A high resolution Amplitude Modulated Imaging Laser Radar (AM-LR) sensor has recently been developed, aimed to accurately reconstructing 3D digital models of real targets - either single objects or large amplitude complex scenes. The system sounding beam can be swept linearly across the object or circularly around it, by placing the object on a controlled rotating platform. Both intensity and phase shift of the back-scattered light are then collected and processed, providing respectively a shade-free photographic-like picture and accurate range data in the form of a range or depth image, with accuracy depending mainly on the laser modulation frequency. The development of software, suitable for simultaneous 3D rendering of the intensity and absolute distance data collected by the ITR, constitutes one of the main objectives of the research activity, whatever is the application pursued. In fact, high resolution AM-LR systems have a great interest for their potentials in accurate 3D imaging of valuable objects which must be preserved in digital archives. Examples range from artwork monitoring, cataloguing and restoration from sparse fragments, to medicine for non-hazardous diagnostics and fast design of bio-compatible prostheses, to microtechnology in the miniaturization of macro-components (plastic prototypes, quality control). Several meaningful results of measurements executed in various important European archaeological sites, in particular Santa Maria Antiqua church situated in Fori Imperiali area in Rome and Costanza (Romania), involving 3D color mapped representation are also presented.

Non-contact displacement measurement is one of important topics to analyze materials strength and structural deformation. In addition to the industrial applications in mechanical engineering, some research works in such fields as medical and dental fields, life science, textile industry, and even in cosmetics industry require non-contact methods for their specified research areas. Here we propose that both displacement of surface points and profile of an objective are able to be captured by processing textured random pattern on the surface and projected fringe pattern onto the sample. A few potentiall applications to dental and cosmetics fields using our proposal are included.

When the spatial fringe analysis method as one of the technologies is employed in speckle method, the speckle interferometry is also improved to the high speed and high resolutive measurement method. However, there are some problems in the practical use. Generally, fringe scanning technologies are employed in speckle interferometry under restricted conditions. Another speckle pattern except these two speckle patterns before and after deformation is required in the case that the fringe scanning technology is introduced for the high precise measurement in the speckle interferometry. In this paper, the new technology that can measure the phase distribution of fringes by using only two speckle patterns before and after the deformation is proposed. In this method, a fringe image is divided into some regions which have some different characteristics mutually in Fourier domain. Consequently, each region is transformed to spatial domain by inverse Fourier transformation. Then, the fringe image is analyzed by Spatial Fringe Analysis Method in spatial domain. Because the phase map of the specklegram is analyzed by the mathematical characteristics of Fourier transformation in the new analysis method, the fringe analysis for not only monotone increase or decrease but also convex or concave information can be realized with artificial carrier information.

Temporal fringe pattern analysis is invaluable in transient phenomena studies but necessitates long processing times. Here, we describe a parallel computing strategy based on the single program multiple data (SPMD) model and hyper-threading processor technology to reduce the execution time. In a two-node cluster workstation configuration, we found that execution periods reduced by 1.6 times using four virtual processors. To allow even lower execution times with increasing number of processors, the time allocated for data transfer, data read, and waiting should be minimized. Parallel or super computing is found here to present a feasible approach to reduce execution times in temporal fringe pattern analysis.

Different polymeric materials are widely used in various technological and manufacturing processes and products for vibration isolation due to their properties to reduce the elastic waves magnitude. However, this property of polymers to efficiently damp elastic waves is valid for linear waves only. Nonlinear waves (for example, strain solitary waves) on the contrary can propagate in polymer waveguides, having proper characteristics, for long distances with very little loss of amplitude (we proved that in numerous experiments in waveguides made of polystyrene and PMMA). The phenomenon of existence and propagation for long distances of this new type of waves in polymer materials can be of considerable importance in engineering regarding to the potential generation of such waves in elastic constructions, that was not considered before in calculations of their strength, plasticity and damage threshold. On the other hand it allows to obtain quantitative data on nonlinear wave dissipation in these materials. We report our recent experiments on soliton propagation in waveguides made of polystyrene and PMMA, long enough to cause noticeable changes of wave shape and amplitude. Basing on these data we estimate dissipation decrements for nonlinear waves in these materials.

