A rugged optical method has been designed for making measurements in a hostile industrial environments such as the combustion exit flow ofa gas turbine engine. Typically the gas temperature in such a combustor is 1000 K and the speed of the flow 700m/s. A transient shock tube has been constructed at MET (Massachusetts Institute of Technology ). The objective being to simulate the mixing rate for different types of exit combustor exit nozzles. A direct particle visualisation approach has been developed combining a c/w Argon/ion laser and an electronically shuttered image intensifier. The combination has been used measure the density distribution average over the complete 3ms run time ofthe transient shock tube facility. The system also has the potential to measure the entrainment of the surrounding ambient air and make velocity measurements.

A new holographic technique has been developed to measure displacement in solid and fluid mechanics. The method uses double exposure holograms of large numerical aperture to record the light scattered from a solid surface or seeding particles that are assumed to follow the fluid motion. Analysis of the resulting hologram is performed in a piece- wise fashion through spatial correlation of the field that passes through a sampling aperture placed in the real image. In this way it is possible to map 3D displacement of an irregular surface or map the movement of seeding throughout an extended volume of fluid. This paper discusses the cancellation of gross aberrations using a phase conjugate holographic optical element to generate a converging reference wave. Seeded flow or solid surfaces recorded with this reference wave geometry can be reconstructed efficiently using a fiber-optic probe. In addition to aberration cancelling the technique allows a method of image shifting to be introduced thus resolving the direction of the flow or surface displacement.

A thorough understanding of turbulent reacting flows is essential to the continued development of practical combustion systems. Unfortunately, these studies represent a tremendous research challenge owing to the inherent complexity of such flows. In an effort to reduce the complexity of these systems while capturing the essential features that define the physics and chemistry of turbulent reacting flows, we have been studying the interaction of a vortex with a laminar flame. The experimental apparatus includes a piston-cylinder device configured to provide a controlled toroidal vortex. The generated vortex/jet interacts with a nonpremixed hydrogen-air flame supported in a counterflow burner. The counterflow configuration permits precise selection of the flame and the associated strain field. Vortex characterization is essential to interpreting the experimental observation and accomplishing numerical modeling of vortex-flame interactions. Two-color particle- image velocimetry (PIV) has been employed to characterize the vortex and to describe the underlying counterflow velocity field. The hydroxyl (OH) layer produced by the flame is imaged using planar laser-induced fluorescence (PLIF). The PIV and PLIF measurements of OH are performed simultaneously. A distinct annular extinction of the OH layer is observed, in good agreement with previous computational modeling predictions for the apparatus.

It is still one of the main problems to observe and measure the non-steady and spatial complex flows for the fluid mechanics. Except 2D-PIV and SPIV, the holographic particle image velocimetry (HPIV) is one of the approaches to measure instantaneously the three component velocity vector field in a full 3D volume. In this paper, the displacements of the particle sin a volume of the flow was recorded instantaneously by a holographic recording system which was designed and tested specially.

A novel method of measuring the probability density of velocity differences in turbulent flow is described. The method is based on the light-scattering technique known as homodyne correlation spectroscopy. Using fiber optic probes to image two different scattering volumes in a turbulent fluid, it is possible to recover the probability density function of velocity differences without invoking Taylor's frozen turbulence assumption. The design of the instrument is described, together with the optical alignment procedure. Some of the fundamental limitations to the accuracy of the technique are discussed. Measurements of the pdf from uniform and turbulent flow are presented, where the turbulence was generated using a mechanical stirrer in a beaker of water.

There are many well-known tomographic methods for the determination of physical quantities in a 2D or 3D space. Most of these quantities are scalar or vectorial. In this paper, a novel method is presented to determine a tensorial quantity in a 3D space: The determination of the 3D stress tensor and of the 3D refractive tensor in photoelastic materials is achieved by applying otpical tensor field tomography. The theory of the projection is described, and the principles of two reconstruction algorithms are explained. The experimental setup is presented, and difficulties in measuring the projections are described. Finally, experimental results are shown.

In order to understand 3D transient flow, it is very essential to apply holographic interferometric tomography. The technique is also advantages in providing nonintrusive measurement capability with reasonable accuracy and spatial resolution. Here, a new computational tomographic algorithm which is termed as Curvilinear Nonlocal Basis Function Method is introduced for reconstruction of flow fields. It is appropriate for reconstruction under various ill-posed conditions involving a limited view angle and an opaque object inside a field with irregular boundaries. The reconstruction technique is tested through computer simulation of experiments as well as a real 3D flow field. The results presented here demonstrate reliable measurement accuracy when the technique is applied for reconstruction of transient 3D flow.

