This PDF file contains the front matter associated with SPIE Proceedings Volume 7065, including the Title Page, Copyright information, Table of Contents, Introduction (if any), and the Conference Committee listing.

We obtain a single integral equation for the scattering amplitude and for the transmission amplitude for light of s polarization incident on a free-standing or supported film, both of whose surfaces are one-dimensional rough surfaces.

On the basis of the geometrical optics limit of the Kirchhoff approximation we design a one-dimensional random interface between two dielectric media that refracts p- or s-polarized light incident on it at an arbitrary angle of incidence θ0 from one of them into the other at an arbitrary but specified angle of transmission θt that is not defined in terms of θ0 by Snell's law. We call such transmission nonstandard refraction.

In previous papers the basic problem of imaging the scatter distribution of an aperture by means of catadioptrical scatterometrical devices has been shown to be reducible to the imaging of the caustic of the--preferably elliptical--mirror used as primary element. In an geometrical-optical approach this caustic is the object to be mapped onto a planar sensor by a secondary imaging optical device. Since the caustic is not a plane object, care has to be taken for the field of depth of the secondary optics. While in symmetrical alignments the caustic's area of interest is usually flat enough to be treated as a plane perpendicular to the optical axis, in so called off-axis devices the violation of the conditions known as Scheimpflug- and Hinge-principles become remarkable. Similar problems occur with the primary aperture image in dioptrical devices. The current paper deals with an extended geometrical-optical approach to non-goniometric scatterometer design, suitable for highly unsymmetrical and off-axis devices.

We have developed a system to measure the directional thermal emission from a surface, and in turn, calculate its emissivity. This approach avoids inaccuracies sometimes encountered with the traditional method for calculating emissivity, which relies upon subtracting the measured total reflectivity and total transmissivity from unity. Typical total reflectivity measurements suffer from an inability to detect backscattered light, and may not be accurate for high angles of incidence. Our design allows us to vary the measurement angle (θ) from near-normal to ~80°, and can accommodate samples as small as 7 mm on a side by controlling the sample interrogation area. The sample mount is open-backed to eliminate shine-through, can be heated up to 200 °C, and is kept under vacuum to avoid oxidizing the sample. A cold shield reduces the background noise and stray signals reflected off the sample. We describe the strengths, weaknesses, trade-offs, and limitations of our system design, data analysis methods, the measurement process, and present the results of our validation of this Variable-Angle Directional Emissometer.

Under a contract with the Air Force Phillips Laboratory, two proposed methods for enhancing spectral content of hyperspectral remote sensing data are discussed. The first method would use diffuse sky light in which specular solar reflection from the 1st surface is absent. Characteristic material emission spectra would be observed from a much wider range of view angles than for a sunlit scene. In diffuse light, the observed polarization is reduced in comparison to the sun lit case, because the non-polarized volume radiance is increased relative to the 1st surface scatter. Hence, diffraction grating artifacts due to polarized inputs are reduced. In a second method, a polarizer positioned in front of a hyperspectral imager, is shown to enhance spectral contrast by reducing polarized 1st surface reflections in forward scatter directions. A polarizer of known orientation improves diffraction grating performance because changes in the polarization dependent grating efficiency can be accounted for through calibration. In support of these methods, polarimetric bidirectional reflectance distribution function (BRDF) data from the visible grating spectral polarimeter (VGSP)¹ with wavelength range (375nm to 900nm) is presented. This data indicates that angular scatter or the BRDF from many outdoor materials may be decomposed into a polarimetric 1st surface single scatter component with little spectral variation and a diffuse or multiple scattered component having a significant spectral dependence.

A theoretical model of optical scattering in materials consisting of densely packed spherical particles is developed that can be used to predict its optical properties given its physical characteristics. The inputs to this model are the waveband of interest, the complex refractive indices and particle size distribution of the materials that comprise the media (including any contaminants), the density and sizes of any contaminants in the media, and the dimensions of the media slab. The outputs of this model are the specular transmittance and emissivity vs. wavelength of the media, and it's Bidirectional Scattering Distribution Function (BSDF) vs. scatter angle vs. wavelength. The results of this model are compared to measured transmittance and BSDF data from optical ceramics comprised of densified nanopowders (nanocomposite optical ceramics).

In this paper, we report a recent design and experimental results of an optical feedback technique for the setup of Collett-Wolf beam, which is a partially coherent source. A large negative and positive shift for a mirror with a dielectric slab backed by a metal is tested. The Collett-Wolf beam with Goos-Haenchen effect will further reduce speckle contrast by means of an ensemble average of many feedback beams.

