The return of the Long Duration Exposure Facility (LDEF) in 1990 brought a wealth of space exposure data on materials, paints, solar cells, etc. and data on the many space environments. The effects of the harsh space environments can provide damaging or even disabling effects on spacecraft, its materials, and its instruments. In partnership with industry, academia, and other government agencies, National Aeronautics & Space Administration's (NASA's) Space Environments & Effects (SEE) Program defines the space environments and provides technology development to accommodate or mitigate these harmful environments on the spacecraft. This program provides a very comprehensive and focused approach to understanding the space environment, to define the best techniques for both flight and ground-based experimentation, to update the models which predict both the environments and the environmental effects on spacecraft, and finally to ensure that this information is properly maintained and inserted into spacecraft design programs. This paper will describe the current SEE Program and will present SEE contamination engineering technology development and risk mitigation for future spacecraft design.

This paper describes a program for consolidating data from quartz crystal microbalances (QCMs) that will enable one to rapidly locate previous measurements on specific materials and data from past space flight experiments. When complete, the databases will contain information on materials outgassing obtained using the ASTM-E-1559 standard, and flight observations of mass accumulations. Once established, these databases will be available to the entire community and will provide a valuable source of material outgassing information. The data should be useful to those working in the Contamination area for mission design and materials specification. Data are being accumulated from both national and international sources. The space flight database will include data from past NASA missions, as well as DOD [including the BMDO-sponsored Mid-course Space Experiment (MSX) program], Canadian Space Agency, European Space Agency, Russian MIR space station, and eventually, the International Space Station. A website is being generated which will be the vehicle for storing the data that are accumulated. Once completed, the databases will be managed by the NASA/Space and Environmental Effects (SEE) Program Office at the Marshall Space Flight Center in Huntsville, Alabama.

Contaminants degrade the thermal properties of spacecraft systems. This paper describes a method of quantified visual inspection, which assumes a minimum visible particle size that can be easily evaluated for any observer. It also assumes a log-normal particle size distribution, but not the slope of it. By counting the particles visible in a convenient unit area, the fractional area coverage can be calculated. The method can be applied to real systems during ground inspection. This paper discusses methods for assessing the radiant cooler sunshields of the Imager and Sounder instruments on the Geostationary Operational Environmental Satellite (GOES) spacecraft. Then the method for converting the percent area coverage to the amount of solar power, which is scattered, to the cooler patch is explained. The essence of this conversion is based on careful consideration of the paths of specularly reflected and scattered solar light within the sunshield enclosure. A three-dimensional Bidirectional Reflectance Distribution Function (BRDF) model of the radiant cooler sunshield was constructed in order to estimate the illumination of a contaminated spot on a sunshield wall based on relative sun orientation, direct illumination, and specularly-reflected illumination from other walls. Radiant energy reflected from the contaminated spot to the radiant cooler was estimated using a BRDF model based on data reported by Young in previous studies.

General sticking coefficient models have been developed at LMMS for both unexcited molecules (no photochemical reaction effects) and photochemically excited molecules in a solar vacuum ultraviolet radiation environment. This paper describes applications of these models to spacecraft on-orbit contamination analysis. The first (non-photochemical) model was used for evaluation of internal contamination problem for an Earth-viewing instrument. The model examined potential molecular contamination to an instrument mirror from Chemglaze Z306 paint outgassing during the orbital flight. The model was correlated with available Chemglaze Z306 outgassing test data at a source temperature of 75 degrees Celsius and was then used to predict mirror deposition buildup under a relatively low source temperature of 30 degrees Celsius during 5-year mission flight. The second (photochemical) model correlated with measured photochemical contaminant deposition rates was used for examination of solar absorptance degradation of OSR (Optical Solar Reflector) radiators on a geosynchronous spacecraft in orbit for 10 years. The predicted degradation due to the photochemical reactions induced by solar vacuum ultraviolet radiation on spacecraft contaminants agrees well with flight data.