The line-of-sight speckle photography of transparent media is used for quantitative measurements of the instantaneous temperature fields in 3D unsteady flows. Both electronic and photographic methods are employed for specklegram recording. The subsequent specklegram treatment uses the Young's fringes method as well as the cross-correlation analysis of small interrogation regions of the recordings. For laminar flows, the local and global Nusslet numbers were determined via measuring local surface temperature gradients for convective heat transfer from vertical isothermal plates of different configurations. The results were compared with Ostrach's theory and with data obtained by Mach-Zehnder interferometer. The 3D temperature fields were reconstructed for axisymmetric convective flows around a suddenly heated vertical wire using single projection measurement and Radon inversion. For turbulent flows, the temperature field microstructure was analyzed with the help of the correlation and structural functions. The 2D correlation function (CF) of the deflection angles of probing light was transformed into 3D CF of temperature field using Erbeck-Merzkirch integral transformation. Both macro- and microscales of turbulence were evaluated using this CD. The variation of the turbulence microscales due to interaction of turbulence with a shock wave was studied and analyzed.

In this paper a mathematical model for a laws of laser speckle movement in space when light beam pass through a phase object is proposed by using the Fresnel-Kirchhoff diffraction integral. By means of the theoretical analysis for this mathematical model, the following three conclusions can be got. First, when a light beam passes through a phase object, for example a transparent flow fluid, the movement state of speckles in space depends not only on the characteristic function on surface of speckle sources, but also on infinitely small variation of propagation direction of incident beam. If the characteristic function can be kept same during a double exposure, then the movement states of speckle in space and their corresponding speckle displacements depend only on the variation of propagation direction of incident beam. Second, to make the characteristic function same during a double exposure the considered light beams which produce a pair of correlation speckles must come from the same space zone on the surface of speckle source. Third, when a light beam passes through a diffusion surface, the variation of propagation direction of the beam can not be determined by the principle of geometrical optics because of scatting function of light beams on diffusion surface. But the principle of geometrical optics still can be used in discussion of the movement states of speckle in space and in determination of speckle displacements according to the mathematical model proposed in this paper. Above these analysis provides a theoretical basis for designing experimental arrangements of laser speckle photography in flow visualization. According to the laws of laser speckle movement in space six different experimental arrangements which can be used in flow visualization are presented. The formulas of processing the experimental data for measurement density field and temperature field in flow fluid are given. These results are very favorable for development of laser speckle photography technology in flow visualization.

With the rapid advancement of today's ultra-high performance mechanical or mechatronic system such as magnetic or optical disk drives, improving metrology capabilities to examine the performance characteristics of these system are growing ever more important. The primary tested studied in this paper is an ultra-high precision ball-bearing spindle that possesses non-repeatable runout of less than 100nm. The metrology tool adopted is laser Doppler interferometer system that has Megahertz bandwidth and nanometer resolutions. Experimental data obtained clearly indicates that measuring vertical runout of a spindle motor is a straightforward process. However, a fundamental effect was identified, where the radial runout data was found to drift upward or downward with time, when using the laser Doppler system to measure the radial runout of ultra-high precision rotational systems whose surface profile is not flat. All of the underlying reasons that cause this undesirable effect were proposed and verified. Approaches that can be adopted to circumvent this apparent limitation on adopting the laser Doppler interferometer systems to measure rotational curved surface were implemented to further extend its application horizon. The experimental data realized and the application experience obtained were shown to further advance our measurement capabilities.

Particle tracking is an essential step in data process of stereoscopic imaging velocimetry. It is known that in particle tracking velocimetry, part of the individual particle images or equivalently data points are likely to be lost when a flow field is seeded with a high-density particles. In order to maximize the data point-recovery and to enhance the measurement reliability, the neural networks are employed to attain a globally-optical solution in finding appropriate particle tracks. Our investigation indicates that the neural networks offer very good potential for performance enhancement and has proven to be very useful for stereoscopic imaging velocimetry.

