate pool boiling phenomena on horizontal stainless-steel-multi-tube in saturated distilled water. These experiments were performed for atmospheric pressure, for a stainless-tube diameter of 1.0 mm for a length of 80 mm, for a region of natural convection to nucleate boiling near burnout. From these results, photographs show that the successive motion and shape of bubbles during their process of detachment on the heating tube surface varied with increasing heat flux.

Investigation of shock-wave processes requires multichannel means to measure time intervals. By using measured intervals, velocity and shape of the front surface of shock and detonation waves, and that of moving bodies, are determined. In this paper one of these optical fiber systems is presented. Polymeric light guides, served also for retransmission of optical signals, are used as gauges. The essence of the described system is that the point image of the surface of any form in it, which is arbitrarily oriented in space, is converted into a flat (linear) one, recorded with a chronograph. The results of the system information potential investigation, including a number of recorded signals, time resolution, and measurement errors, as well as sensitivity of the method depending on signal parameters, photochronograph and photographic films characteristics, and the results of an experiment, are presented. The developed system enables us to register up to 6000 channels in the same experiment, time resolution of which does not exceed 20 ns.

A new high speed recording procedure of holographic information is proposed, named `streak holography.' This kind of record is useful particularly for velocity and acceleration measurement, and for the observation of a moving object whose trajectory cannot be predicted in advance. A very high speed camera system has been designed and constructed for streak holography. A ring-shaped 100-mm-diam film is cut out from the high-resolution sheet film, mounted on a thin duralmin disk, which has been driven to rotate directly by an air-turbine spindle. The feasibility of the camera system has been examined by the experiments of relatively slow phenomena, like free fall of small glass spheres and the motion of them to the direction of the optical axis.

Gated image intensifier tubes (IITs) with microchannel-plate (MCP) may be used for the diagnostics of very fast transient phenomena such as predischarge development in gases. The gating pulse is usually applied to the cathode of the IIT while the voltages across the MCP and the anode remain constant. Due to the transparency of the cathode, which is in the range of 10^-5, and the low emission energy of the MCP-material, which can be below 2 eV, a small portion of radiation is able to pass the cathode during its non-gated state and release electrons directly from the MCP-material. These electrons are amplified by the MCP which may result in an aliased picture. Therefore the amount of radiation which can be applied to the IIT during its non-gated state is limited. In order to increase the gating efficiency of the IIT combined gating of the cathode and the MCP is used. This allows us to take pictures from predischarge phenomena with very low luminosity followed by the intensive radiation of the high current arc. Similar problems exist during investigations of the recovery phase of high current switches. In addition gating of the MCP reduces all kinds of noise caused by the MCP during the relatively long integration time of the video-camera usually connected to the IIT. A single frame high speed camera with gated photocathode, gated MCP, and variable exposure times between 700 ps and 5 ns has been developed. The transparency could be decreased from 1E - 5 of less than 1E - 13.

The fundamental studies for producing plasma flash x rays using three types of generators are described. The flash x-ray generators used in this experiment are as follows: (a) solid-anode radiation tubes in conjunction with a large-capacity condenser of 199 nF, (b) liquid-anode radiation tubes utilizing a combined ceramic condenser of 10.7 nF, and (c) a flash vacuum ultraviolet (VUV) tube having a surface-discharge-glass substrate driven by a polarity- inversion-type transmission line with a condenser capacity of 14.3 nF. The radiation tubes were of the demountable types and were connected to vacuum pumps with pressures of about 1 X 10^-3 Pa. Using type (a) and (b) generators, each condenser was charged from 40 to 60 kV by a power supply, and the electric charges in the condenser were discharged to the radiation tube after the triggering. In contrast, when a type (c) generator was employed, the condenser was charged from -20) to -30) kV, and the maximum output voltages of about -1) times the charged voltages were produced after closing a gap switch. Using these generators, the plasma flash x rays were easily generated, and high-intensity soft x rays of about 10 keV were obtained by using a solid-anode radiation tube. In particular, although the K(alpha) satellites were produced when a type (a) generator with a copper anode is employed, the intensities of the spectrum lines including satellites of copper K(alpha) were considered to be amplified by using a double anode (tungsten mounted copper anode).