Contaminants form an instrument's self-generated sources or from sources external to the instrument may degrade its critical surfaces and/or create an environment which limits the instrument's intended performance. Analyses have been carried out on a method to investigate the required purging flow of clean, dry gas to prevent the ingestion of external contaminants into the instrument container volume. The pressure to be maintained and the required flow are examined in terms of their effectiveness in preventing gaseous and particulate contaminant ingestion and abatement of self- generated contaminants in the volume. The required venting area or the existing volume venting area is correlated to the volume to be purged, the allowable pressure differential across the volume, the external contaminant partial pressure, and the sizes of the ambient particulates. The diffusion of external water vapor into the volume while it was being purged was experimentally obtained in terms of an infiltration time constant. That data and the acceptable fraction of the outside pressure into the volume indicate the required flow of purge gas expressed in terms of volume change per unit time. The exclusion of particulates is based on the incoming velocity of the particles and the exit flow speed and density of the purge gas. The purging flow pressures needed to maintain the required flows through the vent passages are indicated. The purge gas must prevent or limit the entrance of the external contaminants to the critical locations of the instrument. It should also prevent self-contamination from surfaces, reduce material outgassing, and sweep out the outgassed products. Systems and facilities that can benefit from purging may be optical equipment, clinical facilities, manufacturing facilities, clean rooms, and other systems requiring clean environments.

Cleaning by spraying with an inert liquid (such as a hydrofluorocarbon or hydrofluoroether) is shown to be an effective means of removing contaminating particles from the surfaces of objects. This type of cleaning has resulted in surface cleanliness levels of better than class 200. It was also determined that liquid spraying with these fluids provides a suitable replacement for CFC-113 as a cleaning medium. A variety of substrates, including silicon wafers, coated gold and aluminum coated mirrors, and zinc sulfide windows for FTIR (Fourier Transform Infra Red) spectroscopy test cells were spray cleaned to assess materials compatibility. None of these surfaces showed any apparent deleterious effects from spraying.

The exposure of silicones to atomic oxygen in low Earth orbit causes oxidation of the surface, resulting in conversion of silicone to silica. This chemical conversion increases the elastic modulus of the surface and initiates the development of a tensile strain. Ultimately, with sufficient exposure, tensile strain leads to cracking of the surface enabling the underlying unexposed silicone to be converted to silica resulting in additional depth and extent of cracking. The use of silicone coatings for the protection of materials from atomic oxygen attack is limited because of the eventual exposure of underlying unprotected polymeric material due to deep tensile stress cracking of the oxidized silicone. The use of moderate to high volatility silicones in low Earth orbit has resulted in a silicone contamination arrival at surfaces which are simultaneously being bombarded with atomic oxygen, thus leading to conversion of the silicone contaminant to silica. As a result of these processes, a gradual accumulation of contamination occurs leading to deposits which at times have been up to several microns thick (as in the case of a Mir solar array after 10 years in space). The contamination species typically consists of silicon, oxygen and carbon, which in the synergistic environment of atomic oxygen and UV radiation leads to increased solar absorptance and reduced solar transmittance. A comparison of the results of atomic oxygen interaction with silicones and silicone contamination will be presented based on the LDEF, EOIM-III, Offeq-3 spacecraft and Mir solar array in-space results. The design of a contamination pin-hole camera space experiment which uses atomic oxygen to produce an image of the sources of silicone contamination will also be presented.

Long term stability of new and modified spacecraft materials when exposed to the space environment continues to be a major area of investigation. The natural and induced environment surrounding a spacecraft can decrease material performance and limit useful lifetimes. Materials must be thoroughly tested prior to critical applications. The Optical Properties Monitor (OPM) experiment provides the capability to perform the important flight testing of materials and was flown on the Russian Mir Station to study the long term effects of the natural and induced space environment on materials. The core of the OPM in-flight analysis was three independent optical instruments. These instruments included an integrating sphere spectral reflectometer, vacuum ultraviolet spectrometer, and a Total Integrated Scatter instrument. The OPM also monitored selected components of the environment including the molecular contamination. The OPM was exposed on the exterior of the Mir Docking Module for approximately 8-1/2 months. In flight OPM data measured a low, but significant, level of contamination compared to findings on other experiments deployed on Mir. Degradation of some materials was greater than expected including aluminum conversion coatings and Beta Cloth. Also, significant particulate contamination was detected on the TIS instrument from the return trip from Mir to the ground laboratory.

The QCPM has been developed to monitor particulate contamination in a space environment. The QCPM is similar in design to a TQCM in that it uses a thermoelectric device to control temperature and In Line Doublet Crystals to maintain frequency stability under solar radiation. The QCPM is coated with a thin layer of a vacuum fluid having a very low vapor pressure. At 0 degrees Celsius, the fluid is in a viscous liquid state and particles that fall onto the QCPM stick to its surface. Periodically, the particles are weighed by cooling the QCPM to -60 degrees Celsius to solidify the fluid and couple the particulates to the oscillator mass of the crystal. The results from a Scanning Electron Microscope and the Energy Dispersions Analysis by X-ray are presented showing the size, shape and composition of particles that contaminated surfaces flown on the Spacelab 1 Mission. Aluminum particles occurred in the greatest numbers and had diameters ranging between 0.5 to 10 micrometer.

