This PDF file contains the editorial “Editorial” for OE Vol. 40 Issue 08

We present a novel method for fabricating microlens mold arrays. The mold array is fabricated using focused-ion-beam milling (FIBM) on a substrate of bulk SI. The 2-D profiles and surface roughnesses of the fabricated molds are measured using a laser interferometer. Finally, the mold array is used for hot embossed molding. The surface roughnesses of the mold and the replica are 2.5 and 8 nm, respectively. We define surface roughness as the arithmetic mean of the absolute departure of the roughness profile from the mean line. A profile of the replica is acceptable for practical use. The measured size of the replica corresponds well with that of designed array.

For simple homogeneous canopies, we predict canopy thermal infrared hot spot variations of 2°C at the surface with respect to nadir viewing. Dependence on leaf size is weak as long as the ratio of leaf size to canopy height is maintained. However, the angular width of the hot spot increases as the ratio of leaf diameter to canopy height increases. Atmospheric effects minimize but do not eliminate the TIR hot spot at satellite altitudes.

The fractional Fourier transform (FRT) is used in the analysis of surface motion in combination with the speckle photography technique. It is demonstrated experimentally that the extra degree of freedom made available by the use of an optical implementation of the FRT allows controlled variation of both the minimum resolution and dynamical range of measurement of tilting (rotational) motion.

We present a quantitative analysis of several local activity indicator properties and provide comparisons between them. We illustrate that the considered local activity indicators can be applied as adaptation parameters to locally adaptive hard-switching processing (filtering) of images. The cases where images are corrupted with additive or multiplicative noise having different probability density functions and, possibly, spikes are considered. The advantages of the designed adaptive hard-switching filtering algorithms are discussed and demonstrated for simulated data. Recommendations concerning the selection of local activity indicators and threshold values are given.

Direct fabrication of continuous surface-relief gratings on acrylics using a high-precision diamond-cutting process is reported. Critical conditions such as the diamond-tip radius and cutting step were selected by taking account of a designed grating profile and an expected roughness on the obtained grating surface. Experimental results for a 13-fanout continuous phase grating are presented. The phase profile was optimized using a stochastic design algorithm. A 3-mm-thick acrylic plate was carved into a grating that provided a measured efficiency of 85% with Fresnel reflection losses uncorrected. The diffracted intensity distribution was rather sensitive to any departure from the designed profile, the 0th-order intensity being particularly affected. Compensating the material's springback was found critical to the grating's performance.

The condition of energy conservation in a two-beam grating interference element imposes a phase shift of m? on the diffraction order m of one of the two incident beams relative to the same order of the other beam. The expressions of the resulting interference products are given and their implications for a diffractive interferometric displacement sensor are discussed.

The optical property of a solid immersion lens with a flat surface, coated with an opaque thin film with a rectangular hole is investigated on the basis of a three-dimensional vector mathematical model. The laser beam is focused on the center of the hole. It is shown that the side lobe in the energy flux vector distribution in the focal plane of a solid immersion lens with a large numerical aperture (>1.5) significantly decreased the optical efficiency of the lens. The results of digital simulation show that an opaque thin film with a hole, equal or larger than the width of the main lobe, significantly increases the transmission coefficient because it closes the inverse electromagnetic energy flux in the side lobe. The hole has an unimportant influence on the energy flux vector distribution in the main light spot when its dimensions are equal or larger than the dimension of the central lobe of the laser beam. The distribution of electrical and magnetic intensity is also investigated.

Yarn density, or yarn count, in a woven fabric is an important parameter that influences fabric structure and properties. The measurement of yarn density often involves tedious, inaccurate procedures. This paper presents a new method developed for rapid and accurate measurement of yarn density. The method takes advantage of the structural features of a woven fabric, and uses a computer-generated grating (a reference pattern) to produce digital moire interference on the fabric. The moire image is then demodulated and processed with a phase-shifting technique so that moire fringes can be extracted and counted. From the relation between the pitches of the grating and the moire fringes, the yarn density can be calculated. This technique does not need complicated optical setting or an interferometer to form moire fringes with fabrics, permitting fast and accurate measurement of yarn densities.