This paper describes the features of the copper vapor laser developed in IHI Research Center for measurement of high-speed fluid, and the preliminary results of observed measurement on actual fluid flow in a shock tube. The copper vapor laser we have developed selects two different wavelengths (green or yellow) and couples them with an optical fiber. Further, in correspondence with external triggering from a shock tube or other devices, it is possible to freely set the timing for generation of laser pulses. Applying the copper vapor laser for the schlieren light source, we were able to visualize the formation of shock waveforms around an airfoil placed in a shock tube.

A novel form of reflector, incorporating an array of microlenses, is described. Incident illumination is reflected through an angle of deviation that is nominally independent of the angle of incidence. The reflector performs a function that is similar to a retroreflector, but differs in that the angle of deviation is other than 180 degree(s). This dispenses with the need to use a beamsplitter to extract the reflected wavefront. The consequent reduction in light loss is of benefit to high speed and other forms of photography.

Holographic interferometric flow visualization was successfully applied to underwater shock wave focusing and its application to extracorporeal shock wave lithotripsy (ESWL). Real time diffuse holograms revealed the shock wave focusing process in an ellipsoidal reflector made from PMMA and double exposure holographic interferometry also clarified quantitatively the shock focusing process. Disintegration of urinary tract stones and gallbladder stones was observed by high speed photogrammetry. Tissue damage associated with the ESWL treatment is discussed in some detail.

The characteristics, including temporal resolution, dynamic range, and time distortion, of our femtosecond streak image tube developed a few years ago have been examined systematically by experiments under different conditions. It can be concluded from the experiments: (1) in order to achieve a temporal resolution of less than 400 fs with acceptable fluctuation the travelling wave deflection system and specially processed photocathode have played an important role, (2) to expand the dynamic range and to stabilize the temporal resolution it is of importance to minimize the noise and to accumulate the signal along the slit, (3) to accomplish above signal accumulation along the slit the time distortion has to be eliminated, which could be realized by using our specially designed optical lens. The aim of this study is to improve the temporal resolution up to 50 - 100 fs by a newly designed femtosecond streak image tube.

A new electric circuit for generating extremely fast triangle waveform pulse with avalanche transistors has been designed and developed. In order to reduce the jitter of this circuit, a specially designed trigger unit has been employed. The experiments have shown that the full width at half maximum (FWHM) of the generated triangle waveform pulse is 3.5 ns and its rising and falling times are both 2 ns at the amplitude of +/- 1.3 KV. The testing has also indicated that its delay time and jitter are 8 ns and +/- 15 ps, respectively when the light signal changes by 30%. This circuit will find wide application in the picosecond framing and femtosecond streak cameras.

The experimental measurements of soft x-ray laser spectra with high time-resolution (approximately 50 ps) are reported. The Ge-slab targets were irradiated by line focused laser beam with irradiance of 1.2 X 10¹³ w/cm². The laser pulse width is 1 ns. Using a flat field grating spectrometer and a soft x-ray streak camera, we have obtained temporal characters of four soft x-ray lasing lines with wavelengths of 19.6, 23.2, 23.6, and 28.6 nm emitted from the 3p - 3s transitions in Ne-like Ge plasma. The results indicate that these lines did not appear at the same time and their duration was about 0.83 ns.

An optical technique is carried out in our lab which uses velocity interferometers to measure the shear-wave velocity on the surface of a sample. By the planar impact on a one stage gas gun with 57 mm diameter and the anisotropy of Y-cut quartz, a combining pressure-shear loading in Ly-12 Al bonded to the rear surface of Y-cut quartz is generated. Two velocity interferometers were employed to measure simultaneously the longitudinal and transverse velocity histories on the free surface. An optical alignment method which uses laser to adjust the parallelism of the impactor and the target is also described and a measure to overcome the low laser power used in our experiments is also put forward in this paper.

