Recent advances in laser technology, optical sensing, and computer processing of data, have lead to the development of advanced quantitative optical metrology techniques for high accuracy measurements of absolute shapes and deformations of objects. These techniques provide noninvasive, remote, and full field of view information about the objects of interest. The information obtained relates to changes in shape and/or size of the objects, characterizes anomalies, and provides tools to enhance fabrication processes. Factors that influence selection and applicability of an optical technique include the required sensitivity, accuracy, and precision that are necessary for a particular application. In this paper, sensitivity, accuracy, and precision characteristics in quantitative optical metrology techniques, and specifically in optoelectronic holography (OEH) based on CMOS cameras, are discussed. Sensitivity, accuracy, and precision are investigated with the aid of National Institute of Standards and Technology (NIST) traceable gauges, demonstrating the applicability of CMOS cameras in quantitative optical metrology techniques. It is shown that the advanced nature of CMOS technology can be applied to challenging engineering applications, including the study of rapidly evolving phenomena occurring in MEMS and micromechatronics.

With increasing globalization many enterprises decide to produce the components of their products at different locations all over the world. Consequently, new technologies and strategies for quality control are required. In this context the remote comparison of objects with regard to their shape or response on certain loads is getting more and more important for a variety of applications. For such a task the novel method of comparative digital holography is a suitable tool with interferometric sensitivity. With this technique the comparison in shape or deformation of two objects does not require the presence of both objects at the same place. In contrast to the well known incoherent techniques based on inverse fringe projection this new approach uses a coherent mask for the illumination of the sample object. The coherent mask is created by digital holography to enable the instant access to the complete optical information of the master object at any wanted place. The reconstruction of the mask is done by a spatial light modulator (SLM). The transmission of the digital master hologram to the place of comparison can be done via digital telecommunication networks. Contrary to other interferometric techniques this method enables the comparison of objects with different microstructure. In continuation of earlier reports our investigations are focused here on the analysis of the constraints of the setup with respect to the quality of the hologram reconstruction with a spatial light modulator. For successful measurements the selection of the appropriate reconstruction method and the adequate optical set-up is mandatory. In addition, the use of a SLM for the reconstruction requires the knowledge of its properties for the accomplishment of this method. The investigation results for the display properties such as display curvature, phase shift and the consequences for the technique will be presented. The optimization and the calibration of the set-up and its components lead to improved results in comparative digital holography with respect to the resolution. Examples of measurements before and after the optimization and calibration will be presented.

We have calibrated an LVDT using an optical and x-ray interferometer. We have calibrated optical interferometer using x-ray interferometer. The LVDT has calibrated by the optical interferometer. We made the monolithic x-ray interferometer with a double parallel spring structure for the translation of an analyzer lamella. One period of the x-ray interference fringe corresponds to the lattice parameter, 0.192 nm. The nonlinearity of optical interferometer has been calibrated by an x-ray interferometer. We have used a phase modulation optical interferometer. This calibration using the x-ray interferometer is directly traceable to primary standards. We have achieved the resolution of an x-ray interferometer and optical interferometer better than 0.01 nm. The optical phase stability of the interferometer is less than ± 150 pm. For the control of environmental temperature, we have used PID method. PID controller controlled the temperature inside chamber. Temperature drift was less than ± 3 mK (k = 2).

Increasing technological capabilities to produce active microelements (incl. microbeams, micromembranes and micromirrors) and their expanding areas of application introduce unprecedented requirements concerning their design and testing. Conventional two beam interferometry is one of the most popular testing method of microelements that have reflecting surface. Sometimes elements under test have complicated shape or shape gradients which restricts their testing by means of interferometer with flat reference mirror. In this paper we propose to use Liquid Crystal On Silicon (LCOS) spatial light modulator which serves as an adaptive reference mirror and phase shifter in Twyman-Green interferometer applied for microelements measurement. Initial tests have been performed and results confirming applicability of LCOS in active interferometer system are presented.