Metal components subjected to cyclic stress develop surface-evident defects (microcracks, slip bands, etc). Monitoring the formation and evolution of these fatigue damage precursors (FDPs) with increasing numbers of cycles can be an effective tool for determining the fatigue state of the component, which can be used in remaining fatigue life prognostics. In this paper a laser scanning technique for FDP detection is described and experimental results from examination of specimens of several metal types are presented. This technique is based on scanning a focused laser beam over the specimen surface and detecting variations in the characteristics of the scattered light signal. These variations can indicate the presence of surface abnormalities and therefore can be associated with fatigue damage formation. Particular patterns of spatial, angular, and optical characteristics can be used to identify and discriminate many types of FDP, which can provide a means to enhance the accuracy of surface defect frequency estimates and to eliminate the false counts that typically occur on surfaces in uncontrolled environments. Experiments during fatigue testing in the laboratory have shown that the technique can produce a defect frequency estimate that relates well to remaining fatigue life, but previous experiments showed large "plateau" regions, in which the slow defect frequency change made life estimation difficult. New data collection and analysis techniques have therefore been developed, and new experiments have been performed to test the ability of this modified approach to improve the utility of defect frequency measurements over the whole of fatigue life.

Resistance spot welding is now widely used in the fabrication of sheet metals, mainly due to the cost and time considerations. Friction stir spot welding is getting more and more acceptance in the automotive industries. Such spot welds are found in nearly all products where sheet metal is joined. Obviously the quality of the spot weld has a direct impact on the quality of the product. The most important quality target of spot welds is the size of the weld nuggets. If the weld nuggets are improperly or incompletely formed, or the area surrounding the nugget is smaller than required, the structural integrity of the entire part may be uncertain. Furthermore these inconsistencies are usually internal and are seldom visible to optical inspection. This study is focused on the quality analysis of the spot welds by using "Digital Shearography". The paper mainly focuses on developing a novel, whole field technique for non-destructive inspecting the size of spot-welds, both for the resistance spot weld and the friction stir spot weld.

Thermographic nondestructive inspection techniques have been shown to provide quantitative, large area damage detection capabilities for the ground inspection of the reinforced carbon-carbon (RCC) used for the wing leading edge of the Shuttle orbiter. The method is non-contacting and able to inspect large areas in a relatively short inspection time. Thermal nondestructive evaluation (NDE) inspections have been shown to be applicable for several applications to the Shuttle in preparation for return to flight, including for inspection of RCC panels during impact testing, and for between-flight orbiter inspections. The focus of this work is to expand the capabilities of the thermal NDE methodology to enable inspection by an astronaut during orbital conditions. The significant limitations of available resources, such as weight and power, and the impact of these limitations on the inspection technique are discussed, as well as the resultant impact on data analysis and processing algorithms. Of particular interest is the impact to the inspection technique resulting from the use of solar energy as a heat source, the effect on the measurements due to working in the vacuum of space, and the effect of changes in boundary conditions, such as radiation losses seen by the material, on the response of the RCC. The resultant effects on detectability limits are discussed.

In August 2003, NASA's In-Space Propulsion Program contracted with our team to develop a prototype on-board Optical Diagnostics System (ODS) for solar sail flight tests. The ODS is intended to monitor sail deployment as well as structural and thermal behavior, and to validate computational models for use in designing future solar sail missions. This paper focuses on the thermography aspects of the ODS. A thermal model was developed to predict local sail temperature variations as a function of sail tilt to the sun, billow depth, and spectral optical properties of front and back sail surfaces. Temperature variations as small as 0.5 ^oC can induce significant thermal strains that compare in magnitude to mechanical strains. These thermally induced strains may result in changes in shape and dynamics. The model also gave insight into the range and sensitivity required for in-flight thermal measurements and supported the development of an ABAQUS-coupled thermo-structural model. The paper also discusses three kinds of tests conducted to 1) determine the optical properties of candidate materials; 2) evaluate uncooled microbolometer-type infrared imagers; and 3) operate a prototype imager with the ODS baseline configuration. (Uncooled bolometers are less sensitive than cooled ones, but may be necessary because of restrictive ODS mass and power limits.) The team measured the spectral properties of several coated polymer samples at various angles of incidence. Two commercially available uncooled microbolometer imagers were compared, and it was found that reliable temperature measurements are feasible for both coated and uncoated sides of typical sail membrane materials.