Qualitative comparisons are made between Particle Image Velocimetry data and Computational Fluid Dynamics predictions for the flow around two adjacent rotating cylinders. For this novel flow configuration, the cylinders rotate in opposite directions with their outer surfaces in contact. Steady state sets are carried out of the following rotational Reynolds numbers, Re_(phi ) equals 75, 966 and 1470. Also, test are carried out where the cylinders are suddenly started. The flow exhibits a relatively powerful jet which is ejected between the cylinders. Under transient conditions a complex flow phenomenon is observed. A numerical stochastic Lagrangian particle transport technique for studying the movement of seeding particles relative to fluids is used. Under steady conditions agreement is found between measurements and predictions.

This paper describes a new 3D surface contouring system based on a digital fringe projection and phase shifting technique. The new system takes full advantage of a novel projection display technology to provide the capability of digital fringe projection with high brightness and contrasts ratio. This capability helps improve system resolution and accuracy and make the full-field contouring of large objects possible. Fringe patterns with any cross-sectional intensity profile and spacing can be created digitally by software on a computer, limited only by the resolution and bit depth of the projection system. Also, purely software-based digital phase shifting technique can be applied to improve the resolution of the contouring technique. This eliminates the need for physically shifting the grating or other optical components and makes phase shifting digitally accurate. The concept of this new 3D surface contouring system is first introduced. Then issues related to projector nonlinearity, background noise, and phase unwrapping are addressed. FInally, some experimental results are presented.

This paper introduces a new approach to 3D displacement and velocity measurements that unifies the disciplines of holographic interferometry and holographic particle image velocimetry (HPIV). Equally applicable to fluid and solid mechanics, the overall system enables quantitative displacement measurements between two holographically recorded events from either particle or surface scattering sites, working with both pulsed and continuous-wave laser systems. The resulting measurements exhibit an accuracy corresponding to interferometric system, but with a dynamic range found with PIV systems. Most importantly, this paper introduces the novel use of an optical fiber to specify the measurement points, remove optical aberrations of windows, and eliminate directional ambiguity. An optical fiber is used to probe the recorded holographic image space at each 3D measurement point in order to extract the 3D displacement vectors. This fiber system also employs a novel optical image shifting method to eliminate the problem of directional ambiguity. In addition, the reported system uses 3D complex optical correlation rather than 2D real digital correlation. It is therefore a simple matter to directly obtain 3D displacement and velocity measurements at precisely known 3D locations in the object space. By correlating both the amplitude and phase information in the holographic image, this system can measure spatial distributions of displacements even when the presence of severe aberrations preclude the detection of sharp images.

In a fiber-optic multi-point sensor network basing on optical fiber Bragg gratings, simultaneous measurements of refractive indices and of temperature are performed. The Bragg wavelength of a side-polished fiber grating is determined by the refractive index of the surrounding fluid, and is measured using a high-resolving low-cost compact spectrometer. The influence of temperature is separated considering the temperature-induced Bragg wavelength shift in an adjacent non-polished part of the fiber grating. The sensor network can be applied for on-line process control in chemical, biochemical and petrol technologies, and for environmental and geotechnical monitoring, especially in flammable or corrosive surroundings, and in electromagnetic fields. A buffer layer between fiber core and analyte allows to adjust the sensor characteristic to appear with high sensitivity in the refractive index range of the interesting fluids.

Holographic interferometric tomography has been used to reconstruct the 3D temperature field around a single isothermal cube in an infinite medium, which is under ill- posed reconstruction conditions of restricted scanning and incomplete projection. A reconstruction algorithm, termed the variable grid method, has been employed to improve the reconstruction under the ill-posed conditions. The heat transfer results are presented in terms of the average Nusselt number and the face-average Nusselt numbers at the top, bottom, and side walls of the cube. Some heat transfer results are also compared with those previously reported. The study demonstrates that the interferometric technique is applicable to measurement of convective heat transfer of reasonably complex, 3D fluid flow.