In the present work, the thermo-mechanical behavior, temperature versus thermal deformation with respect to time, of different coating films were studied by a non-destructive technique (NDT) known as shearography. Organic coatings, i.e., Epoxy, on metallic alloys, i.e., carbon steels, were investigated at a temperature range simulating the severe weather temperatures in Kuwait especially between the daylight and the night time temperatures. The investigation focused on determining the in-plane displacement of the coatings, which amounts to the thermal deformation and stress with respect to temperature and time. Along with the experimental data, a mathematical relationship was derived describing the thermal deformation and stress of a coating film as a function of temperature. Furthermore, results of shearography indicate that the technique is very useful NDT method not only for determining the thermo-mechanical behavior of different coatings, but also the technique can be used as a 2D-microscope for monitoring the deformation of the coatings in real-time at a microscopic scale.

Planar Doppler Velocimetry (PDV) measures the Doppler frequency shift of light scattered by particles entrained in a moving stream of air or gas. The technique uses a laser light sheet and one or more viewing directions to obtain up to three components of velocity within the sheet. Continuous wave (cw) lasers can be used to measure time-averaged velocity and pulsed lasers for instantaneous and time-averaged velocity. Optical fibres can be used to provide flexible deployment of the light sheet and can be combined with a beam scanner to generate a “top-hat” beam profile which provides more uniform illumination across the light sheet and can help improve signal to noise ratio. Coherent fibre bundle arrays can be used to provide flexible imaging of the light sheet. These bundles can be used with both cw and pulsed lasers and provide significant simplification of the optical instrumentation and by coupling to different imaging optics they enable a wide range of flow measurement applications. For example, standard SLR lenses can be used for external flow applications such as windtunnels, whilst the use of borescopes attached to the end of the fibre bundles enables internal flow measurement applications such as gas turbine compressors. This paper will introduce the technique of Planar Doppler Velocimetry (PDV), describe the technique used for Doppler frequency shift to intensity transduction and methods to obtain three components of velocity instantaneously and time-averaged from a laser light sheet. Optical fibres for laser beam delivery and coherent imaging fibre bundles for imaging of the laser light sheet will be presented and demonstrated on seeded air flows.

In the frame of cryogenic test on an off axis ellipsoid, it has been required to set-up an unambiguous method to determine and track the foci position during temperature transitions. This procedure was mandatory to avoid: (1) impact of the operator skills working on triple shift scheme to assure continuously monitoring of the ellipsoid shape during cool down. (2) correctly dissociate the impact of the thermal deformation on the mirror shape with respect to alignment errors. This paper will demonstrate the process, starting from ideal ellipsoid shape, then introducing 3D metrology data in a model, and finally presents the results in a practical situation.

A novel Micro Optical Probe Sensor (MOPS) is proposed for dynamic in-plane displacement sensing of small objects subject to high frequency and small amplitude of in-plane vibration. A thin reflection grating with high spatial frequency is attached to or made directly on the object to be sensed. When the micro optical probe sensor (MOPS), which includes diode laser source, optical probe generation system and photodetector, scans the diffraction grating, a sinusoidal output is generated. Each cycle of this sinusoidal waveform corresponds to one pitch of the diffraction grating. By analyzing these output signals, the vibration amplitude and frequency can be determined. The approach is validated by experiments using an Optical Pickup Unit (OPU) as the MOPS probe detector and a piece of CD as the grating element. Experiments use electromagnetic actuator (EMA) and piezo-electric transducer (PET) to generate different vibration amplitude and frequency. The measurement resolution of 0.4 micron and the accuracy of 0.8 micron are achieved. The experiments have also shown the capability of measured vibration frequency greater than 21 kHz and vibration amplitude smaller than 1 micron.

This paper presents tomographic microinterferometry as a tool for determination of 3D refractive index distribution in optically transparent elements. Principles of method and exemplary results are obtained in laboratory system are given. Concept of insensitive for ambient influence field tomograph dedicated for fast determination of refractive index distribution is given. Decreasing of acquisition and computing time is achieved by reduction of number of views, for which measurements are taken. The influence of decreasing number of projection is analyzed in order to determine a certain compromise between the quality of n(x,y,z) reconstruction and time of measurement.