Performance of an optoelectronic setup allowing heating of a remote engineering structure and subsequent analysis of the resulting deformation is described. The structure is heated by a CO₂ laser beam. This gives rise to a thermal stress in the heated region and to a global deformation of the structure. The latter cited is also illuminated by a HeNe laser beam. The light intensity distribution in the backscattered HeNe light wave is digitally recorded and processed by convenient software, which yields the structure deformation and allows the remote observer to get information about its thermal and mechanical properties. A typical application of the setup, consisting in remote damping of free vibrations of a cantilever bar, is presented.

Bone is a mechanosensitive tissue that adapts its mass, architecture and mechanical properties to mechanical loading. Appropriate mechanical loads provide an effective means to stimulate bone remodeling and prevent from bone loss. It is controversial whether in situ strain in bone is a critical determinant in enhancement of bone formation, and it is therefore important to evaluate load-driven strain in bone. Using electronic speckle pattern interferometry, we determined high-resolution three-dimensional strains on the mouse femur in response to two loading modalities: an axial loading modality (ALM) and a knee loading modality (KLM). We demonstrated that these two loading modalities induced a different pattern of strain distributions. ALM generated strain in the midshaft of cortical bone, while strains with KLM were concentrated on the distal epiphysis of the mouse femur. Since KLM is capable of enhancing bone formation in cortical bone distant from the knee, the current results indicate that in situ strain is not always necessary for load-driven bone formation.

By design, point-diffraction interferometers are much less sensitive to environmental disturbances than dual-path interferometers, but, until very recently, have not been capable of phase shifting. The liquid crystal point-diffraction interferometer (LCPDI) utilizes a dye-doped, liquid crystal (LC) electro-optical device that functions as both the point-diffraction source and the phase-shifting element, yielding a phase-shifting diagnostic device that is significantly more compact and robust while using fewer optical elements than conventional dual-path interferometers. These attributes make the LCPDI of special interest for diagnostic applications in the scientific, commercial, military, and industrial sectors, where vibration insensitivity, power requirements, size, weight, and cost are critical issues. Until very recently, LCPDI devices have used a plastic microsphere embedded in the LC fluid layer as the point-diffraction source. The process for fabricating microsphere-based LCPDI devices is low-yield, labor-intensive, and very "hands-on"; great care and skill are required to produce devices with adequate interference fringe contrast for diagnostic measurements. With the goal of evolving the LCPDI beyond the level of a laboratory prototype in mind, we have developed "second-generation" LCPDI devices in which the reference-diffracting elements are an integral part of the substrates by depositing a suitable optical material (vapor-deposited thin films or photoresist) directly onto the substrate surface. These "structured" substrates eliminate many of the assembly difficulties and performance limitations of current LCPDI devices as well as open the possibility of mass-producing LCPDI devices at low cost by the same processes used to manufacture commercial LC displays.

A new extensometer has been developed which needs no attachment of line markers or mechanical attachment on a specimen. An expanded beam from a laser diode is incident on the marker position of a specimen which is imaged by a lens on a C-MOS image sensor. The resultant laser-speckle patterns are analyzed by two-dimensional digital correlation at the rate of 20 frames per second. It provides speckle displacement by means of a phase-only-correlation device which uses only phase of Fourier transform of the image. In-plane displacement of the marker position is tracked by moving a head containing the laser and the image sensor under the feedback control that compensates for the speckle displacement detected. Two positions on the specimen are tracked by a pair of the heads. From rubber specimens which had a marker distance of 20 mm and were elongated at the velocity of 500 mm/sec we observed good agreement in load-strain curves with the results from the conventional methods using mechanical trackers.

The resolution of digital holography as an optical imaging system is described by the point spread function of the system. The point spread function of double aperture digital holography is determined. It promises the possibility of a resolution increase by the concept of synthetic apertures. First results of numerically reconstructed wave fields from synthetic digital holograms combined of two single holograms are shown. Furthermore an experimental method for the exact determination of the mutual CCD position and orientation is presented.

Digital image correlation is used for the deflection measurement of a simple beam model in this study. The deflection distributions are obtained from images that are recorded using a digital camera with a shift lens. The experimental results show that the use of a shift lens is effective for the case of situations where direct view of the object is obscured. In addition, it is found that the deflection distribution of the relatively large structures can be measured using digital image correlation even if the random pattern is not painted on the object surface. The deflection measurement of bridges using digital image correlation for safety inspection is expected in the near future.