Degenerate four-wave mixing measurements were employed to obtain first-order diffraction efficiencies of dye-doped and polymer- dye-doped liquid crystals. A sixfold enhancement in the diffraction efficiency (12%) was found for the liquid crystal doped with 1% azo dye and 1% polymer, compared to a 2% diffraction efficiency found for the liquid crystal containing 1% azo dye. Polarization dependence of absorption and diffraction studies, coupled with the absence of two-beam coupling, support a grating formation based on photoisomerization of azo dye molecules, which leads to a reorientation of the liquid crystal phase.

EOPACE (electro-optical propagation assessment in coastal environments) was a 5-yr multinational and interdisciplinary effort to improve the performance assessment for electro-optical (EO) systems operating in coastal environments. The initial results of the EOPACE program include: (1) the parameterization of the surf-zone generated aerosol-size distribution as a function of swell height; (2) the characterization of aerosol plume structures and the transport of surf generated aerosols; (3) the development of a quantitative surf aerosol source function; (4) the description of the contribution and impact of surf-zone generated aerosols on coastal infrared (IR) transmission; (5) the measurement and modeling of the near surface transmission effects (aerosol and molecular extinction, refraction, scintillation, and wave shadowing); (6) an analysis of the contribution of anthropogenic and land derived aerosols to the air mass characteristics in the coastal zone; (7) the application of direct and remote sensing techniques to develop the scaling parameters for aerosols in the prevailing air mass; (8) an analysis of near ocean surface bulk meteorological scaling which works well for unstable conditions but is less reliable for neutral and stable conditions; and (9) the incorporation of the improved sea radiance models into TAWS (target acquisition weather software) which improved the error analysis by a factor of 3. These initial accomplishments are described in this overview of the EOPACE effort.

Electro-optic intensity modulators at ? = 1.55 ?m are produced in LiNbO3 substrates using strain-induced channel waveguides formed by magnetron deposition of a surface metal film and lift-off technology. The static strain resulting from thermal expansion mismatch between the substrate and the metal film that is caused by the plasma temperature during deposition induces a localized increase in the refractive index via the strain-optic effect. Modulation depth of 100% at a ?-rad voltage of 16.1 V is demonstrated. Electro-optic modulation behaviors in channel waveguides fabricated using strain inducing surface metal film are compared to ones formed by thick SiO2 surface film.

The tolerance to data loss of a double random phase encoding encryption system is studied, and the signal-to-noise ratio (SNR) of the decrypted image is investigated when part of the encrypted image is lost. In electronic implementation, the SNR will be enhanced by reducing the ratio of the sampling number of the image to the total sampling number. In optical implementation, the SNR can be increased by using a phase mask with higher spatial frequency. Both the theory and computer simulations are demonstrated.

The first example of hybrid diffractive/graded-index optical integration is presented. The demonstrated 1:3 beamsplitter for fiber optics consists of two GRIN lenses and one diffractive element, which are fabricated by ion exchange and stacked together to form a solid unit. The unit is coupled with the input optical fiber and with three output ones.

We report the acousto-optic induced multiband reflection in sinc-sampled fiber gratings, in which the induced-wavelength-channels at both sides of each existing channel can be switched by applying an acoustic wave propagating along the fiber. This novel comb filter can redirect a large number of wavelength channels at the same time in a wavelength division multiplexing (WDM) system and will offer a new functionality in the evolution of the current WDM network toward a more complex future system with automated routing functions.

The design and modeling of strongly pumped, doped silver halide fiber amplifiers are presented. Lasing properties of doped silver halides, in the near or mid-IR region, are studied experimentally and analyzed, based on a rate equation formalism. The analysis is applicable for both three- and four-level systems, such as Er3+, Pr3+, and Nd3+. optimal amplifier designs are suggested to obtain significant amplification.