The point spread function (PSF) of an X-ray mirror is determined by its surface topography. A new attempt is made to cover the full range of random surface roughness from macroscopic to microscopic imperfections, which has not been possible in the past. The angular deflections imposed by geometric slope errors are compared with diffraction angles which are calculated for each spatial frequency of the Fourier spectrum of the surface profile. A critical frequency has been found at which the regimes of geometric and diffraction optics separate, enabling easy calculation of the full PSF. The well-known expression of the Rayleigh scattering factor is shown to hold also separately for each spatial frequency. Furthermore, for frequencies greater than the critical frequency the total microroughness is shown to be as low as to allow the application of the existing scattering theories in the smooth surface limit. At lower spatial frequencies geometric slope errors dominate.

An instrument, the Complete Hemispherical Infrared Laser-based Reflectometer (CHILR), has been designed and built for the accurate characterization of the total reflectance of highly absorbing samples and cavity structures down to the level of 10^-5. The design of CHILR employs a number of the same features of Total Integrated Scatter (TIS) measurement devices, but is used for total reflectance (both specular and diffuse components), rather than only the diffuse component. A number of features of CHILR include spatial uniformity and angular dependence of reflectance measurement capability, multiple wavelength laser sources, and the ability to measure a wide range of sample sizes and cavities with aperture sizes, ranging from 3 mm to 51 mm. We address several basic issues of alignment, background and externally scattered light, reference measurement, and laser drift, for the CHILR. We also present results of several examples, including cavities for blackbody sources, and radiometer cavities.

Numerical, theoretical and experimental results on the use of combinations of surface plasmons, waveguide and diffraction modes to control the flow of light in transmission gratings, are described. Methods of designing compound gratings that have multiple, differently composed grooves within each period and that selectively transmit, at anomalously large amounts, s-polarized or p-polarized light, are described. It is shown how the ability to separate the polarization components and have them transmitted into different portions of the substrate can be used to design polarimetric sensors. Related phenomena of light circulation and weaving due to the excitation of phase resonances are described.

Scatterometry of macroscopically plane surfaces with micro-roughness by using quasi-parallel illumination is widely investigated. Measuring light scatter from surfaces with a certain macroscopical curvature under the same conditions leads to the question of distinguishing the effects of micro-roughness from those of curvature in the resulting scatter distribution. This is especially true for micro-roughness far beyond the smooth surface criterion. For example, the scatter distribution of a cone with comparatively heavy traces of machining along a plane through the axis of symmetry will be wide-spread perpendicularly to that plane for both reasons, the scatter pattern of the machining marks and the curvature of the surface. To extract the desired scatter pattern, the curvature has to be compensated by means of additional optical systems. The current paper deals with theory and basic design approaches, which are to be continued in follow-up papers.

We present a novel image-based BRDF (Bidirectional Reflectance Distribution Function) measurement system for materials that have isotropic reflectance properties. Our proposed system is fast due to simple set up and automated operations. It also provides a wide angular coverage and noise reduction capability so that it achieves accuracy that is needed for computer graphics applications. We test the uniformity and constancy of the light source and the reciprocity of the measurement system. We perform a photometric calibration of HDR (High Dynamic Range) camera to recover an accurate radiance map from each HDR image. We verify our proposed system by comparing it with a previous imagebased BRDF measurement system. We demonstrate the efficiency and accuracy of our proposed system by generating photorealistic images of the measured BRDF data that include glossy blue, green plastics, gold coated metal and gold metallic paints.

Tiny droplets deposited on a copper plate were controlled and measured by a developed control technique and by using a simplified optical apparatus, white light and laser light. The technique employs the proportional control combined with shifting movement by an integrator. The droplets were controlled constant for thirty minutes at the preset level of the intensity of scattered light in a control circuit. The droplets were almost a hemisphere form in initial condensation at room temperature and were few tens micrometers in diameter. The controlled mass of a dew droplet was obtained from the volume of its shape and was of the order of 10-8 g.