Low coherence optical interferometry has been proven to be an effective tool for characterization of thin and ultra-thin, transparent and non-transparent semiconductor Si and compound wafers, and MEMs structures for ex-situ and in-situ applications. We demonstrate that use of synchronously operating probes significantly reduces vibration noise observed in the system. We demonstrate that application of synchronized improves reproducibility of measurement with standard (without vibration insulation) 20 Hz acquisition rate low coherence dual probe interferometer from 1.5 um down to below 0.5 micrometer under vibration conditions of modern semiconductor manufacturing facilities. The synchronous configuration also results in reduction of the cost of the multi-probe system by employing one motion stage rather than several independently controlled stages. Finally we discuss recent progress in high-speed measurements allowing as to increase acquisition rate to >10 kHz (acquisition time shorter than 0.07 msec), while maintaining accuracy and reproducibility of standard slower system.

Controlling/monitoring the thickness of applied paint in real time is important to many situations including painting ship and submarine hulls in dry docks for maintaining health of ships and submarines against the harshness of the sea, in automobile and aerospace industries, and in a variety of other industries as a control sensor that plays significant role in product quality, process control, and cost control. Insufficient thickness results to inadequate protection while overspray leads to waste and pollution of the environment. A rugged instrumentation for the real time non-contact accurate measurement of wet and dry paint film thickness measurement will be immensely valuable. As paint is applied with several layers of the same or different type, thickness of each newly sprayed wet layer is of most interest, but measurement on dry paint is also useful. In this study, we use acousto-optic tunable filter-based near infrared spectrometer to obtain the absorption spectrum of layers of paint sprayed on sand blasted steel surface and thus measure the thickness of coating under both wet and dry situations. NIR spectra are obtained from 1100 to 2300 nm on four sample of different thickness of paint up to 127 micron. Partial least squares model built with the spectra shows good correlation with standard error of prediction within ~ 0.7 micron. Results indicate that the spectra also respond to the amount of organic solvent in the wet paint and can be used to monitor the degree of dryness of the paint in real time.

This paper describes the development of spectrum computation and analysis for a single model and untunable laser spectroscopy to detect the species concentration and space distribution in pre-combustion gases. Absorption spectroscopy using infrared laser diode provides a dynamic, non-instructive, and in situ way to determine the concentration and distribution of the mixture of fuel gas and O₂ in the pre-combustion gas stream. For species, wavelength suitable for absorption spectroscopy is determined using the spectra distributions of the species provided in HITRAN database. Inverse method and Abel algorithm are employed separately to retrieve the concentration of species and calculate the distribution of the measured gas. The results of the paper provide the foundation to develop a dynamic diagnostic instrument to monitor the state of gaseous species in hostile environments such as various industrial combustion systems.

A novel technique for measurement of high frequency temperature fluctuations in unseeded gas flows using molecular Rayleigh scattering is investigated. The spectrum of laser light scattered from molecules in a gas flow is resolved using a Fabry-Perot interferometer. The width of the spectral peak is broadened by thermal motion of the molecules and hence is related to gas temperature. The interference fringe pattern containing spectral information is divided into four concentric regions using a series of mirrors angled with respect to one another. Light from each of these regions is directed towards photomultiplier tubes and sampled at 10 kHz using photon counting electronics. Monitoring the relative change in intensity within each region allows measurement of gas temperature. Independently monitoring the total scattered intensity provides a measure of gas density. This technique also has the potential to simultaneously measure a single component of flow velocity by monitoring the spectral peak location. Measurements of gas temperature and density are demonstrated using a low speed heated air jet surrounded by an unheated air co-flow. Mean values of temperature and density are shown for radial scans across the jet flow at a fixed axial distance from the jet exit plane. Power spectra of temperature and density fluctuations at several locations in the jet are also shown. The instantaneous measurements have fairly high uncertainty; however, long data records provide highly accurate statistically quantities, which include power spectra. Mean temperatures are compared with thermocouple measurements as well as the temperatures derived from independent density measurements. The accuracy for mean temperature measurements was +/- 7 K.