We compare two modes of measurement of shallow objects using a scanning interference microscope. In one mode the object is moved with respect to the Mirau interference objective while a camera records the interference pattern. In another mode the beam splitter is moved during the scan while the object remains in focus. We use both narrowband and broadband extended LED sources for the experiments with a modified 0.8-NA Mirau objective. A detailed analysis of the low-coherence interference signals in the spatial and spectral domains reveals small differences between the two scan mode. However, the comparison of surface profiles of objects having surface departures smaller than the depth of focus shows no appreciable differences. We conclude that the small amount of defocus that affects interference signals recorded during an object scan does not influence the quality of the measurement when using typical broadband extended sources.

We have carried out wavefront aberration measurement with the reduction projection of an aperture on the pupil of the test microlens set in the interferometer optics. The size of the image of the aperture determines the effective aperture of the microlens, and proposes aperture restriction methods to reduce the influence of the Fresnel diffraction. Wavefront aberrations were measured and evaluated by the use of phase shift method applied to the Mach-Zehnder interferometer. We studied if we can form an image of an aperture stop on the pupil plane of the test microlens. The evaluation of the effect of the aperture on the fringe quality was evaluated through the prototype equipment using the microlens of less than 30 micrometers in diameter. In this paper, we describe the method of reducing the measurement error of wavefront aberration using the effective diameter of the microlens.

A distance measuring system and surface profiler with extended range based on collimation testing technique using lateral shearing interferometry is proposed. The sensor works on the principles of focus sensing and interferometry and the depth gating is achieved by collimation testing. A wedge-shaped shearing plate was used for the interferometer and when the object surface is exactly at the focus of the collimating lens the interference fringes are perfectly parallel to a reference line with a finite spatial frequency. If the object surface is out of focus of the collimating lens the fringe pattern is oriented with a change in the spatial frequency. The orientation of the interference fringes and their spatial-frequency increases as we move the object farther from the focused position. Fourier transform method for fringe analysis is used and from the maximum of the Fourier spectrum the distance and three-dimensional surface profile of the objects is measured. Since the surface profile is reconstructed from the maxima of the first-order Fourier spectrum, a large range of measurement without any fringe ambiguity problem can be achieved using the system. The system works both for smooth as well as diffuse objects and is compact, robust and inexpensive. A high-depth of resolution of the order of 10 micrometer achieved with a range measurement 10mm.

We describe here characteristic properties relating to the interferometrical measuring of microlens with an effective numerical aperture determined by the software or the hardware. Starting from the wave equation, both of the amplitude and the phase of propagating optical beams can be calculated using Hankel transformation anywhere through the interferometer. First introducing the effective aperture determined by the hardware including the method of projecting the effective aperture on the pupil of the microlens, the effect of truncation or diffraction with the effective aperture on the beam propagation is shown. Next using Mach-Zehnder interferometer combined with the effective aperture, the measurement of the wavefront aberration of test microlens is simulated to show that the imaginary aperture by the software settled on the image sensor which is located at the conjugate position of the test microlens is equivalent to the hardware determined effective aperture including projected one. Numerical results are presented to show the measurement errors stay within λ/100 for two typical test microlens of 38 μmΦ and 125 μmΦ with 1 λ wavefront aberration for aberration-free measuring optics with large enough numerical aperture.

Active systems are becoming more and more prevalent in the the field of optical technology. These systems require not only means of controlling wavefronts but mostly also of sensing wavefronts. This paper shows in four examples how spatial light modulators can be utilized to perform active wavefront sensing and wavefront controlling tasks. The examples include an interferometer with a flexible reference, a method to determine and compensate wave aberrations in focusing optical systems, an adaptive Shack-Hartmann sensor with a microlens array generated by a liquid crystal display and wavefront error compensation strategies with a piston micro mirror array.

Combining spatial and time-domain processing in wave-front measuring interferometers is a powerful tool for reducing the influence of environmental disturbances on the measurement. Modern digital imagers and computing platforms eliminate most of the disadvantages typically cited against spatial processing techniques. The ability to perform both spatial and time-domain processing in a single instrument provides the greatest flexibility for precision metrology applications in both static and dynamic environments.