Five methods for the measurement of absolute reflectance are described and compared. Four of the methods, the V-W, V-N, integrating sphere and goniometer methods, have been in use for a number of years. The fifth is a new STAR GEM method. The acronym of STAR GEM is from the capital letters of Scatter, Transmission, and Absolute Reflection measurements using a Geminated Ellipsoid Mirror. Only the goniometer and STAR GEM methods can be used to measure reflectance and transmittance at almost any angle of incidence. The STAR GEM is used in conjunction with an FTIR (Fourier-Transform Infrared) spectrophotometer and also with a grating spectrophotometer to make reflectance and transmittance measurements in the wavelength region from 0.24&mgr;m to 25&mgr;m. Ordinate errors of the FTIR spectrophotometer are estimated from measurements in the overlapping wavelength region made by both spectrophotometers. A reflectance measurement of a non-plane surface, such as a surface of micro-ball lenses, can also be made using the STAR GEM.

Light depolarization due to multiple scattering in tissue is an interesting bio-medical issue. The bio-tissue is made of anisotropic molecules. Using a simple ellipsoid model, the polarization property of single anisotropic bio-molecule has been investigated theoretically. We extend this theory to a bio-tissue that is modeled as a system of non-correlated anisotropic molecules. Based upon a statistical model of anisotropic distribution, the scattering depolarization effects are investigated. The simulated molecular orientation-dependent single scattering depolarization Ds (1) and the double scattering depolarization Ds (2) are reported. Ds (2) contribution is more important for high density scattering medium. This theory has provided a simulation tool for investigating the depolarization effect in the highly scattering bio-medium.

An isotropic medium can consist of a system of spherical particles as well as anisotropic particles with perfectly random orientation. Even though the scattering particle is spherical, the anisotropic geometry of the incident and scattering direction can cause polarization in the scattering beam. For a system of randomly oriented anisotropic particles, both polarization and depolarization exist. This work reports the polarization and depolarization of dipole scattering for such an overall isotropic system whose anisotropic particles are ellipsoids by using both the Jones matrix and Mueller matrix formulations.

Pharmaceutical initiatives use analytical tools to monitor powders flowing through granulating, blending, and tablet formation steps. Two critical parameters that drive the quality and efficiency of drugs are the concentration of actives in the tablet, and the dissolution properties of the tablet. In order to ensure that these are within the target design space, it is important that component concentrations, particle size distributions, and cluster size are monitored throughout the manufacturing process. Standard optical techniques detect scattered light from spots that encompass many components in the blend. Efforts to extract composition and blend uniformity based on chemometric analyses are complex and often intractable. A highly spatially resolved spectral imager could simplify the chemometrics if the effective spatial resolution can separate most particles from neighboring particles. The effective spatial resolution is a function of the incident spot size, multiple scattering events, and the collection optics. This paper assesses the degree of spectral mixing due to particle-particle scattering as a function of incident spot size. Our real-time optical design is enabled by a high spectral brightness supercontinuum source, a MEMs-based spectral scan mechanism, confocal spatial scanning optics, and high gain * bandwidth detection.

Shade-screens are widely used in commercial buildings as a way to limit the amount of direct sunlight that can disturb people in the building. The shade screens also reduce the solar heat-gain through glazing the system. Modern energy and daylighting analysis software such as EnergyPlus and Radiance require complete scattering properties of the scattering materials in the system. In this paper a shade screen used in the LBNL daylighting testbed is characterized using a photogoniometer and a normal angle of incidence integrating sphere. The data is used to create a complete bi-directional scattering distribution function (BSDF) that can be used in simulation programs. The resulting BSDF is compared to a model BSDFs, both directly and by calculating the solar heat-gain coefficient for a dual pane system using Window 6.

We propose a method for the characterization of one- and two-dimensional diffraction gratings by means of the measurement of diffraction efficiencies. The method is based on the comparison of measured and calculated efficiencies. For the numerical calculation we use the Rigorous Coupled Wave Analysis RCWA and an optimization algorithm to determine the grating shape that fits best to the measured data. We analyzed in which cases the method is able to determine the grating shape without ambiguity and which measurement parameters should be used. By systematically analyzing a given inverse problem, we try to derive the theoretical limits of the method.

Moisture content (MC) is an important quality factor that is measured and monitored, at various stages of processing and storage, in the food industry. There are some commercial instruments available that use near infrared (NIR) radiation measurements to determine the moisture content of a variety of grain products, such as wheat and corn, with out the need of any sample grinding or preparation. However, to measure the MC of peanuts with these instruments the peanut kernels have to be chopped into smaller pieces and filled into the measuring cell. This is cumbersome, time consuming and destructive. An NIR reflectance method is presented here by which the average MC of about 100 g of whole kernels could be determined rapidly and nondestructively. The MC range of the peanut kernels tested was between 8% and 26%. Initially, NIR reflectance measurements were made at 1 nm intervals in the wave length range of 1000 nm to 1800 nm and the data was modeled using partial least squares regression (PLSR). The predicted values of the samples tested in the above range were compared with the values determined by the standard air-oven method. The predicted values agreed well with the air-oven values with an R2 value of 0.96 and a standard error of prediction (SEP) of 0.83. Using the PLSR beta coefficients, five key wavelengths were identified and using multiple linear regression (MLR) method MC predictions were made. The R2 and SEP values of the MLR model were 0.84 and 1.62, respectively. Both methods performed satisfactorily and being rapid, nondestructive, and non-contact, may be suitable for continuous monitoring of MC of grain and peanuts as they move on conveyor belts during their processing.