A novel retroreflective polarization insensitive 2x2 fiber optic switch (FOS) using programmable quarter waveplates (QWPs) is introduced. Key features include low polarization sensitivity and a selfaligning module via a compact retroreflective structure. A proof of concept 2 x 2 FOS using ferroelectric liquid crystal (FLC)-based programmable QWPs is demonstrated, providing a response speed of 394 ?s and a low 10.14-mW total electrical power consumption for the worst case. Multiwavelength switch operation in the 1550-nm wavelength region indicates an average optical loss of 6.02 dB with a ±0.18-dB loss fluctuation, and an optical coherent crosstalk of -21.6 dB with a ±0.84 dB variation over a 60-nm bandwidth. The temperature dependence of our switch is investigated over a 17°C range, indicating an average 5.80-dB optical loss with a ±0.13-dB fluctuation, and an average optical coherent crosstalk of -20.5 dB with a fluctuation of ±0.42 dB. An average polarization dependent loss of 0.4 dB is also measured. A time-multiplexed FLC device addressing technique is introduced for FOS to achieve long duration operation.

We propose a method for subband coded image quality supervision using a closed loop fuzzy controller for adjusting the quantization steps. As a measure of the image quality used in the control loop, we first use the standard quadratic quality measure SNR in decibels. We then expand this measure using the compression ratio in a novel quality measure that is designed on the basis of subjective experiments and implemented with fuzzy logic. Our results demonstrate the superior performance of the proposed fuzzy quality measure over the standard SNR quality measure in terms of correlation with the subjective impression of compressed images. The proposed method should prove to be useful, especially for natural images that have decaying power spectral density.

A hyperspectral imaging system has been developed to image the laser-induced fluorescence of objects on the ocean floor to discriminate between man-made and natural materials. The information captured with this sensor allows one to examine the reflectance of the ocean floor, Raman scattering from water molecules, and laser-induced fluorescence from suspended chlorophyll and yellow matter in the ocean water and from objects on the ocean floor. The excitation laser is a Q-switched, diode-pumped, frequency-doubled Nd:YAG laser. The receiver is a time-gated image intensified CCD camera with wide field-of- view optics designed for high radiometric throughput. A grating prism or GRISM placed before the receiver is used to spectrally disperse the returned light. The complete system forms a hyperspectral image of the laser-illuminated ocean floor.

We develop a model for the probability density function (pdf) of the irradiance fluctuations of an optical wave propagating through a turbulent medium. The model is a two-parameter distribution that is based on a doubly stochastic theory of scintillation that assumes that small-scale irradiance fluctuations are modulated by large-scale irradi- ance fluctuations of the propagating wave, both governed by independent gamma distributions. The resulting irradiance pdf takes the form of a generalized Kdistribution that we term the gamma-gamma distribution. The two parameters of the gamma-gamma pdf are determined using a recently published theory of scintillation, using only values of the refractive-index structure parameter Cn2 (or Rytov variance) and inner scale l0 provided with the simulation data. This enables us to directly calculate various log-irradiance moments that are necessary in the scaled plots. We make a number of comparisons with published plane wave and spherical wave simulation data over a wide range of turbulence conditions (weak to strong) that includes inner scale effects. The gamma-gamma pdf is found to generally provide a good fit to the simulation data in nearly all cases tested.

Generally, an acousto-optic modulator (AOM) is used for frequency splitting in an interferometer. In this paper we introduce a new utilization of the AOM. In our newly developed self-compensation heterodyne vibrometry the AOM is used as the vibration-detecting sensor. The AOM crystal is firmly attached to the target of measurement. The frequency of the first-order beam is modulated by the vibration of the object. Hence by measuring the frequency shift in the first-order beam of the AOM the vibration characteristics of the target can be deduced. The main advantage of this system is its error compensation ability. Experiments carried out successfully demonstrated the capability of the newly designed system for error cancellation when it suffers a large vibratory perturbation. The main limitation of the new metrology is its destructive nature, which restricts its potential applications.