Quartz crystal microbalances (QCM) have been used for over twenty years as contamination monitors in space satellites to measure film deposition on sensitive surfaces such optical mirrors, thermal radiators and solar arrays. However, it is only recently that miniature quartz crystal microbalances were used as particle monitors after the QCMs were coated with low outgassing grease to trap and measure the mass of particles impinging on the quartz surfaces. Results of these experiments utilizing 'sticky' QCMs are described for a series of wind- tunnel missile tests.

When used on a spacecraft to measure outgassing/erosion rates, a 50 MHz QCM is twenty-five times more sensitive than a 10 MHz QCM, according to theoretical considerations. In a continuation of extending the sensitivity of the QCMs, the frequency range, which is a measurement of mass flux, has increased from 15 MHz to 25 MHz to a now reported 50 MHz crystal sensor. As reported in the previous investigation of the 25 MHz crystal by Wallace, et. al., we again used a thin film interference technique to determine the mass sensitivity of the crystal. Water ice was used as the deposition film and, from known density, interference properties of the resulting film gave the resulting film thickness. Thus the sensitivity of the crystal and also the mass range of operation, with the driving electronics, could be determined. Theoretical sensitivity of the 50 MHz crystal would be 5.657 X 10⁹ Hz/g/cm² or 0.176 ng/cm²-Hz.

This paper concerns the light-absorptive black-chromium (BC) coating intended for reduction of stray light in the satellite-borne optical instruments and particle-analyzing apparatus operating in open space under intensive solar UV illumination. Resolution of this problem is also important in connection with development of the extra-atmospheric Far UV astronomy. The total hemispherical reflectance (THR) measurements of the BC coating samples were carried out at a wavelength of 121.6 nm -- the most intensive line in the short-wave part of the solar UV spectrum which creates the main contribution to the background noise of detectors in space apparatus. THR of the samples tested at a wavelength of 121.6 nm was as low as 2%. The samples of the BC coating were subjected to standard mechanical and environmental tests simulating the shipping, storage, launching, flight, and operating conditions of the space equipment. THR measurements of the samples were made following exposure to each test. As a result of mechanical and environmental testing the following features of the BC coating were discovered: (1) the coating stands up well to all types of mechanical effects (vibratory loads, linear overloads, and impacts) to which the space equipment may be subjected both when shipping to the space- vehicle launching site and also when launching; (2) the most undesirable effect for the undamaged surface of the coating is humidity -- this causes an increase of reflectivity with a factor of 1.2 on average; (3) the most dangerous outcome for the BC coating is the effect of rubbing -- the reflectivity is increased about two times at the place of contact. Advantages of the BC coating consists in its low reflectivity both in the vacuum UV and within the visible ranges, as well as in the short-wave infrared range. The BC coatings is also assumed to possess following valuable attributes: (1) at grazing incidence its reflectivity might be less than that of other types of coatings; (2) low fraction of the incident radiation reflected into the specular peak relative to the THR.

A major problem of in-situ surface characterization by using angle-resolved light scattering is the fast and accurate surface parameter identification. This paper will deal with surface parameter identification methods from BRDF measurements of rough surfaces with stochastical height topographies. First, neural classification methods will be discussed. Second, the discussed classification method will be applied to BRDF data taken by an ARS silicon sensor with 8013 polar photodiodes. The classification results will be compared to topography data taken from AFM measurements. Finally, neural self-organized networks will be applied to classify in unsupervised manner rough surfaces based on BRDF measurements.

This article describes briefly the optical surface profileometry in China, including several result of its theory research, optical profiler development and some problems using the optical profiler.