Interrelation between current sensitivity at (lambda) >= 1.06 micrometers and thermoemission current (calculate data and their correlation with experimental results) is used as an indicator of choice between the donor and acceptor models of Ag-O-Cs-photocathode.

The report reviews and discusses a tendency of development of picosecond x-ray streak cameras (XRSC) designed in the All-Russian Research Institute for Optical and Physical Measurements (VNIIOFI). The main feature of an XRSC is its cathode grid unit. The set of XRSC developed in the VNIIOFI differ principally in the design of this unit.

High-speed photography is useful in increasing accuracy, reliability, and efficiency of experimental research when studying dynamics of fast mechanisms and machines, new highly productive processes, and when solving aerodynamic and hydrodynamics problems. Now the Industrial Association `Krasnogorsky Zavod' has developed and produces on a commercial basis a new high-speed drum camera SK-2 with a mirror compensator. The camera uses optical compensation of the image shift relative to the film, which is fastened to a rotatable drum, and may operate in framing, streak, and flash light modes.

One of the most important car checking problems consists in safety testing which includes trials for different types of collision, e.g., frontal and lateral. This allows us to study deformations of the automobile and its parts during the impact. To obtain reliable data on overloading, acceleration, deformation, force load on the car's body as well as on the anthropomorphic dummies inside it, use is made of rather a great number of different techniques. Highly informative among them is high-speed cine recording which allows us to register variations that occur during a fraction of a second, and then to reproduce with variable rate the frame images obtained. This makes it possible to study the impact parameters variations much more accurately.

An improved control unit for the high-speed photorecording camera VFU-1 is explained. Compared with the original control desk it provides a wider range of the recording camera mirror rotation frequencies of 600 - 80,000 revs/min with better stability of +/- 10% at the minimal rotation frequency. The basic unit provides 3000 - 75,000 revs/min with stability +/- 20% at the minimal rotation frequency. Other features include smooth control of the rotation frequency and two subranges of rotation frequencies. The improvement in stability is achieved by using a dc voltage stabilizer of the camera electro-motor feed at low rotation frequencies. The features of the motor are taken into account. The shortcomings of the basic control unit are corrected, which makes it more convenient in operation. The application of the unit extends the range of scanning velocities up to 4.8 - 640 m/s, and so extends the potentialities inherent in VFU-1.

The high-speed camera `Galdiolus-1' is a high-precision recording device and is widely used for investigations in hydromechanics systems, as well as in other fields of technical mechanics.

Automatic processing for pulses with duration lying in microsecond and nanosecond ranges takes a rising interest. However, the available digital electronics facilities are not able due of their low speed to convert and store these signals directly with required resolution for a detail analysis of pulse response shape and other parameters. Therefore, researchers are forced to use another facilities, for instance, a storage oscilloscope. An oscilloscope as the most widely used apparatus in researching of unsteady processes gives good results, when a manual mode of operation is used. However, it is not adapted to obtaining both the express information and the information that requires a quantitative analysis. Also, it is impossible to provide the acquired data with fast processing, that is necessary for industrial products testing. Often oscilloscope images have low brightness and low contrast. To overcome these problems we have to create hardware and software for the microsecond-range oscilloscope image processing. The structure of hardware for image collection (Picture Transformer - PT) is given in Fig.1. PT consists of four units: an image converter (IC); a TV camera; a TV-camera controller, which makes the time discretization and digitization of a videosignal and the image framing according to the video synchronizing signals; an image memory for image storing in frame size. The main operational characteristics are: image frame size - 512x512 pixels; resolution in brightness-64 gray levels; time of the frame storing into the image memory - 40 ms; speed of the interchange with computer - maximum 2.5 Mb/s; power consumption - 80 VA; physical dimensions 470x310x60 mm3 added by TV camera and IC.