A non-contact thermometry technique has been developed to characterize the thermal state of silicon wafers during rapid thermal processing. Information on thermal variations is obtained from the dispersion relations of the propagating waveguide mode excited in wafers using a non-contact, broadband optical system referred to as Thermal Acousto- Photonics for Non-Destructive Evaluation. Variations of thermo-mechanical properties in silicon wafers are correlated to temperature changes by performing simultaneous time-frequency analyses on Lamb waveforms acquired with a fiber-tip interferometer sensor. Experimental Lamb wave data collected for cases ranging from room temperature to 400 degrees C is presented. The results show that the temporal progressions of all spectral elements found in the fundamental antisymmetric mode are strong functions of temperature. This particular attribute is exploited to achieve a thermal resolution superior to the +/- 5 degrees C attainable through current pyrometric techniques. By analyzing the temperature-dependent group velocity of a specific frequency component over the temperature range considered and then comparing the results to an analytical model developed for silicon wafers undergoing annealing, excellent agreement was obtained. Presented results demonstrate the feasibility of applying laser-induced stress waves as a temperature diagnostic during rapid thermal processing.

Proximity focused microchannel plate image intensifiers (MCPIIs) with a mesh underlay photocathode are analyzed for their irising time. It is found to be of the order of 650 ps for early prototypes. This is much longer than previously reported but is finally explained by the mesh thickness. Increased metal layer thickness provides highly nonlinear increase of mesh conductivity. Modified tubes show irising below 100 ps. It is expected to be only limited by its theoretical 40 ps minimum time caused by the propagation speed of the electrical field strength's change. A newly introduced impedance match has real broadband characteristics, and the irising is fully caused by other effects. The minimum gate time observable was clearly below 1 ns. The earlier investigated prototype mesh underlay MCPIIs did not open to its full diameter at the shortest applied times. Ni underlay photocathodes were analyzed for comparison. They also provide irising times down to 200 ps. The long laser diode pulse and a too flat voltage slope of the driving generator prevented exact results for subnanosecond gate timing. Continued development of the system is underway.

This paper reports the use of a new holographic measurement system in the study of 3D surface displacements. Although equally applicable to fluid and solid mechanics, the aim of this report is to demonstrate the system's use in quantitative surface displacement measurements with a classical cantilever experiment, using a continuous-wave diode-pumped YAG laser system. The reported results exhibit an accuracy corresponding to other interferometric systems, but with a much larger displacement range. The measurement system employs a novel optical image shifting method to eliminate the problem of directional ambiguity. In addition, the reported system uses 3D complex correlation rather than 2D real correlation, thereby offering a direct method for measuring 3D displacement in 3D space. FInally, with the novel use of an optical fiber to probe the recorded holographic image space, it is found to be a simple matter to directly obtain 3D displacement measurements at precisely known surface locations.

Video Model Deformation (VMD) and Projection Moire Interferometry (PMI) were used to acquire wind tunnel model deformation measurements of the Northrop Grumman-built Smart Wing tested in the NASA Langley Transonic Dynamics Tunnel. The F18-E/F platform Smart Wing was outfitted with embedded shape memory alloys to actuate a seamless trailing edge aileron and flat, and an embedded torque tube to generate wing twist. The VMD system was used to obtain highly accurate deformation measurements at three spanwise locations along the main body of the wing, and at spanwise locations on the flap and aileron. The PMI system was used to obtain full-field wing shape and deformation measurements over the entire wing lower surface. Although less accurate than the VMD system, the PMI system revealed deformations occurring between VMD target rows indistinguishable by VMD. This paper presents the VMD and PMI techniques and discusses their application in the Smart Wing test.

White light scanning interferometry generates short coherence interferograms whose fringe visibility is narrowly localized along the scanning dimension so that the optical path difference between the test and reference beams can be scaled without 2(pi) -ambiguity. Much attention has been paid during last two decades to the 3D surface mapping using white light scanning interferometry, and as results, quite a few noble different techniques are available in the published literature. The techniques differ from each other in the intricate way of fringe data processing, but just about all of them are effective in measuring top profiles of opaque surfaces with nanometer precision. However, when the surface is coated with transparent thin films layers, multiple reflections occur from the boundaries of film layers to produce complicate overlapped interferograms which are not readily treated by the existing techniques. The thickness measurement technique presented in this paper is as an extended version of the frequency domain analysis of white light interferometry. Special attempt is made to provide a means of interpreting interferograms of multiple reflection so that physical properties of thin film layers are precisely identified utilizing sampled phase distribution in the spectral frequency domain. In conclusion, the technique is capable of not only probing thickness point by point but also providing complete volumetric film digitized in three dimensions.