The statistical properties of speckle patterns that are generated in the Fresnel region, when a rough surface is illuminated with a fully developed static speckle pattern are studied. The intensity autocorrelation function characterizes the roughness of specularly reflecting surfaces. The measuring effect is based on a roughness-dependent spatial intensity modulation of the speckle field which is scattered from a surface under speckle pattern illumination. In addition, anisotropic surfaces give rise to an anisotropy of the speckle modulation phenomenon. The speckle patterns under investigation are first recorded by use of a CCD camera and are then evaluated by digital image processing in order to determine a 2D-autocorrelation function. The main advantage of this approach compared to profilometric and light scattering methods such as angle resolved scattering (ARS) and total integrated scattering (TIS) is its reliability and its capability to in-process applications. The measurement results basically depend on the rms roughness. In comparison with ARS- based measuring principles, the surface autocorrelation length shows only little influence. Furthermore, only a small angular range (less than 5 deg.) of the scattered light distribution needs to be evaluated, so that distances of more than 100 mm between optical setup and rough surface can be realized. Earlier investigations in this field deal with speckle patterns obtained from transmitting isotropic surfaces. In this study reflecting anisotropic surfaces, which are typically produced by mechanical processes such as grinding and turning are taken into consideration. Therefore, a more general theoretical description of the rough surface which covers both, isotropic and anisotropic roughness will be given.

To measure microroughness, defects and contamination on surfaces such as wafers or optical instruments stray light sensors are a fast means. In order to obtain a traceable quantitative, i.e. metrological, measure of roughness (rms) the relation between rms from BRDF of a stray light sensor and rms from topography has to be given. The quantification of stray light sensor signals can well be done with smooth surfaces that have no defects, since forward simulation of the bidirectional reflectance distribution function (BRDF) from smooth surfaces obeying Rayleigh-Rice approximation is possible. We have measured the topography of large areas up to 315 X 315 micrometer² with an atomic force microscope (AFM) by patching several scans (up to 25) with overlap to obtain bandwidth limits compatible to our stray light sensor. In profilometry roughness usually is evaluated after detrending, i.e. subtraction of surface figures. Hence for an evaluation of the roughness parameter rms by integrating the BRDF of a stray light measurement, the integration limits need to be chosen carefully. This paper gives a detailed discussion on a quantification of roughness measures.

As every branch of industry the cosmetic industry has to control the quality of its products and to prove the assured treatment effects. Therefore, the structure of human skin is measured by mechanical or optical devices and the measurement data have to be analyzed. Until today, the devices commonly used in the industry only allow to measure profiles of replicas of the human skin and the methods of data analysis are classical methods e.g. digital filtering or Fourier Transform (FT). Recently, one can also find new methods such as in-vivo measurement of human skin with systems using active image triangulation or the Wavelet Transform for analysis and filtering of the raw measurement data. This paper discusses the qualifications of these new methods of measurement and data analysis in comparison to the classical ones.

This paper presents a system for three-dimensional topography measurement, of both smooth and rough surface, based on triangular beam scanning technique. This system utilizes a simple but efficient principle based on the general principle of light-section method and the idea of light scanning technique to acquire topography. Its ability of anti- interference is powerful and it can be used at locale of manufacturing.

This paper presents a system to measure three-dimensional profile of a surface, based on the principle of scanning white light interferometry. It adopts a basic structure of Michelson interferometer and semiautomatic fast focus-adjusting mechanism. Through increasing the sampling frequency and applying the feature extracting algorithm, the precision and efficiency of measurement can be increased together.

The full wave approach is applied to one and two dimensionally rough surfaces that are characterized by Gaussian surface height probability density functions. The full wave solutions are compared with published analytical and numerical solutions for one dimensional rough surfaces. The decomposition of the rough surface into smaller and larger rough scale surfaces is not restricted by the small perturbation limitations when the two-scale full wave approach is used. Thus the mean square height of the smaller scale surface is not restricted to small values. In the small slope limit, the total rough surface is regarded as a small scale surface and the corresponding solution is given by the single scatter original full wave solution. In the high frequency limit, the total rough surface is regarded as a large scale surface and the full wave solution reduces to the physical optics solution. For the intermediate two-scale case, the radar cross sections are obtained by regarding the rough surface as an ensemble of arbitrarily oriented patches of small scale surfaces that ride upon the large scale surface. The rough surface radar cross sections are expressed as weighted sums of two cross sections. It is shown that the full wave solutions are stationary over a wide range of patch sizes.

Tilt-Invariant Approximation is used in the frame of the admittance-operator formalism ft the scattering theory. The result is an explicitly-reciprocal formula for the scattering amplitude which is accurate up to the third order of the perturbation series, and is equivalent to the Kirchoff's approximation in the high-frequency limit.