A new illumination concept for fringe projection will be presented. Up to now fringe projection systems were based on reflective and/or transmissive microdisplays like digital micromirror devices (DMDs), nematic liquid crystals displays (LCDs) or liquid crystal on silicon displays (LCOS). But the size of the light source and of the illumination optic is a strong limitation for the miniaturization of the sensor system itself or for the integration in other illumination setups. Here we propose to use a high-brightness OLED-display (organic light-emitting diode) as active element for fringe pattern generation, giving the possibility to realize compact projection units.

Noncontacting measurement of roughness of solid surfaces by digital speckle correlation of video signals is reported. Speckle patterns appearing in the diffraction field of a laser-illuminated sample are taken by a CCD before and after the change of the incident angle and their cross-correlation peak is calculated as a function of the change from which surface roughness can be evaluated. The theoretical cross-correlation function is derived that describes speckle displacement and decorrelation due to the changes. In the theory the surfaces are assumed to affect only the phase of the incident light in proportion to surface profiles. The decorrelation curve against speckle displacement that is proportional to the change of the incident angle depends on the root-mean-square surface when it is larger than wavelength and when the correlation length of the roughness is much smaller than the spread of the incident beam. We developed an instrument that provides the decorrelation curve in a few tens of seconds by installing a real time correlation device based on phase-only-correlation algorithm. Various roughness standards of molded metal were measured with both the instrument and a stylus roughness meter. Good agreement has been observed between the results for the surface roughness between a few and a few tens of micrometers.

Based on the computer aided test technique, a precision method for measuring the comprehensive topography of the deep hole surface is developed. The measuring principle and data processing method are described in detail. A new built-up function has good linearity and good continuity, therefore it is easy to be subdivided by computer and the error can be corrected conveniently. In order to get a high quality fringe signal, we apply a new correction technique which based on the least square method to correct the A/D values in real-time. Some new methods are firstly employed to predict measuring errors and find the best measuring plan. A serial of experiments are made to verify the method’s availability and reliability by using some especial devices and software. Based on the laser holographic diffraction grating, a new experimental instrument is developed to measure the needle valve seat’s cone of a diesel engine.

Different interferometric techniques are required to cover most of the scientific needs in the field of fluid dynamics science in microgravity research. The Fluid Science Laboratory (FSL), currently under upgrade for the Columbus Orbital Facility of the International Space Station (ISS), shall provide Holographic Interferometry, Digital Holography, Electronic Speckle Pattern Interferometry (ESPI) and Shearing Interferometry among other diagnostic tools. On earth, these highly sensitive interferometers are operated in a thermal and mechanical controlled environment. In opposition to the situation on ground the multi-user facility of the FSL has severe constraints for what concerns volume, mass, modularity, operational needs and its environment. This results in a three-dimensional modular drawer structure for the design of the optical-mechanical set-up, where performance limitations must be expected compared to systems on ground. In a rather uncontrolled thermal environment onboard the ISS this leads to misalignment due to thermo-mechanical changes of the Aluminum structure during experiment runs which finally result in interferogram distortions and therefore to significant measurement errors. In this paper we report about a misalignment detection- and active compensation concept developed on the basis of a thermo-mechanical and optical analysis of the set-up. The detection system is based on a simplified Hartmann-Sensor. It is able to separate wave front tilt and curvature errors due to misalignments of the interferometers itself from the effects caused by the experiment. The closed-loop compensation system uses optical components of the set-up driven by piezoelectric actuators. Due to its active approach this concept allows for the real time accessibility of the experimental effects in the framework of “Telescience.” Extensive functional tests as well as representative thermal tests show the suitability of the proposed technique to compensate interferogram distortions due to thermal-mechanical deformations. Thus, it is able to ensure interferometric measurements with sub-wavelength accuracy onboard the ISS.

A design of a high-resolution homodyne interferometer is presented, modularized, and installed in a prototype, critical-dimension atomic force microscope (CD-AFM). A newly designed symmetrical layout of the optical path of the homodyne interferometers enabled highly stable measurements of the mechanical displacements of a wafer-positioning stage and an AFM scanner. In the performance measurement of the wafer-positioning stage, the mechanical drift after long-stroke travel and unlocking of the servo control was reduced to less than ten nanometers per minute by optimizing the preceding motion before stopping. An AFM scanner with a three-dimensional (3D) parallel spring structure has been implemented for the interferometer modules. Using a DSP-based electronic interpolation technique, displacement of the scanner was resolved and calibrated at better than 50 pm and 200 pm, respectively.