A simple technique based on an injection laser diode with electrical subcarrier modulation and the fiber Michelson interferometer usage for dynamic characteristics measuring of different optical and optoelectronic devices is described. The concept avoids the requirement for single mode components and does not suffer from many problems inherent to a traditional interferometric system. Experimental results have shown a time resolution of 0.2 ps with a dynamic range of more than 30 dB. The applicability of the technique for fiber optics sensing and diagnostics of fiber optics devices is demonstrated.

A new type of integral-optics bistable element, based on electroabsorption waveguide distributed feedback structure, is proposed and investigated. A model of the device is formulated to calculate its main electrical and optical characteristics. The element has high on/off ratio (more than 10) in a bistable regime, the switching power is less than 5 - 6 mW, while the switching time is limited only by the RC-constant of the electrical circuit and is less than 10 ps.

The turn-on moment of a laser simulated emission generation is the subject of random fluctuations called jitter due to the statistical nature of the nonequilibrium carrier accumulation process in the laser active zone. The experimental research into the jitter in DFB and Fabry- Perot lasers shows its strong dependence on an operational mode of the laser. It was determined that the statistical distribution of the time fluctuations of light pulse front and back sides may differ in a laser biased below threshold and operating at a high modulation rate when the so-called pattern-effect is being displayed. The statistics of the jitter of the pulses rear fronts remains Gaussian, but as the modulation frequency grows it becomes more sophisticated for the head fronts.

Investigations of fast processes in transparent media are being successfully performed by means of coherent optics methods such as interference, correlation, laser Doppler anemometry (LDA), etc. All these methods require splitting and further bringing together laser beams and following the processing of a useful signal. It is very difficult to fulfill these requirements with the help of traditional optical means, especially for many beams with complex wave fronts. In these cases one has to use optical schemes with a great number of elements, which results in great losses at reflection, in depolarization of the beams, in worsening of the device vibration stability, and in climatic changes. It is possible to get rid of all these disadvantages by using holographic optical elements in such devices.

Rapid atomic analysis of an impurity concentration in various substances becomes more necessary nowadays for successful realization of different technological processes. Environmental control put similar requirements to a diagnostic apparatus. Moreover, the analysis is to be done in many cases with a very tiny sample volume of about 10^-12 - 10^-18 m³. All the above-mentioned requirements are met by the proposed laser spark element analyzer, in which the substance is ionized and excited by an optical pulse. The element and quantitative analysis is made with emission spectra which depend greatly on the sample chemical composition.

Studies on high-speed phenomena, occurring in a closed liquid-filled tank as a result of its perforation, is of great interest from both a theoretical and practical point of view. Processes of that kind are usually being registered by x-ray recording and high-speed filming. The photos obtained make it possible to analyze the dynamics of the cavity and the shock wave propagation in the liquid. The authors have developed an experimental installation for the purpose of registering the phenomena caused by perforation of liquid-filled tanks. A high- speed camera acts as a command unit of the installation. The camera is started from a remote desk and when the rotating mirror achieves the desired rotation velocity, the camera signals the gun to fire. The projectile's velocity is measured by an induction velocity meter, and the information obtained enters a synchronization unit, which works out signals for switching on the flash lamp and x-ray apparatuses, as well as for memory oscillograph sweeping. X-ray recording and high-speed registration are accomplished in orthogonal planes. Front and back walls of the tank are steel targets, and side walls are made of transparent material. The movement of the projectile and the cavity dynamics in the liquid are registered by the camera in transmitted light (the camera is placed against a diffusing square -- marked reference screen).

Stack gas cleaning from dust highly dispersed particles in cracking of oil distillates or in production of synthetic rubber, as well as in some other petrochemical or petroleum refining processes, takes place in an electrostatic precipitator -- an apparatus of electronic and ionic technology. Intensification of the process results in increasing waste gas volumes as well as increasing gas velocities in the active section of the electrostatic precipitator, degradation of separation efficiency, and ecological problems.

For investigation of a pipe welding process at high-frequency heating aimed at increasing of pipe quality and decreasing of spoilage, the use of high-speed recording and TV-technique is considered to be effective. The authors have created a visual inspection system for pipe welding process studies at a tube mill of the Novomoskovsk Pipe Plant.