The analysis presented in this paper focuses on the calculation of the scattering cross-section of randomly rough canonical three-dimensional objects. The scattering cross- section of objects is calculated by the Small Slope Approximation (SSA) method. The SSA method was suggested by Voronovich. The small parameter of the method, the roughness slope, differs from those used in classical approaches since it is independent of the incident electromagnetic wavelength. Second-order terms in SSA method have been implemented in order to obtain accurate results for a large range of slopes. Specific developments have been carried out for the TM case which presents a singularity. In this paper we discuss the theoretical SSA solution. Calculations are presented for both polarizations of the electromagnetic field. Numerical simulations with higher order contributions of SSA method and comparisons with published results will be discussed in this paper.

We calculate the short-range contributions C⁽¹) and C⁽¹⁰) to the angular intensity correlation function for the scattering of s-polarized light from a one-dimensional random interface between two dielectric media. The calculations are carried out on the basis of a new approach that separates out explicitly the contributions C⁽¹) and C⁽¹⁰) to the angular intensity correlation function. The contribution C⁽¹) displays peaks associated with the memory effect and the reciprocal memory effect. In the case of a dielectric-dielectric interface, which does not support surface electromagnetic surface waves, these peaks arise from the coherent interference of multiply-scattered lateral waves supported by the interface. The contribution C⁽¹⁰) is a structureless function of its arguments.

There is an inverse relationship between surface brightness and polarization in the wavelength range from the ultraviolet to the near infrared. This relationship was first observed by the French astronomers B. Lyot and A. Dollfus in the early 20th century for planetary surfaces and laboratory models. The relationship was later confirmed principally by Egan and his coworkers in the Grumman Research Department in lunar simulation experiments prior to the Lunar Module landing. The observations indicate that the percent polarization (The percent polarization is the ratio of the difference between two orthogonal polarized measurements ratioed to the sum multiplied by 100) is an inverse function of the surface brightness (albedo). The Grumman instrument was a unique large scale polarimeter/photometer that allowed measurements not only of coated surfaces, but of particulates or structural surfaces up to 10 centimeters in diameter. It was found that, for instance, a diffuse surface having a reflectance of 2% could have a percent polarization of nearly 100%. The polarization was found to be a function of the optical complex index of refraction of the surface and the surface structure, and the relationship was found to be true for farm soils, agricultural and forested areas and was useful to characterize them. Astronomical and recent laboratory data will be presented to illustrate the relationship. More recent polarimeters will be discussed that permit polarization measurements accurate to plus or minus 0.1% from 0 to 100%.

A modification to the mathematical representation of shadowing and obscuration (SO) in the Maxwell-Beard BRDF model is proposed to better represent actual SO data and subsequently improve the accuracy of model predicted values of BRDF. The SO function is an empirical dual peak mathematical expression originally developed for smooth first surface layer opaque material, such as semi-gloss and gloss paints. Adding variability to forward scattering of the SO function allows a better fit to more sample types. The result is a more accurate prediction of BRDF values for model non-compliant samples such as brick, concrete, asphalt, and paints with high concentrations of extender pigment. Data were collected and analyzed for both model compliant and non-compliant samples. The proposed model changes were implemented through use of an interactive spreadsheet. Results for compliant and non- compliant samples were compared using the original and modified model. Model compliant samples showed little improvement, while non-compliant samples often showed marked improvement.

The study deals with coherent and incoherent optical scattering from rough surfaces. The purpose is to analyze the evolution of the properties when the angle of incidence varies. A numerical study is led for one-dimensional randomly rough surface by means of both surface integral method and approximate Rayleigh random grating methods. The evaluation of the surface coherent intensity reflection factor is detailed for both numerical techniques. The problem is considered for a general dielectric homogeneous material. Numerical results are presented in the case of different absorbing dielectric materials, and for reflecting materials as metals in the infrared range or as SiC around 11 micrometer. The angular domain concerned goes from normal incidence to the mean surface up to very oblique angles such as 70 degrees. Results are presented for the different materials for the coherent intensity reflection factors and for the diffuse reflection patterns in relation to the angle of incidence and to the roughness parameters. Comparisons are given with the Kirchhoff Approximation model.