The major limiting factor in scaling solid state laser average power is thermal heating. A simple and effective solution, which is used to obtain pump and temperature distributions in the laser rod using an approximate formula to calculate the absorption of the pump ray in the rod, is provided. The calculated data fit well with the experimental data, which are obtained from an IR camera. This analysis can provide valuable data for efficient coupling of pump source and subsequent correction of the thermal distortion inside the laser resonator. Most important, one can clearly observe temperature distribution in the rod and temperature difference between the center and edge of the rod with an IR camera, which benefits adjustment of the pump diodes.

We report mode-locked laser operation of a diode-pumped Nd:Lu:YLiF4 crystal. This new laser material allowed generation of pulses shorter than those obtained from the well-established laser medium Nd:YLiF4 in the same experimental configuration. The modelocking regime was obtained by introducing a very weak acousto-optical modulation with Kerr-lens-induced pulse shaping. A suitable negative value of the intracavity group-velocity dispersion was introduced to enhance the initiation and stabilization of the regime. Pulses as short as 4.5 ps were readily obtained, without troublesome optimization procedures. To allow comparison with previously reported results for Nd:YLiF4 systems, we review the importance of spatial hole-burning effects in modelocking operation.

Treatments utilizing different chemical compositions are employed to preserve the surface of historical stone building. The uniform distribution of the protective treatment and the conservation of its integrity over the years are crucial factors for an efficient protection of monuments. A technique that enables a remote mapping of the treatment and its characteristics is therefore very attractive. We describe the first experiments devoted to the investigation of the potential of fluorescence lidar in monitoring protective treatments on stone surfaces. Dolomitic marble samples are treated with different protective substances, and are then analyzed by a laboratory setup that simulates a lidar measurement. Although further investigations will be necessary, these laboratory results indicate an interesting potential for lidar in the nondestructive, remote monitoring of protective treatments.

An improved optical security system based on correlation between two phase-only computer generated masks is proposed. The two phase masks are placed together at the input plane of a joint transform correlator. A priori known output image is obtained in the system output only if one mask is the right key for the other mask. In addition to a simple verification, our security system is capable of identifying the type of an input mask according to the corresponding output image that it generates. The two phase masks are designed using an iterative optimization algorithm with constraints in the input and output domains. Computer simulations are presented with the resultant images formed by the two phase-only elements.

A strategy for designing optical systems that are optimized for multiple optical functions on the basis of wave optics is presented. Each optical function is composed of an input field, a set of fixed system parameters, and a merit function. A design algorithm is proposed that is applicable for optical systems consisting of a transmission operator followed by an arbitrary linear operator. The goal is to find the transmission operator, which is optimal for all optical functions simultaneously. In later design steps, this transmission operator can be transformed to real optical elements, for instance, by using the thin element approximation. It is shown that the algorithm is efficiently applicable by investigating two sample applications for multifunctional wave optical design: the design of tolerant systems and 3-D beam shaping.

To create a hybrid system applied to mechanical structure analysis link to experimental optical techniques (EOTs) and computer modeling (CM), the correlation problem between Cm and EOT methods must be solved. A mapping correlation algorithm (MCA) is proposed as the interface between both techniques. Out-of-plane electronic speckle pattern interferometry (ESPI) as the experimental optical technique and a commercial finite element method (fEm) package are employed. The MCA proposed is based on a set of mapping functions, which are found by least-squares algorithms and enable the compensation of image distortions produced by the experimental optical setup. The algorithm was tested initially on a simple 2-D structure and two 3-D complex mechanical structures. Results are reported. Further, the MCA algorithm linking ESPI-FEM methods is applied to out-of-plane displacements over a rectangular plate under stress. Numerical and experimental results along with their error analysis are also presented.