The development of a time-division-multiplexed 3D digital shearography instrument is described. The system provides simultaneous measurement of the in-plane and out-of-plane deformation gradients, allowing full surface strain analysis. The object under investigation is sequentially illuminated from three directions by three fiber coupled high power laser diode sources, and imaged onto a CCD camera through a single shearing interferometer. The pulsing of the sources is synchronized with the camera frame rate. Phase stepping is achieved using laser diode wavelength tuning combined with a path length imbalance in the shearing interferometer. The source pulsing schedule and image acquisition are controlled from a PC. An analysis of the optimum illumination geometry is presented. The performance of the system is evaluated on laboratory test samples.

A real-time holographic interferometer has been developed for quantitative flow and wavefront diagnostics. The interferometer employs a new variety of the non-linear recording material, Bacteriorhodopsin, to not only record interferograms in real-time, but to analyze them in real- time as well, using an innovative adaption of Phase Shift Interferometry. The versatile interferometer can be configured as a real-time holographic interferometer for general applications and also as a high-speed, multiple pulsed interferometer for time differential applications, such as analyzing unsteady flow and turbulence. The versatility and relative low cost of the hardware components make the interferometer an attractive option for upgrading current schlieren flow visualization systems.

A new unconventional interferometric technique that may be termed 'the reference process technique' is proposed for measuring the characteristics of complex heat transfer. It does not involve mathematical calculations almost. As example of its application the result of measurement of heat transfer characteristics form compact high power thermal energy source is presented.

Evolving ideas of how high pressure atomization occurs, why it occurs, and what parameters might have a significant influence on atomization present some new and interesting challenges for measurement system. Of particular interest for transient fuel sprays is the region near the fuel injector tip itself, where the spray seems to begin the atomization process. This region of a spray is generally optically dense, has a large number of ligaments and non- spherical liquid elements, and probably has a large number of droplets as well. The high number density of liquid elements as well as absorption in the liquid makes optical probing of this region difficult. Reliable data in this region of the spray would be very useful for better understanding of the atomization process in these systems, as well as providing data for model validation for computer models being developed to approximate this behavior. This paper will try to briefly review the most common droplet sizing methods currently used with an emphasis on their performance in dense spray regions.

A simple coherent interferometric processing method for image subtraction in real-time is presented. The proposed method is based on interferometric principle using Mach- Zehnder interferometer. The phase reversal is accomplished by varying the pressure within an air-filled quartz cell inserted in one of the arms of the interferometer. Initially, the interferometer is aligned to obtain broad interference fringes in the cell region. Then the input imageries are introduced in both the arms of the interferometer and adjusted for exact registration as seen in the plane of observation. By introducing a phase change of (pi) -rad between the two arms of the interferometer, the difference between the inputs is detected in real-time on the monitor. Phase shift calibration and information processing of the proposed method is presented with the results.

Quantitative measurements of shapes, displacements and deformations of opaque objects, as well as of refractive properties of transparent media, through spatial and temporal fringe patterns analysis is done by applying two basic techniques. The first one is the phase modification technique. The second one is the Fast Fourier Transform technique (FFT), assisted by some sort of heterodyning. FFT is also the choice for a single frame, not-modified, interferogram analysis. In this case however, because the lack of a spatial carrier, the sign of the phase cannot be determined. A solution to this problem is a technique that requires only two phase-shifted interferograms. In this paper we propose a holographic interferometry method based on wavelength multiplexing in which no spatial carrier neither second, phase shifted interferogram is required. Using the Lippmann-Denisyuk single beam holographic setup, an interferogram form a deformable object is recorded with multiple laser wavelengths in a panchromatic emulsion. A reconstruction of the 3D object in colors is observed, superimposed with a multicolor fringe pattern. The object phase is then computed from the multiple single-wavelength fringe patterns, allowing the measurement of the object deformation. This work is aiming at quantitative analysis of highly dynamic objects.

A refinement of a regional phase unwrapping technique that is driven by an integrated expert system is described. The traditional phase unwrapping algorithms used for phase shifting and Fourier transform is very noise-dependent and frequently unsatisfactory for heavily noise-ridden interferograms. THose methods that try to get rid of noises are too passive and limited. The developed method actively eliminates noises by using algorithmic as well as knowledge- based, intelligent approaches in constructing sound, not- distorted 2(pi) jump lines that divide an entire image into regions. Then regional phase unwrapping is performed region by region by adding or subtracting adequate 2(pi) multiples. The integrated expert system can correct noisy data on the iso-phase lines and the regional phase unwrapping algorithm isolates noises inside the regions without propagation.