There has been increasing interest in the measurement, validation, and parameterization of the bidirectional reflectance distribution function (BRDF) from surface coatings for image simulation and rendering, and design models of coating systems. The complexity of data required depends on the finish or final appearance of the surface coating. In particular the development of optical effect pigments places heightened requirements on the BRDF data needed for adequate characterization of a surface coating. Measurements of the BRDF are presented from pigmented films representative of the top layer of a paint coating. The measurements investigate the scattering characteristics of pearlescent pigments as a function of the incident polar angle and the polar and azimuthal scatter angles, including a study of the spectral variation of the BRDF across the visible waveband from 350 nm to 800 nm. In addition, measurements of linearly polarized BRDF as a function of incident and reflected directions are reported. The measurements emphasize the various optical properties of coatings such as surface and volume scattering and polarization contributions, which need to be considered if the data is to be accurately modelled or parameterized and used effectively.

We report the experimental study of the enhanced backscattering from a random rough surface through dye-doped polymer. The sample is a two-dimensional rough gold surface with a large slope coated with Pyrromethene-doped polymer layer. The sample is illuminated with an s-polarized He-Ne laser, which is pumped by a CW Argon Ion laser. The amplified scattering is measured. It is found that the enhanced backscattering peak is sharply increasing and the width is narrowing for a sample with low dielectric constant (epsilon) ₂ .

In this paper, we present the experimental results of the dynamic behavior of speckles from rough surface scattering to verify the validity of the theoretical analysis. Recently, McGurn and Maradudin have predicted an additional short-range correlation C⁽¹⁰), which shows symmetry of speckles around the specular direction in the far-field scattering from a rough surface. We have measured this peak with a two- dimensional rough dielectric film on a glass substrate. We have also measured the speckle trucking in the specular direction, the rotation invariance, and the time-reversed speckle memory effect with a one-dimensional rough dielectric film on a glass substrate.

Bidirectional ellipsometric measurements were conducted on a model system containing spherical particles on silicon surfaces coated with dielectric polymer films. The principal angle of polarization, (eta) ^(p), and the degree of linear polarization, P_L^(p), of the light scattered into directions out of the plane of incidence were measured using p-polarized, 532 nm light. Results are presented and compared to those from particles on a bare silicon substrate. Spheres of diameter 181 nm and 217 nm and film thicknesses ranging from 55 nm to 140 nm were used to test two theoretical models for light scattering: a Mie-surface double-interaction approximation and a finite-element time-domain implementation of Maxwell's equations. The measurements and the modeling demonstrate the application of bidirectional ellipsometry for characterizing the sizes of particulate contaminates on surfaces.

A multidetector optical scattering instrument is described and characterized. The instrument has twenty-eight detectors surrounding and substantially covering the scattering hemisphere. Each detector contains a polarizer so that each is only sensitive to p-polarized scattered light. The polarization of the incident light is linear and can be rotated into any angle. With this instrument, polarized light scattering measurements can be performed in multiple directions at once. The utility of this instrument is demonstrated by measuring the light scattered from a microrough silicon sample and silicon surfaces containing different sizes of polystyrene latex spheres. The results are compared to the predictions of theoretical calculations. It is shown that the distribution of polarization parameters for each of the different sizes of spheres and for microroughness are different. It is expected that designs similar to the one presented here will allow for improved on-line characterization of defects on smooth surfaces.

By using a diode array detector and an in-plane scattering geometry, we have investigated the diffraction from various etch-front morphologies. We can obtain an angular distribution of light intensity profile within 30 milliseconds. A series of experimental work, including the detailed characterization of Si backside surfaces and the morphology of Al films on Si during chemical corrosion, will be presented. The corresponding roughness parameters for different surfaces were extracted from light scattering profiles, and compared with those from real-space images. Real time measurements have been performed to study the evolution of Si surface morphology during wet chemical etching. RMS roughness, pits density, correlation length, and pits formation rate can be determined in real time.

Experimental results are presented for the angular correlation function of far-field speckle patterns scattered in the double passage of waves through a one-dimensional random phase screen. The experiment for the correlation measurement was set up to use a CCD camera to obtain the image of the speckle patterns in the scattering directions for each given angle of incidence; the cross-correlation function is then calculated from the digitized images. Recently, McGurn and Maradudin have predicted an additional short-range correlation C⁽¹⁰), which shows symmetry of speckles around the specular direction in the far-field scattering from rough surface. Similarly, the theoretical analysis of the symmetry of speckle patterns around the backscattering direction and the motion of the speckle, as the source is moved, made by Escamilla are verified experimentally in this paper.