Hydrogen flame, which emits only in the ultraviolet and infrared regions and is therefore invisible, was visualized by imaging at 309 nm, which corresponds to the peak in the OH emission. The background was imaged simultaneously at 337 nm, where the flame emission is very weak. Both images were obtained using narrowband interference filters of 1.5 nm bandwidth and image intensifiers, and the flame image was extracted from the difference in the intensity of the images at the two wavelengths. A combination of (1) digitization using a threshold intensity level and (2) Gaussian blur were applied to the difference image for rejection of spurious spots which resulted from the grainy appearance of the image obtained by the image intensifier. This method allowed elimination of reflected sunlight. The method was also used to image hydrogen flame using interference filters of 10 nm bandwidth. The flame region was successfully extracted up to a working distance of 30 m under outdoor daylight conditions.

Various kinds of optical diagnosis for atmospheric pressure non-thermal plasma which the authors have examined experimentally, are explained. They are LIF of OH (248nm excitation), NO (226nm), TARIF of O (225nm), Sclieren image, ozone profile observation by the laser absorption, spectrum analysis of the plasma including NO-γ emission, and streamer propagation. The last can be controlled by the gated IICCD camera but others are controlled by the laser emission which makes possible to observe the time change after the plasma. Those data propose the O generation in the streamer region which produces the ozone or VOCs oxidation. O radical is now a very important parameter as the VOCs decomposition, especially, related with the catalyst effect.

Concentration distributions of formaldehyde were measured in a technical fuel mixing system by Planar Laser Induced Fluorescence (PLIF) using a novel all solid state disk laser system. This compact and efficient laser generates tunable, narrow bandwidth pulses with kHz repetition rate and energies of up to 25 mJ around 1030 nm. After frequency conversion to the UV spectral region, laser pulses with energies of up to 4 mJ excite different combustion relevant species inside of a semi-technical reactor. This reactor generates a homogeneous fuel vapor/air-mixture using the so-called cool flame. Since the mixture of fuel and air is a key factor concerning efficiency of combustion, the fast fuel injection and mixing processes were investigated with this laser system. Directing a light sheet into the reactor and collecting the fluorescence with an intensified CCD camera, we recorded PLIF images of formaldehyde concentration distributions using an excitation wavelength of 343 nm. In this way we characterized the turbulence of the injection process close to the fuel injection nozzle with 1 kHz repetition rate, and proved the excellent homogeneity of the fuel-air mixture close to the end of the reactor, where fuel-air mixture was burned in a hot flame. By means of scattered light from fuel droplets the mean flow velocity could be estimated. In the hot flame above the reactor spectrally resolved LIF of OH radicals could be recorded.

Cavity ringdown specectroscopy (CRDS) methods have become widely used for trace gas concentration measurements as an enhanced absorption spectroscopy method. We have applied CDRS to a sample cell and simulated particulate soot to develop a CDRS system that will allow rapid measurement of soot absorption and hence density in raw diesel engine exhaust. Results will be shown from several similar systems illustrating the range of improvements available from system optimization. A final system will be shown that appears to be reasonably successful in terms of sensitivity, but is at present not able to provide reliable single-shot measurements. Illustrations of future modifications we plan to develop the single-shot capability will be shown.

In this paper UV-visible elastic light scattering and Planar Laser Induced Fluorescence (PLIF) have been applied for measuring the vaporization process of a diesel fuel in an optically accessible vessel at engine ambient conditions. The spray has been generated by an electronically controlled Common Rail injection system and emerged from an axial single-hole electroinjector, 0.18 mm in diameter (L/d = 5.55). The injected fluid has been a commercial Diesel fuel and a single strategy (1.0 ms in duration) has been implemented at the injection pressure of 60.0 MPa. The measurements have been carried out in a quiescent bomb filled with SF₆ gas at pressures of 0.39 MPa and temperature ranging between 293 to 533 K. The ambient gas densities has varied from 12.64 kg/m³ to 23.0 kg/m³, equivalent to the diesel engine conditions between the Start of Injection (SOI) and the Start of Combustion (SOC). A Nd-YAG pulsed laser sheet has been used for excitation of the spray along its axis at two wavelengths: 532 and 355 nm; the sheet thickness and light pulse duration have been 0.10 mm and 12 ns, respectively. The scattered light has been collected and synchronized at different instant from the SOI. The comparison of the images of the fuel at different instant from the SOI has permitted the analysis of the spray characteristics in terms of tip penetration, cone angle and spray fragmentation. Elastic visible and UV scattering radiation have allowed investigations on the size of the droplets along a plane centered on the spray axis. Planar Laser Induced Fluorescence (PLIF) measurements on the same plane have been carried out exciting the droplets at 355 nm and collecting the light through an interference filter centered at 430 nm. PLIF has allowed a correlation between the liquid and the vapor structures of the jets in all the examined ambient conditions.