We describe a stereoscopic measurement method to study the coplanarity of solder balls on a ball grid array (BGA) packaging. The optical system consists of two long-focal-length lenses and a two- channel digital image grabber. The proposed technique uses image recognition and digital correlation, which simplify the calculation procedure. The computation requires only a few seconds to calculate the height of a few hundred balls. The technique is suitable for in situ measurement in BGA manufacturing.

Experimental solid mechanics relies heavily on surface displacement and deformation gradient measurements. Digital image/ speckle correlation (DISC) uses digital image processing to resolve displacement and deformation gradient fields. The practical implementation of DISC involves important challenges such as computation complexity and the discrepancy of the sensitivities and accuracies claimed in previous studies. We develop an iterative, spatial-gradient based algorithm, which uses only first-order spatial derivatives of the images before and after deformation. Simulated images are then used to verify this algorithm, as well as to study the impact of speckle size on the accuracy. Based on these simulations, the sensitivity of DISC to displacement and deformation gradient, as well as an optimal speckle size for optimal accuracy, is recommended. The algorithm is then calibrated using rigid body translation and rotation, and an application of DISC to thermomechanical diagnostics of electronic packaging is also presented.

Methods for partial response maximum-likelihood (PRML) detection and crosstalk cancellation are discussed. In accordance with the demand for increased recording density, a 20 Gbyte digital versatile disk (DVD) ROM channel is considered. The channel is modeled to be close to a real optical channel using DIFFRACTtm. After comparing the spectral characteristics of various PR polynomials, P(D) = 1 + D +D2 +D3 is proposed as a target PR. The performance of the system is illustrated under the condition that the readout signal is degraded by crosstalk, radial tilt, and nonlinear distortions in optics. Finally, we present the multispot detection technique for crosstalk cancellation. The simulation results show that if no radial tilt is present, crosstalk is fully cancelled.

A new two-load-step approach to the phase-shifting method is presented for the full field determination of both isoclinic and isochromatic parameters in photoelasticity. The ambiguity that exists in the phase-shifting photoelasticity is overcome by investigating the relationships between the phase retardation introduced by two different load steps. The isoclinic angle is automatically determined in the correct range [-?/2, ?/2] and the isochromatic parameter is therefore obtained unambiguously. The results obtained from a bending test and an irregular specimen subjected to multiple forces demonstrate the effectiveness of this method. Compared with the load-stepped method (Ekman and Nurse, 1998) or the three-load method (Asundi et al., 2000), this new algorithm is a simpler approach and is easier to execute.

A commonly used measure of illuminance is a diffuser that is used as the element for the cosine correction of its photometric head. Since the diffusing element is, to some extent, spectrally selective, the spectral coefficient of transmission depends on the luminous flux angle of incidence on the diffuser. The selective characteristic of the transmittance of the diffusing element affects the quality of the spectral correction. Even when both the selective spectral characteristic of the diffusing element and the spectral and cosine characteristics of the diffuser are taken into account in the design of the illuminance meter photometric head, it still contains spectral correction errors. These inherent errors are due to the diffuser.

For the first time, by using Aquapol-5 and Aquapol-7, polishing tools' present-day measuring means, and a new technology of precision polishing of glass optics, the surface finish of Ra< 1 nm and the reflected light scattering factor of Kv ? s0.003% have been achieved.

An interference profilometer for measuring the microprofile of superfine surfaces is described. It has a stabilized He-Ne laser light source with two longitudinal modes and two coaxial interference arms. The measuring arm is focused on the sample surface to form a small spot while the reference arm forms a large spot. As a result, the reference arm provides a constant signal and only the measuring arm will be sensitive to the irregularity of the microprofile. Mechanical vibration has a very small effect on the instrument performance. Even if vibration amplitudes reach 300 nm, the measurement noise is less than 1 nm. The instrument has a vertical resolution better than 0.2 Å root mean square (rms) and smallest form error among existing coaxial profilometers. It is well suited for measuring the microstructure on photoetched surfaces.