This paper presents an interferometer which has been developed for real time quantitative refractive index measurements at video rate. A theoretical accuracy analysis of the measured phase distribution is presented for linearly stratified refractive index profiles. The interferometer is characterized experimentally. Therefore, phase distributions generated by a tilted mirror are measured by the real time interferometer and a common interferometer which contains a piezoelectric transducer.

The next generation of ga turbine combustors for aerospace applications will be required to meet increasingly stringent constraints on fuel efficiency, noise abatement, and emissions. The power plants being designed to meet these constraints will operate at extreme conditions of temperature and pressure, thereby generating unique challenges to the previously employed diagnostic methodologies. Current efforts at NASA Glenn Research Center GRC utilize optically accessible, high-pressure flametubes and sector combustor rigs to probe, via advanced nonintrusive laser techniques, the complex flowfields encountered in advanced combustor designs. The fuel-air mixing process is of particular concern for lowering NO_x emissions generated in lean, premixed engine concepts. Using planar laser-induced fluorescence we have obtained real- time, detailed imaging of the fuel spray distribution for a number of fuel injectors over a wide range of operational conditions that closely match those expected in the proposed propulsion systems. Using a novel combination of planar imaging of fuel fluorescence and computational analysis that allows an examination of the flowfield from any perspective, we have produced spatially and temporally resolved fuel-air distribution maps. These maps provide detailed insight into the fuel injection process at actual conditions never before possible, thereby greatly enhancing the evaluation of fuel injector performance and combustion phenomena.

A fluorescence sensor-system has been proposed that integrates optical and electronic components in a thin-film geometry. Predicted properties of this sensor include: increased sensitivity, shielding form unwanted radiation, wavelength filtering, potential operation at high temperatures, and miniaturization. The sensor can be tuned to measure a wide variety of species by varying its thin- film corrugation period. The optical properties of the sensor are determined, in large part, by optical cross coupling through a corrugated metal film and enhanced fluorescence. Measurements evaluating these processes are presented.

A result of experimental investigation for ignition process of transparent solid propellant models are presented. The investigations have been made by holographic interferometric technique in terms of ignition process visualization in the condensed and the gaseous phases of burning samples as well as qualitative analysis. This technique has not been used earlier by other investigators in the solid ignition process research, however examples of partly analogously investigations are known.

Spark-ignition systems play a critical role in the performance of essentially all gas turbine engines. These devices are responsible for initiating the combustion process that sustains engine operation. Demanding applications such as cold start and high-altitude relight require continued enhancement of ignition systems. To characterize advanced ignition systems, we have developed a number of laser-based diagnostic techniques configured for ultrafast imaging of spark parameters including emission, density, temperature, and species concentration. These diagnostics have been designed to exploit an ultrafast- framing charge-coupled-device (CCD) camera and high- repetition-rate laser sources including mode-locked Ti:sapphire oscillators and regenerative amplifiers. Spontaneous-emission and laser-shlieren measurements have been accomplished with this instrumentation and the result applied to the study of a novel Unison Industries spark igniter that shows great promise for improved cold-start and high-altitude-relight capability as compared to that of igniters currently in use throughout military and commercial fleets. Phase-locked and ultrafast real-time imaging strategies are explored, and details of the imaging instrumentation, particularly the CCD camera and laser sources, are discussed.

This study first describes the construction of casing- mounted single core fiber optic sensors for in-situ vibration measurement by blade tip timing. The design enables efficient use of light flux in a stand-off configuration, suitable for application in high temperature turbines. A description of laboratory experiments then follows showing how very high precision timing can be achieved by cross correlation of repeating speckle signatures from the blade tips. This has enabled the relative position of blade tips to be determined to better than +/- 2 micrometers when the maximum rotational speed was 4000 rpm. The requirements of an optoelectronic system for use at higher speeds and with the same precise timing is evaluated.

This paper reports holographic measurements of full-field 3D flows inside a production geometry 4-stoke internal combustion engine with extensive optical access through both the cylinder wall and the piston crown. The seeded flow is recorda at two instants as a reflection hologram of high numerical aperture. A purpose built holographic camera using a phase conjugate holographic optical element is used to compensate for the gross aberrations caused by imaging through a thick walled, glass cylinder. Fiber-optic, conjugate recognition and subsequent correlation of the complex amplitude recorded by the hologram facilitates sub- wavelength measurement of particle displacement without directional ambiguity. Preliminary measurements of the flow field within the cylinder at the bottom of the induction stroke are discussed. The results clearly show the potential of this technique to extract 3D velocity information in hostile environments.