Two passive optical techniques are described to investigate combustion. Optical Emission Tomography (OET) is used for non-intrusive study of heat release through the detection of chemiluminescence by the hydroxyl radical that is generated in the burning process. The OET technique described here is based on a passive fibre-optic detection system, which allows spatially resolved high-frequency detection of the flame front in a combustion flame, where all fibres detect the emission signals simultaneously. The system withstands the high pressures and temperatures typically encountered in the harsh environments of gas turbine combustors and IC engines. The sensor-array is non-intrusive, low-cost, compact, simple to configure and can be quickly set up around a combustion field. The maximum acquisition rate is 2 kHz. This allows spatially resolved study of the fast phenomena in combustion. Furthermore, the production of NOx is investigated through the emission of green light as a result of adding tri-methyl-borate to a flame. In combustion, the tri-methyl-borate produces green luminescence in locations where NOx would be produced. Combining the green luminescence visualisation with OET detection of the hydroxyl radical allows monitoring of heat release and of NOx production areas, thus giving a means of studying both the burning process and the resulting NOx pollution.

Coatings can be classified by either their appearance, such as glitter, or by their function, such as corrosion protection. However, pigments are currently being manufactured with new and unique appearance attributes that can not be characterized by traditional methods. These coatings may exhibit differences in their perceived color with changes in the illumination or viewing angle, or both. Properties such as these have become rudimentary in the production of currency, cosmetics, and retroreflective materials. The primary impetus of goniospectrometry at NIST is to develop accurate measurement protocols for reproduction and quality control of appearance attributes, such as color matching, by determining the minimum set of illumination and viewing geometries needed to accurately characterize the perceived color. Here, we present a new goniospectrometer developed at NIST that allows the measurement of the complete bi-directional reflectance distribution function (BRDF) for colored surfaces with the objective of differentiating between the scattering mechanisms in the coating. The illumination is provided by a monochromator with a spectral resolution of 0.05 nm between 360 nm and 780 nm. The sample can be moved about 3 different axes, allowing illumination and viewing for any direction within the hemisphere about the sample, including grazing angles, with accuracy better than 0.01° for each axis. This equipment will become the future provider of standard BRDF measurements at NIST, for the characterization of complex surfaces like gonioapparent coatings or retroflective surfaces.

The United Kingdom scales for diffuse reflectance are realized using two primary instruments. In the 360 nm to 2.5 μm spectral region the National Reference Reflectometer (NRR) realizes absolute measurement of reflectance and radiance factor by goniometric measurements. Hemispherical reflectance scales are obtained through the spatial integration of these goniometric measurements. In the mid-infrared region (2.5 μm - 55 μm) the hemispherical reflectance scale is realized by the Absolute Hemispherical Reflectometer (AHR). This paper describes some of the uncertainties resulting from errors in aligning the NRR and non-ideality in sample topography, together with its use to carry out measurements in the 1 - 1.6 μm region. The AHR has previously been used with grating spectrometers, and has now been coupled to a Fourier transform spectrometer.

In technical heat treatment processes - e.g. the sintering process - the kiln as well as the heat treated material need to have a fairly homogeneous temperature distribution. In the kiln the heat is transferred from the furnace walls to the kiln aids and from the aids to the heat treated material. An example for such processes is the sintering of ceramics, where the heat is transferred from sintering aids to the sintering ceramic material. To guarantee an optimized heat treatment the details of the heat transfer need to be known. Many heat treatment procedures operate at such high temperatures that heat transfer is mainly dominated by radiation, but the emissivities of typical refractory materials of kiln and sintering aids in general are hardly known. Therefore, the spectral emissivities of some typical kiln materials and sintering aids were measured in the temperature range from 200 to 1200°C and in the spectral range from 0.8 to 25 μm at the radiation measurement device of the University Duisburg-Essen. These data were used to compute the temperature-dependent total emissivities. The paper describes the equipment for radiation measurement, the measured temperature-dependent spectral emissivities as well as the computed temperature-dependent total emissivities. It was found out, that different materials have different temperature-dependent spectral and total emissivities which may significantly influence the heat transfer in high temperature processes.