A new method for absolute 3-D profiling, based on the fringe projection technique using a vertical scan mode, is described. With a combined measurement of the modulation and the phase it is possible to acquire the topography without any ambiguity problems by using one grating period only. Consequently, the vertical measurement range is limited only by the free working distance and the resolution is comparable to standard fringe projection techniques. We present a microscopic solution, based on a zoom stereo microscope, which enables interesting applications in an extended microscopic range, such as the measurement of microcomponents and microshapes, for example.

We present an image analysis technique for obtaining the velocity distribution from image sequences taken with a Schlieren apparatus. With this technique, the image sequence is considered as a series of 2-D functions that are transforming gradually through the period when the image sequence is taken. The fluid movement between the two consecutive images is then obtained via functional analysis that gives the local function deformation at every image position. The velocity and acceleration of the flow field are derived. In contrast to the particle image velocimetry (PIV) techniques, the presented technique is advantageous in the situation where the tracing particles are difficult to introduce or identify. The Schlieren apparatus set up for the study is a modified positive-negative grid system. Buoyant flows produced from gas fires and gas explosion ejection are used as case studies.

An all optical ultraminiaturized sensor head for displacement measurement that has a size of less than 5 mm in square has been produced. The sensor works by means of optical triangulation. To achieve the optical function, the sensor consists of a three-layer polymer waveguide patterned by deep x-ray lithography (LIGA), a light input fiber, two detection fibers, and microcylindrical lenses, which are also fabricated by deep x-ray lithography. The fibers and the cylindrical lenses are placed into the waveguide without any active alignment by using the waveguide walls as guiding and fixing structures. The ratio of the intensities detected in the two detection fibers is the measure of the distance between the object and the sensor. High resolution of about 10 ?m is achieved in the range of 2 to 3 mm between the sensor and an object with a diffusively reflecting surface.

A robust sensor is developed for on-line measurements in paper production. The sensor is designed for optimal response to lignin in paper. A diode laser operating at 630 nm is used for excitation and fluorescence light in the wavelength region 660 to 740 nm is detected. A compact photomultiplier tube is used for fast detection with a high SNR. The measuring spot is 90 ?m in diameter. All optical and electronics components are housed in a small 250x 140x90 mm3 box. Because the system can make up to 1.2 million measurements/s the distance between adjacent measuring points can be as short as about 20 ?m, even at a paper speed of 25 m/s, as is common with a modern newsprint paper machine. The recording system can store data continuously for 45 min at this sampling rate and data from three more sensors can be recorded simultaneously with the same resolution. This high-capacity sensor system can monitor the behavior of a paper machine at much higher time and space resolution than has traditionally been possible. From test runs on four different newsprint paper machines we observed the existence of small spots of high fluorescence in the paper from one machine, characteristic behavior with a significantly lower level of fluorescence in periodical sections of about 200 m in another machine, and that wire marks and periodical patterns could be very well identified from the fluorescence recordings. Such data have proven to contain important information for the papermaker concerning, for example the relative shrinkage of the paper web in the drying section of the paper machine.

A reconstruction algorithm by the cubic spline function interpolation, which is used to recover a signal from its dyadic wavelet transform extrema (instead of modulus maxima), is proposed. Numerous experiment results demonstrate its satisfying properties. Compared with previous algorithms it is simpler, more straightforward and faster.