In interferometric length measurements the position of the sample with respect to the interference phase map is very important. Even the pixel resolution of the camera array may limit the measurement uncertainty, depending on the amount of the sample’s non-parallelism. In this case a correction can be applied taking into account a sub-pixel position at the sample’s front measuring face. In this paper three different methods are introduced which can be used for the definition of a sub-pixel central coordinate. Measurement examples illustrate that a value of 0.04 pixels for the standard uncertainty associated with the sub-pixel position seems realistic.

The important design factors that have to be considered for packaging of modules, which have single mode fiber (SMF), are mechanical failure and misalignment of the optical components (such as fiber, lens, laser diode and photo diode) during thermal loading. In this paper, the misalignment of single mode fiber and the strain in the optical module was measured for high temperature loading by Micro Moire interferometry. The experiments were performed on a module consisting of SiOB and single-mode-fiber attached in a V-groove with the help of a UV-curable adhesive. Temperature load ranging from room temperature (23°C) to 100°C was applied to the module. Maximum displacement of fiber in the vertical and horizontal directions relative to the SiOB was determined to be 0.69 - 1.21 μm and 0.36 - 0.42 μm, respectively at 100°C. The variation of the displacement for different samples at a given temperature was observed due to different initial position of fiber in the V-groove and the amount of adhesive around the fiber. Normal strain induced in the fiber was also calculated when the module was subjected to a temperature increment of ~75°C. Finally, a qualitative analysis was carried out for shear strain in different parts of the module and the maximum shear stress was observed at the silicon-adhesive-fiber joint region.

In this paper the basic principles of Low Coherence Speckle Interferometry (LCSI) are described. Theoretical background and experimental results for the systematic investigation of LCSI are presented. To understand and quantify the measurement results of adhesive bonded joints a modelling of the interference signal is required. For this purpose, a one-dimensional transmission line model is developed, including changes in the refractive index in a stressed adhesive layer and delamination of the glued interface. A new method for the detection of zero path length difference is introduced. Investigations of the probing depth in semi-transparent adhesive and recent experimental results of the characterisation of adhesive-bonded aluminium joints are presented.

Optical techniques for full-field displacement/strain measurement are a powerful set of tools for use in defining the performance, design optimization, reliability and safety of various types of components, products and machines. The quality of the measurement data generated by optical techniques is strongly dependent on the instrumentation and procedures. Thus, there is a significant need to develop standardized tests that are applicable across the spectrum of optical techniques of strain measurement. This requires the description of a common standard measurement chain including: (1) definition of standard physical and virtual materials; (2) gathering experimental or simulated primary data (fringe/image map); (3) deconvolution phase maps from these data (numerical procedures); (4) calculation of required physical quantities from phase maps (numerical procedures including data scaling). This scheme supports a calibration process for both instrumentation and procedures. Validation of this general methodology was performed using an example of displacement data gathered by grating interferometry followed by data processing scheme.

Moire interferometry is a high sensitivity tool for deformation measurement. Micro-moire interferometry (MMI) extends this into the micron-level spatial resolution. However, the information available in both cases is in the form of a deformation map, which needs to be differentiated to determine strains. The Optical Diffraction Strain Sensor (ODSS) directly provides strain information. This is generally a point-wise approach and scanning of the specimen is necessary to obtain full-field strains. At the same time, while strains are important, the deformation map is also relevant. Hence an integrated strain sensor is proposed. To overcome the scanning, a novel sensor scheme is proposed.

An out of plane optical sensitive configuration for pulsed digital holography was used to detect inhomogeneities inside semi solid organic materials. A loud speaker was employed to produce a mechanical wave that propagates through the material in such a way that it generates vibrational resonant modes and transient events on the material surface. Surface micro displacements were observed between the firing of two consecutive laser pulses, both for a steady resonant mode and for different times during the transient event. Two kinds of inhomogeneities were inserted approximately 2 cm inside the material diffracting the original mechanical wave and thus changing the resonant mode pattern or the transient wave on the surface. Comparison of phase unwrapped patterns, with and without inhomogeneities allows the rapid identification of their existence. The results for the resonant and transient conditions show that the method may be reliably used to study, compare and distinguish data from inside homogeneous and in-homogeneous organic materials.