A huge number of optical spectra have been measured in the ultraviolet, violet, visible, infrared and far-infrared regions. However transmittance and reflectance can only be measured by the use of a spectrometer, it is very difficult to measure the transmittance and reflectance with the same accuracy. Our STAR GEM (Scatter, Transmission and Absolute Reflection using a Geminated Ellipsoid Mirror) is the first realization not only to overcome the difficulty but also to make the absolute measurements of transmittance and reflectance at any incident angle. The STAR GEM is a new optical accessory and is designed so that it can be incorporated into commercial Fourier-transform infrared spectrometers. Although the STAR GEM is used for infrared spectral measurements, the measurement methods, design principles, and features are generally applicable to other wavelengths as well.

Emulsions of heavy oils in water are prepared to allow transportation of highly viscous oils over long distances. Their stability is currently assured by addition of surfactants, which cover the suspended oil particles with an electrically charged protective layer. The oil refractive index, which is related to the oil electrical properties, is therefore an important parameter in emulsion stability theory. In addition, as oils extracted from different wells have different refractive index, knowledge of the latter helps to identify oil samples. Basic principles and operation of an optoelectronic setup allowing real-time measurement of the real part of the refractive index (n) of heavy oil samples as a function of temperature (T) in a wide temperature range are presented. The setup consists of a CW laser beam which locally heats the oil sample (so inducing a time-growing temperature gradient and local deformation of the liquid surface) and an optoelectronic system which records as a function of heating time (t) the time-varying divergences of light beams reflected by and transmitted through the sample. As the latter cited are mathematically related to the refractive index value, function n(t) is thus experimentally determined. The sample temperature (T) is simultaneously recorded as a function of heating time (t) by means of a thermographic camera, thus obtaining function T(t). Combining both plots [n(t),T(t)] the function n(T) is determined in a few minutes in the whole temperature range.

In PIV particle image blur is usually observed near fluid optical interfaces, i.e. shock waves, and thin flow structure with large density variations, e.g. shear layers and boundary layers. In such an environment the particle image is not only subject to blur, but is also displaced from its actual position due to refraction, which is denoted as optical displacement. In this study particle image blur near a shock wave is investigated in relation to the auto- and cross-correlation map, measurement accuracy and confidence level. The results from a numerical study are supported by PIV measurements of a shock wave in a supersonic wind tunnel. It is demonstrated that particle images are blurred in the direction of lower refractive index (directional blurring). The particle images are also skewed. Therefore particle image blur not only causes correlation peak broadening due to the fact that the particle images increase in size, but more importantly can introduce an asymmetry in the correlation peak and in turn introduce a small bias error in the measured velocity. However, experimental results indicate that particle image blur itself is not the main cause for the increase in measurement uncertainty near shock waves, but that the reduced accuracy can be attributed to the optical displacement. The observation of particle image blur can be used as a detection criterion for a qualitative assessment of the optical displacement. Certain combinations of experimental parameters (viewing angle, f/# and interrogation window size) yield significant errors in the measured velocity. Under certain circumstances optical distortion can become so strong to introduce an unphysical acceleration within the shock wave, visualized as an inflection point with positive slope in the velocity profile across the shock. The study provides some practical suggestions to limit the effect of aero-optical distortion on the velocity measurement.

The work presented here describes a method that allows three component velocity measurements to be made, quickly and non-intrusively, across a plane in a flow defined by a laser light sheet. The method, two frequency planar Doppler Velocimetry (2ν-PDV) is a modification of the Planar Doppler Velocimetry (PDV) technique, using only a single CCD camera, and sequential illumination of the flow using two frequencies, separated by about 700MHz. One illumination frequency lies on an absorption line of gaseous iodine, and the other just off the absorption line. The beams sequentially illuminate a plane within a seeded flow and Doppler-shifted scattered light passes through an iodine vapour cell onto the camera. The beam at a frequency off the absorption line is not affected by passage through the cell, and provides a reference image. The other beam encodes the velocity information as a variation in transmission dependent upon the Doppler shift. Use of a single camera ensures registration of the reference and signal images, which is the major problem in any spilt image system such as a two-camera imaging head, and cost efficiency is improved by the simplification of the system. A 2ν-PDV system was constructed using a continuous-wave Argon ion laser and acousto-optic modulators to produce two frequencies of illuminating laser light. This was combined with multiple imaging fibre bundles, to port three different views of the measurement plane to a CCD camera, allowing the measurement of three velocity components.