Much research has been devoted to locating multiple targets on the condition that there is only one pattern in the reference image and more than one such pattern in the input image. We, however, propose a new correlator to locate and display multiple different targets when both the reference and the input images contain many different patterns. This correlator is based on the two-dimensional (2-D) discrete rotational Fourier transform (DRFT), which extends the one-dimensional (1-D) DRFT. Since the DRFT domain of an image contains information both in the spatial domain and in the frequency domain of the image, we use this property to locate and display the matched targets. The DRFT-based correlator first obtains x?[u1,u2]H*?[u1,u2],where x?[u1,u2] and x?[u1,u2] are the DRFTs of the input image and the reference image, respectively; then the inverse discrete Fourier transform (IDFT) of x?[u1,u2]H*?[u1,u2], yields many cone-shaped correlation peaks. A correlation peak stands for a matched pattern between the input image and the reference image. To display the shape of the matched pattern, x?[u1,u2] is shifted according to the position of the correlation peak yielding x?[u1,u2]. Finally, |x?[u1,u2]H*?[u1,u2]| displays the shape of the matched pattern. Like the conventional correlator, the DRFT-based correlator can recognize only the translated versions of the patterns in reference image. The purpose of this approach is to recognize multiple different targets simultaneously. The properties of the proposed 2-D DRFT are also presented.

Abstract. We propose a new two-color cancellation algorithm as an infrared (IR) counter-countermeasure technique for efficient target tracking under IR countermeasures, such as flares. For the proposed algorithm, we use two different spectral bands in the middle and near iR regions and define the ratio between the two bands' signal (MNR) to estimate the spectral distribution characteristics of the target and the flare. The proposed algorithm computes the MNR of the band signals, detects the MNR of the flare (MNRF) from the MNR histogram, and then cancels the flare signal from the middle band signal using the MNRF. We simulate the MNRF detection and the target signal extraction for the performance evaluation. The simulation results confirm that the proposed algorithm can cancel efficiently the effect of IR countermeasures under various conditions. Particularly, unlike conventional algorithms, the proposed algorithm can extract very well the target signal even when the target and flare signals are mixed in time domain. In addition, it is applicable to any ever-changing environment. © 2001 Society of Photo-Optical Instrumentation Engineers. [DOI: 10.1117/1.1386925]

Nanotribology of thin films in a LiNbO3/Ti/Pt/Au/Au integrated optical waveguide modulator (OWM) was studied using a depth-sensing diamond nanoindentation technique. Several nanoindentation tests have been conducted using a Berkovich tip and average measured values of hardness (H) and elastic modulus (E) are given. Thin film's mechanical properties are increasingly affected by the substrate properties as the diamond penetration depth exceeds 20% of the film thickness. In addition, we observed discontinuities in the load-displacement curves that were found to be in indirect relationship with the substrate/films practical adhesion. We also studied the practical adhesion of thin films by the scratch technique using a cube-corner diamond tip. The scratch tests consisted of three failure modes: ductile; ductile to brittle transition; and brittle, which were in correlation with the film's practical adhesion. Both nanoindentation and scratch tests proved that a use of platinum on top of titanium to blockade the diffusion of the gold film into the substrate relatively reduces the practical adhesion strength at the substrate/titanium interface.

The spatiotemporal coupling effect in ultrafast light pulses is described by the Wigner distribution function. This approach enables us to calculate: the output electric field intensity profile by defocusing lenses, grating pairs with different grating constants, lenses with different focal lengths, and combinations of these in pulse shapers. We also gain a clear understanding of the spatiotemporal properties of pulse shaping.

Many automatic target recognition (ATR) algorithms are intimately tied to the particular sensor they are designed for, and are not readily adapted to other kinds of sensors. Grenander’s pattern theory1–3 seeks a conceptual separation between the underlying representation of a scene, the sensors used to observe that scene, and the algorithm used to perform inference using the underlying representation and the sensor model.

Navy infrared search and track (IRST) systems aim at detecting long range airborne targets closing the naval unit at low altitude above the sea surface.1 The target signal is a 2-D pulse of small spatial extent and is well approximated by the sensor point spread function (PSF) further, the signal to clutter ratio (SCR) is usually very low and detection cannot be performed on a single frame. Multiple frame detection algorithms are therefore used to improve the detection probability.