Laser microwelding process produces large temperature gradients during the complicated phase transformations of workpiece materials, which results in a high stress level and undesired thermomechanical deformations. Characterization of these deformations becomes important as they might significantly affect performance, functionality, and reliability of the microwelded components. We have developed an optoelectronic holography (OEH) methodology for nondestructive evaluation of thermomechanical deformations caused by laser microwelding processes. OEH methodology provides a unique experimental approach for quantitative measurements of displacements and deformations with sub-micrometer accuracy in full field of view. In this paper, the OEH methodology is described including illumination of a workpiece, formation and acquisition of images, and processing of these images to determine parameters characterizing laser microwelds. Representative results of the OEH measurements of the deformations caused by laser microwelding of metal sheets are presented as a function of different laser welding parameters. In addition, analytical and computational models are also developed to simulate temperature, thermal stress, and thermal deformation fields in laser microwelding process. The investigations indicate that the OEH methodology is a viable tool for characterization of thermomechanical deformations caused by laser microwelding processes, and can help optimizing laser microwelding processes for high precision material-joining applications.

This paper presents a temporal speckle pattern interferometry (TSPI) system which uses thermal waves to detect internal defects. The system allows the measurement of out-of-plane thermoelastic displacements generated when a specimen is locally heated with a temporally modulated CO₂ laser. The defects can be detected by observing the perturbations which appear in the induced displacement field. Displacements are determined from the calculation of the optical phase distribution using a temporal phase shifting method and temporal phase unwrapping. The description of the TSPI system is followed by the presentation of experimental results that demonstrate that the detectability of certain type of flaws is improved by the use of thermal waves.

Nafion is widely used as the polymer electrolyte in proton exchange membrane (PEM) fuel cells. The properties that make the Nafion membrane indispensable are the combination of good water uptake, ion-exchange capacity, proton conductivity, gas permeability, and excellent electrochemical stability. The amount of water sorbed in the Nafion membrane is critical as the proton conductivity depends directly on the water content of the membrane which determines the fuel cell performance. The factors which affect the extent of the solvent uptake by Nafion are temperature, ion-exchange capacity, pretreatment of membrane, and the physical state of absorbing water, whether it is in liquid or vapor phase. The water sorption in the membrane is explained in terms of thermodynamic equilibrium of water in the vapor and absorption phases. As the membrane imbibes more water, the membrane matrix expands and exerts a pressure on the pore liquid which affects its chemical potential and limits extent of swelling. The extent of matrix expansion of the membranes depends on the elastic modulus, E, of the membrane, which directly affects the sorption. Hence, it is important to understand the variation of E for Nafion membrane with relative humidity (RH) and temperature. Optoelectronic holography (OEH) techniques are applied to perform quantitative, noninvasive, full field of view investigations to determine temperature and water activity dependence of E. The results obtained confirm that with the increase in temperature, E decreases and the membranes imbibes more water. Such results will allow optimization and realization of fuel cells with improved efficiency and performance.

Ceramic materials, in particular high temperature technical ceramics and refractories, are used in a wide range of temperature. Band and total emissivities of ceramics are needed for non-contact temperature measurements and for modeling of radiation heat transfer. If the spectral emissivities are known in a sufficient range of wavelength and temperature, the band and total emissivities for most applications can be calculated. At the University Duisburg-Essen an experimental setup for measuring of temperature-dependent spectral emissivities was modernized with a FT-IR-spectrometer. A remarkable quality improvement of the measurements could be reached. The spectral and temperature ranges of the measuring device are now 0.8 to 25 μm and 100 to 1200°C. In the paper a description of the measuring device will be given and selected examples of measuring possibilities of the spectrometer are shown. By the example of high temperature ceramics the obtained improvements of the device are presented for measured temperature-dependent spectral emissivities.