This paper summarizes the Representative Layer Theory of diffuse reflection, and contrasts it with other mainstream theoretical approaches. A brief historical perspective is provided on the development of modeling strategies, broadly classified as those using continuous and discontinuous mathematics. It is shown that a sample composed of a series of distinct layers can be modeled straightforwardly and accurately using a discontinuous approach. The focus of the paper is the Representative Layer Theory, which broadens the discontinuous modeling approach so that it is applicable to particulate samples. Experimental data validating the Representative Layer Theory is presented and the theory will be shown to explain some observed physical phenomena that were long known but not well understood. Examples are drawn from Near-Infrared Spectroscopy but the modeling approaches presented are applicable to other types of spectroscopy.

The TETRA bi-directional reflectance distribution function (BRDF) model was developed to simulate the reflection from random rough surfaces in optical radiation transfer modeling by the Monte Carlo method (MCM). This procedural model is based on geometrical optics, has as a prototype the two-dimensional model proposed by Torrance and Sparrow, and allows generating, for each ray, a random tetrahedral pit with walls that reflect according to Fresnel's law. An incident ray undergoes one or several reflections from the tetrahedron's walls, and then continues to participate in the radiation transfer on the macro-level. The properties of the TETRA BRDF are studied using numerical experiments.

The aim of this work is to contribute to a better determination of the optical parameters for dense scattering media. We study the interaction of femtosecond polarized light pulse with a scattering medium considering Monte Carlo simulation. The Monte Carlo scheme is based on temporal photon tracking, including a pseudo Monte Carlo approximation associated to two small detectors in forward and backward directions. The statistical scattering properties are derived from temporal phase matrices, which are evaluated through a scanning of frequency associated to the Lorenz-Mie theory. We specially focused our attention on solid rocket motor modelling. In such scattering medium, large optical thickness, various bimodal particle size distributions and concentration gradients could be observed. Moreover, such media consists in a suspension of big particles (typically 100 &mgr;m diameter). The understanding of the scattering process of such particles needs the introduction of Debye modes. We will explain the contribution of these modes and give an example with a numerical application.

Materials with similar chemical compositions often exhibit different optical properties due to their structural composition. PTFE is widely used in many applications for both its mechanical and optical properties. Low density sintered PTFE has optical properties that make it desirable for use as a white diffuser in applications such as remote sensing. The contrast between the commonly available high density material and the low density material may be useful for those interested in optical modeling of scattered light. Additionally, some applications may find high density PTFE suitable for some optical applications. This paper describes measurements of BRDF, 8º/hemispherical reflectance, and directional hemispherical transmittance for both high density (HD) and low density (LD) sintered PTFE.

Optical density measurement is a very powerful tool to characterize particle size and physical property of scattering media such as sprays and engine injection. The major difficulty of such a measurement is the tremendous amount of scattered light: for such media, the optical density can be greater than 10. The goal of this work is to develop a new experimental tool, based on femtosecond laser technology in order to isolate (spatially and temporally) a very limited amount of non scattered transmitted light, and to measure the extinction of the media. We collect the transmitted light and we use an optical Kerr gating. This technique is very powerful to determine the time of flight of every photon in the scattering media. By fine-tuning the optical parameter of the setup, we have been able to selectively increase the gating efficiency of the ballistic part vs the diffusive part of the collected light. Furthermore, spectral tunability of amplified femtosecond laser system is straightforward. As a result, it has been possible to measure the extinction spectra of a model diffused media (SiO2 particle in water), and to determine the particle size distribution after inversion method.

The mechanical properties of the materials are related with the atomic arrangement of their constituent elements. Particularly, the electronic cloud at the surface of steels shows spatial properties of the charge distribution of the metallic crystals. In this work we report the conductivity properties of the electronic cloud in the directions normal and parallel to the surface. These conductivity features are studied through the interaction with an optical field. The reflectance components of the materials are measured and related with the conductivity in the respective directions. We show that for the different Steel samples that were measured, a relation between the hardness and the reflectance components is observed.