The heat expansion of the solder joint on a PCB board has been investigated using speckle interferometry. Set-ups for measuring in-plane and out-of-plane displacements have been separately used. The component was stepwise heated by increasing the working current. During the heating the temperature was measured by a thermocouple. For each step, the heating was halted until thermal equilibrium occurred, then four phase-shifted interferograms were recorded for each temperature T_n. In this way the deformation between two temperatures T_n+1 and T_n were evaluated. The deformation was measured in different directions and the joint solder's strains were calculated.

Micro-cluster formation of the non-magnetic and ferromagnetic particles in a magnetic fluid was investigated. Using an optical microscope system with cardioid condenser lens, real-time visualization of the Brownian motions of both particles were carried out. The chain-like cluster formation of both particles were observed simultaneously under the magnetic field. Two types of magnetic fluid of a water-based and kerosene-based magnetic fluids were used as test liquids.

For detecting photo-induced refractive index changes directly in chalcogenide fibers, a heterodyne interferometer with a linear frequency modulated laser diode as light source is reported. Such technique can be employed in fabrications of both transmission and Bragg gratings in different kinds of fibers.

The phase continuous scan technique is combined with the Bessel fringe-shifting technique to quantitatively analyze the vibration mode by time-averaging DSPI. Through the phase continuous scan, the background and speckle items are completely eliminated, which improves the fringe quality and enhances the signal-to-noise ratio of interferogram. There is no need to calibrate the optical phase-shifter exactly in this method. The anti-disturbance capability of this method is higher than that of the phase-stepping technique, so it is robust and easy to be used.

A new error-correcting algorithm of phase unwrapping is proposed in this paper. This method can eliminate the propagation of phase errors in the unwrapped phase map. It is simple, effective, and has been successfully used in the deformation measurement and the quantitative analysis of vibration mode by DSPI.

The IR scene projector consisted of resistor array is an important device in the IR simulation technology. An enhanced version of the resistor array is currently under development. Thermal radiation characterization is necessary for the performance evaluation of the device. The resistor and its array are tested by the microscopic set of a thermal video system. The dependence of the radiation temperature on control voltage, the radiation power of the resistor, the uniformity of the radiation temperature, as well as the dynamic characteristic have been measured. An evaluation of thermal radiation characteristics of the resistor array has been provided. At the same time the effective emissivity of the resistor has been measured to obtain the true temperature distribution. It is possible to be used to improve the thermal design of this device.

Thermal imaging technique has been used to measure the temperature distribution of gas flow with high temperature and high speed generated in a high temperature wind-tunnel. FIrst, the silicon carbon sheath of thermocouple sensor was considered as a reverential body and its surface temperature was measured using a thermal-video system. The, the real temperature distribution of gas flow was calculated according to the convective heat transfer coefficient between the reverential body and the gas flow. Two ways have been sued to determine the convective heat transfer coefficient, one by calculating based on empirical relation, other by experimental way.

This article presents a new method which obtain 3D data of the complex parts or its CAD model based upon the material removal process and each cross-section optical scanning process of the parts. The advantages of this method is that the internal and external profile information of the complex parts can be capture data the same precision, the 3D data and 3D CAD model is acquired through the 3D CAD/CAM package. Examples of such structure described in this paper. In addition, the 3D digitizer is made with an existing CNC milling machine and an image scanner. Its highest accuracy of 2D edge detecting is 5.4micrometers , and the resolution is 2.7micrometers .

A new approach to the measurement of ultrasonic vibrations has been developed at the INEEL. This system utilizes heterodyne interferometric detection in a photorefractive material to provide real time, full field images of ultrasonic vibration amplitude and phase without scanning. The INEEL Laser Ultrasonic Camera has linear response for ultrasonic displacement (xi) < (lambda) divided by 4(pi) , approximately 45 nm displacement at a laser wavelength of 532 nm. In addition, the system exhibits flat response and narrow band detection for a broad range of vibration frequencies. The system is very robust, and has the potential for operation even in noisy industrial settings. A description of the system, representative data and several potential applications will be presented.