Development of target detection algorithms and simulation models for present and future multispectral and hyperspectral sensor systems requires accurate characterization of the reflectance and thermal emission of natural and man-made materials. Fourier transform spectrometry is one method for obtaining relatively high spectral resolution, in-situ measurements of surface reflectance. This paper discusses the performance characteristics of the SOC-400T FTIR and its application to field measurements. The SOC-400T is a relatively small and portable FTIR reflectometer that was designed to measure the directional reflectance and calculate the directional thermal emittance of surfaces in the spectral range from 2 to 25 ημm. The SOC-400T uses a silicone carbide glowbar to illuminate samples. This permits accurate results to be obtained in the MWIR. We recently deployed this instrument to the field to perform measurements on various materials of interest to the military. Prior to the deployment, the instrument was evaluated to assess its performance under true field operating conditions. This paper specifically examines noise characteristics, warmup time, transients induced by reorientation of the sensor, spurious detector artifacts, and sensitivity to vibration. We also address the practical issue associated with positioning, stabilizing, and calibrating the instrument for field measurements of irregular or arbitrarily oriented surfaces.

During the last decade we have performed theoretical investigations and successful experimental research demonstrating the existence of bulk strain solitary waves in nonlinearly elastic solid wave guides. However in the previous experiments we were limited by relatively short wave guides (up to 150 mm long), that provoked some doubts in that the observed waves were really solitary waves. Here we demonstrate new experimental results on soliton behavior in a much longer wave guide (up to 570 mm long) made of polystyrene. It is shown that even at so long distances bulk solitons do not exhibit any decrease of amplitude or shape changes when propagating in an isotropic wave guide. On the contrary any of linear or shock waves in these material disappear completely at much shorter distances. The obvious physical applications of strain solitons are connected primarily with potential generation of such waves in elastic constructions, that was not considered before in calculations of their strength, plasticity and damage threshold. The possibility to record variations of strain soliton parameters in long wave guides gives an opportunity to obtain data on nonlinear wave dissipation in these materials.

For dimensional researches and applications, the end standard measurements are the popular subjects in high precision standard systems or instruments. In general, the gauge blocks are the representative of the end standards. The universal measurement machines (UMM) are usually utilized for the dimensional length of gauge blocks. However, for measuring the dimensional lengths of test gauge blocks (TGBs), they should be compared with the same lengths of the master gauge blocks (MGBs). Thus, there are different lengths of the MGBs needed to be prepared and the measuring procedures are usually very time consuming. In order to lower the cost of procurement and maintenance of MGBs, a continuous end standard measurement system (CESMS) was built for many different test ranges of TGBs. The features of the CESMS included at least one gauge block, the LVDT probes for positioning, the real lengths of the TGBs measured from the display value of the laser interferometer, and total procedures controlled by automation software. All of these parts were integrated onto a large platform and its moving carriage could travel up to 1.2-meter in distance. Within these ranges, the CESMS could measure different dimensional lengths of the TGBs and many pieces at the same time. The CESMS utilized the laser interferometer to acquire the accurate display values between two ends when the LVDT probe was touched and triggered the automation software to record. Owing to the recommended radiation of laser head, the CESMS could be traced to the meter, SI unit. Furthermore, the experiment results showed that the comparison results of certificated gauge block at 800 mm suited for calibration certificate by PTB.

In this paper we present phase shifting Talbot interferometric technique to draw the profile of the gas turbine blade. In Talbot interferometry phase shifting is implemented by giving in-plane translation to first grating by using precision translation stage. To obtain the phase connected with the object, the additional phase change stepwise, with a step of π/2 at least three times is introduced and the intensity patterns corresponding to these steps are recorded as Talbot interferometric fringes pattern. Experimentally recorded interferograms have noise due to grating lines and speckles. These noises are filtered by using Fourier filtering technique. The phase map made by using Fourier filtered data. Height variations/profile of the gas turbine blades made by using phase shifting Talbot Interferometry are compared with the results obtained from Co-ordinate Measuring Machine (CMM) having coordinate measurement facility with the resolution of 1μm. The results are in good agreement.

We present an experimental module on electromagnetically induced transparency (EIT) in a Hanle configuration aimed to application for precise metrology. The EIT line width of the order of hundred hertz equivalent to nano-Tesla magnetic flux density has been achieved in rubidium atomic vapors with Ne buffer gases at room temperature. It can be interest for build of EIT based all-optical compact magnetometers, competitive to the most sensitive magnetometers based on superconducting quantum interference devices.