A STAR GEM as a scatterometer can measure diffuse reflection spectra. The acronym of STAR GEM is from the capital letters of Scatter, Transmission, and Absolute Reflection measurements using a Geminated Ellipsoid Mirror. A biconical accessory, such as the STAR GEM, has the advantage that it has very high collection efficiency and the ability to measure scattered reflected light from very small samples. However, it is generally thought of as a qualitative device. It becomes clear that the STAR GEM is superior to a goniometer on the study to measure absolute reflectance of a specular sample. Only the goniometer and its family can quantitatively measure the bidirectional reflectance distribution function (BRDF) of a sample. The purpose of this paper is to describe the possibilities and problems for the STAR GEM to measure the BRDF of a sample.

The three intensity polarizer-sample-analyzer imaging ellipsometry is used to measure the ellipsometric parameters (&PSgr;,&Dgr;). In addition to the ellipsometric parameters, we introduce an extra angle &agr; to measure the of the azimuth deviation of polarizer. After careful calibration, we found this deviation can indicate how much the surface normal slanted from the plane; then it can be used to deduce the thickness profile coated on a cylindrical lens. Using this technique, we not only can determine the radius curvature of the curved surface, we also can calculate the thickness of the thin film coated on a curved surface.

Nowdays, polymers like hydrogels that respond to well defined stimuli, have a particular interest in fields like optoelectronics, biotechnology, materials, etc. One of this polymers is the NIPAAM, that posses thermo optics properties. This work is oriented to the design and implementation of a temperature sensor using fiber optics and having as sensitive part a sintetized hydrogel of polyNIPAAM and MeOXA of reversible thermosensible characteristics. For this setup we use a glass ampoule which is coupled to two pieces of plastic, inside the ampoule it is placed the hydrogel. The working principle relies in the turbidity changes in a well known temperature called critical. We present the experimental results of the designed and implemented device.

Electromagnetic waves propagation research in volume media increases considerably in the last years. The study evolved from thick hologram gratings, Bragg and Raman-Nath diffraction regimes up to current research in photonics materials. Usually differential methods are employed to account for the light transmitted for volume media. In our proposal, we develop a simple and versatile integral method to calculate the diffracted field provided the media refractive index has low variations in a wavelength scale. In fact, starting from first principles, we obtain a modified version of the Fresnel propagator of the scalar diffraction theory. Our method is valid for some kind of magnetic, dielectric and absorbent inhomogeneous media. In particular, for TE (TM) fields, we can study media where the permittivity (permeability) gradient is perpendicular to the electric (magnetic) field and its permeability (permittivity) is constant. To validate the approach, we applied it to (in) homogeneous media having well known diffraction properties.

Background and objective: Minimal intervention dentistry (MID) calls for early detection and remineralization of initial demineralization. Laser fluorescence is efficient in detecting changes in mineral tooth content. Recaldent is a product of casein phosphopeptide-amorphous calcium phosphate (CPP- ACP) which delivers calcium and phosphate ions to enamel. A new product which also contains fluoride is launched in United States. The remineralizing potential of CPP- ACP per se, or when combined with 0.22% Fl supplied in an oral care gel on artificially demineralised enamel using laser fluorescence was investigated. Methods: Fifteen sound human molars were selected. Mesial surfaces were tested using He-Cd laser beam at 441.5nm with 18mW power as excitation source on a suitable set-up based on Spex 750 M monochromator provided with PMT for detection of collected auto-fluorescence from sound enamel. Mesial surfaces were subjected to demineralization for ten days. The spectra from demineralized enamel were measured. Teeth were then divided according to the remineralizing regimen into three groups: group I recaldent per se, group II recaldent combined with fluoride gel and group III artificial saliva as a positive control. After following these protocols for three weeks, the spectra from remineralized enamel from the three groups were measured. The spectra of enamel auto-fluorescence were recorded and normalized to peak intensity at about 540 nm to compare between spectra from sound, demineralized and remineralized enamel surfaces. Results: A slight red shift was noticed in spectra from demineralized enamel, while a blue shift may occur in remineralized enamel. Group II showed the highest remineralizing potential. Conclusions: Combining fluoride with CPP-ACP had a synergistic effect on enamel remineralization. In addition, laser auto-fluorescence is an accurate technique for assessment of changes in tooth enamel minerals.