The shadow projection method is used in industrial applications for quality control of turned workpieces. The workpiece is illuminated with collimated laser radiation, and the shadow of the workpiece is detected by a scan using CCD lines without lenses. The movement and rotation of the workpiece allow the control diameters and lengths at different positions, and the determination of eccentricity. Together with the measurement of surface roughness by analysis of the diffraction pattern, the complete monitoring of turned workpieces is possible, using only one scan. Results show how the extension of the shadow projection method for roughness measurement can be done.

A real-time two-color laser speckle-shift strain-measurement system based on the technique of Yamaguchi is utilized to detect 1D strain in small diameter structural fibers. These measurements were performed using the dual-wavelength light output from an Argon Ion laser as the light source, coupled into two separate single-mode optical patchcords. The output of each optical patchcord is incident on the test specimen experiencing strain. This structural fiber is pulled in one direction while shifting speckle patterns reflected off the fiber are detected and strain is calculated in real-time (up to 150 frames/second). Two linear CCD arrays detect the speckle pattern with image processing performed by a hardware correlator. The strain resolution of this device is 20 (mu) (epsilon) . Measurements were obtained at room temperature and attempts were made at elevated temperatures. This system is designed to be compact and robust and does not require surface preparation of the structural fibers.

The Surface-Enhanced Raman Scattering (SERS) spectra of the virions of four kinds of insect virus: Nuclear polyhedrosis virus of Trabala Vishnou (TvNPV), Nuclear polyhedrosis virus of Gynaephora ruoergensis (GrNPV), Granulosis Virus of preris rapae (PrGV) and Granulosis Virus of Darna trima (DtGV) adsorbed on the surface of silver colloid particles have been obtained and investigated. The strong interactions appeared between silver surface and COO^- groups, NH₂ groups or aromatic side-chains in SERS of the molecules of the virions. The intensities of bands related to the vibrations of COO^- groups are 458 to approximately 460 cm^-1: (upsilon) (COO^-), 568 to approximately 577 cm^-1: w(COO^-), 614 to approximately 624 cm^-1: (delta) (COO^-), 914 to approximately 934 cm^-1: (upsilon) (C-COO^-) and the bands related to the vibrations of NH₂ groups are 1114 to approximately 1134 cm^-1: t(NH₂), 1620 to approximately 1632 cm^-1: (delta) (NH₂), 3390 to approximately 3398 cm^-1: (upsilon) (NH₂). It indicates that the molecules of the virions adsorbed on silver through both the COO^- and NH₂ groups. The short-range enhancement results from a chemical interaction between the virion molecules and the silver surface. The bands at low frequency (218 to approximately 236 cm^-1) in the SERS spectra of the four samples show that chemiscorption is a main mechanism on silver hydrosis of the virion. The (pi) -electron systems of side-chains of the aromatic amino acids in virion have formed the additional adsorption centers in the molecules of virions, it will decrease the distance between some groups of molecules and the silver surface. So the bands at 928, 914, 930, 934 cm^-1, due to the skeletal C-C vibration, have been enhanced.

A continuous reduction of design rule in the semiconductor industry requires more than the present state-of-the-art laser surface scanners can achieve. In this paper, a description is given of the proposed methodology which possibly enhance the sensitivity in the detection of surface defects and particles. In the methodology, concentric two beams, long-focused and short focused beams, are incident on the surface. The scattered signal of each beam is detected alternatively, and subtracted. While the haze (mocroroughness signal) is only slightly changed, the defect signal change considerably. The present scattering formula has been modified for the theoretical consideration, and the scattered signal in the incidence plane has been numerically calculated with the appropriate parameter values. The results are presented and more discussions about the advantages of the method are described.

In this work we present an application of the forward-angle light scattering (FAST) for the flocculation point determination in asphaltene-toluene solutions. This technique allows to obtain an accurate and precise flocculation point determination compare to those obtained by traditional techniques. Estimations of flock dimensions based in the FAST measurements are presented.

Molecular absorption and fluorescence studies of Asphaltenes in toluene solution and thin films absorbed onto glass plates were carried out. The fluorescence was induced by two different type of laser: a CW Ar⁺ and Nd-Yag laser. A red shifted was observed in both: fluorescence and absorption spectra, which can be attributed to asphaltenes aggregation. Experiments made with sample films in glass plate with the 532 nm Nd-Yag laser, shows a very narrow band at 566.1 nm (1126 cm^-1) but with higher relative intensity compare to those obtained with CW laser, which is attributed to a Raman line. This signal can be employed to perform adsorption studies onto solid surfaces.