A new interferometric vibration sensor for testing both vibration and subsidiary resonance that have detrimental effects on the servo performance of the optical pickup actuator is presented. Experimental results of slim optical pickup actuators obtained from the sub-resonance tester such as the interferometric vibration sensor are presented. It can be also used for other applications in the R&D domain and production environments with a low price and compact size.

We have studied wave curl structures created behind the shock wave as it expands beyond the edge of the shock wave tube. A description of a large-scale shearing interferometer used for these studies is presented. A technique for quantitative automated analysis of the shearing interferograms is developed, which is well suited for registration of the interferograms using CCD sensors and data processing using PC. Physics of the gas-dynamics processes is analyzed. Main quantitative parameters of the gas are presented.

In this paper an algorithm to measure large deformations using digital speckle pattern interferometry is presented. It facilitates recording of large number of frames and can subtract them to display speckle correlation fringes with improved signal-to-noise ratio. To further improve signal-to-noise ratio a filtering scheme is also presented by using average/median filtering followed by wavelets filtering. Experimental results and analysis are presented in detail. For a typical displacement of 200 μm, error in measurement was less than 1.5 percent. Range in measurement is governed by change in scattering property of the surface of the object.

In this paper the study of out-of-plane or transverse vibrations in a square plate using digital speckle pattern interferometry (DSPI) is presented. To improve the accuracy of measurement, earlier we have suggested filtering scheme based on proper use of average/median filters followed by Symlet wavelet filter. In this paper we present a different filtering scheme to reduce the speckle noise and improve the accuracy of measurement of DSPI fringes by proper choice of average filter, sampling and thresholding followed by Symlet/Biorthogonal wavelet filter. The speckle index of filtered pattern is calculated and compared with speckle index of unfiltered fringe pattern. It is observed that speckle index is significantly reduced after filtering the DSPI fringe pattern. Experimentally obtained resonance frequencies for the square plate for the boundary condition fixed at all edges were compared with that of classical theory for thin plates. The resonance frequencies obtained from DSPI show good agreement with that of obtained from the classical theory.

The Ronchi test is one of the simplest and most effective methods used for evaluating and measuring aberrations. Employed in optical shops, its use is limited to qualitative analysis. Few methods in use today produce quantitative results. What follows are explained both the development and the guidelines for manufacturing a Ronchi tester based on quantitative analysis which also has the advantage to receive automatic input and output of data. In order to achieve this goal, phase shifting interferometry and a square Ronchi ruling with a variable intensity LED were used. It is important to note that with the set up described only one movement of the motor which supports the square ruling is needed to simultaneously obtain both the X and Y components of the wave front aberration.

In the paper a new method for scaling of phase values into (x,y,z) co-ordinates supporting methods with absolute phase determination e.g. fringe projection/Gray code techniques is presented. It is based on calculation of characteristic polynomials describing relationships between phase values and real (x,y,z) co-ordinates in measurement volume. Coefficients of these polynomials are calculated on the base of phase distribution of known calibration model. Applicability of the method described is proven by calibration of 3D shape measurement system based on unknown, commercially available projection and detection systems with unknown parameters of imaging optics and geometrical set-up. Exemplary measurement results of technical and freeform objects are presented.

A very broad field of relevant technologies and testing methods for silicon micromechanical elements had to be limited to specific elements and adapted methodologies including experimental and numerical methods. In particular, the bimorph micromembranes under buckling are key elements for investigations of their mechanical properties. Due to optical quality of silicon-based layers deposited on micromechanical devices under consideration, the two-beam interferometry with computer interferogram processing is well adapted for shape and deformation measuring, while the nanoindentation is able to extract the hardness as well as the Young’s modulus. In this contribution, we investigate the silicon square membranes prestressed by deposition of silicon oxinitride (SiO_xN_y) films fabricated by PECVD. The combination of experimental techniques with fine elements method (FEM) proposed here offers a powerful tools for investigation of residual stress of SiO_xN_y layers. The distribution of residual stress is monitored as a function of the refractive index of SiO_xN_y films, establishing the correlation between the optical and micromechanical properties of deposited thin films.