One of the visual problems hardest to recognize in liquid crystal displays (LCDs) is an area of non-uniform brightness called a mura. The accurate and consistent detection of a low-contrast mura is extremely difficult because the boundary between the regional mura and the background is indistinct. This paper presents a novel method for detection and quantitative measurement of low-contrast mura. Compared with some wavelet approaches, the multiple resolution analysis method based on the Symmetric Selesnick multiwavelet has advantages for practical use.

We have developed 3D-Measuring-Modelling System, which can be applied to any object from small to large size, using a note PC and digital cameras. This time, especially in view of its application to the area of industrial measurement, we have endeavored to attain higher accuracy in 3D measurement (from former 0.26mm to present below 0.1mm) as well as the further simplification of the measuring operation. For this purpose we have developed a scale bar and other peripheral devices and we assessed the resulted accuracy. Therefore, today we should like to report on the new system thus developed and its accuracy assessment, as well as its various application examples in automobile measurement.

A friction induced impulse noise of a plasma display panel (PDP) TV caused by a stick-slip phenomenon can be characterized as a single pulse sound or a burst sound with a duration time between 0.001 and 1 second, which can be occurred in all of constrained places such as screwed points or touching surfaces of two panels due to sudden temperature changes of a product. It is desired to find the source of noise in order to reduce magnitude and frequency, however, it is very difficult thing because of unexpected occurrence and short duration. This paper shows the technique to detect the source of a noise by using the Double Pulse Electronic Speckle Pattern Interferometry (ESPI) and the Laser Doppler Vibrometer (LDV). The double pulse ESPI can be well applied for a measurement of a dynamic deformation because it is able to catch a source of noise by observing the deformation field of a part caused by instantaneous slip in an instant of a emission of accumulated thermal energy in screwed points and touching surfaces. For a measurement of a microscopic deformation by a frictional surface slip occurred in a short duration within 100us, spatial phase shift method which works well for high speed application such as a deformation by a shock was used in double pulse ESPI. The firing signal of pulse ESPI can be received by triggering the impulse magnitude at a moment of a slip. Pulse ESPI can catch the deformation by a minute slip at a moment of noise, which contributed greatly to reduction of frictional noises in PDP TV.

We have obtained analytical formulas for the phase difference in case of two-beam interferometry of symmetrical flow with inner shocks. These formulas were analyzed for transparent media having axial, central and cylindrical symmetry. They were used to digitally synthesize the interferometric pictures in density distribution simulations. It is of interest to study the interferometric fringes behavior in the areas near the inner shocks. It is proposed to use simple models for the density field simulation so results of the calculations can be compared with the experimental interferometric results. Using simulated density fields and digital interferometry, we have numerically created interferograms utilizing some of the continuous field techniques developed by authors early. The comparison of the experimental interferometric pictures with the calculated pictures shows the possibility to use the developed technology to study flow fields with the inner shocks. The results of comparison are illustrated by examples of such interferometric pictures.

Providing fluorescence and fluorescence excitation spectra traceable to the scale of spectral sensitivity (responsivity) and spectral radiance at minimized uncertainty is currently limited by two factors: The uncertainty of the available transfer standards and the uncertainty of the measurement process itself. Here the requirements on a reference fluorometer enabling measurements at minimized uncertainty, its design, the simulation and the realization are presented. The fluorometer is designed with minimized chromatic and geometrical aberrations. To realize an efficient reduction of stray light and subtractive dispersion a double monochromator design was necessary. The basic element is a so-called U-type Czerny-Turner single monochromator featuring off-axis parabolas and an entrance and exit slit virtually at the same place. Thereby spherical aberration, coma and astigmatism are effectively minimized. The here employed special double monochromator design further cancels the remaining aberrations of the single monochromator. The design of the whole spectrometer was optimized with a ray tracing program. To minimize uncertainties due to the transfer standards, the reference fluorometer is exclusively traceable to the spectral sensitivity (responsivity) scale. This enables the use of transfer standards with much smaller uncertainty. Here trap detectors are employed of common design but specially calibrated for a divergent light bundle. Based on this instrument with its achromatic design and precisely known numerical apertures the determination of absolute fluorescence spectra will be addressed.