This PDF file contains the front matter associated with SPIE Proceedings Volume 9205 including the Title Page, Copyright information, Table of Contents, Introduction, and Conference Committee listing.

The bidirectional reflectance distribution function (BRDF) is a fitted distribution function that defines the scatter of light off of a surface. The BRDF is dependent on the directions of both the incident and scattered light. Because of the vastness of the measurement space of all possible incident and reflected directions, the calculation of BRDF is usually performed using a minimal amount of measured data. This may lead to poor fits and uncertainty in certain regions of incidence or reflection. A dynamic data driven application system (DDDAS) is a concept that uses an algorithm on collected data to influence the collection space of future data acquisition. The authors propose a DDD-BRDF algorithm that fits BRDF data as it is being acquired and uses on-the-fly fittings of various BRDF models to adjust the potential measurement space. In doing so, it is hoped to find the best model to fit a surface and the best global fit of the BRDF with a minimum amount of collection space.

Applications involving space based instrumentation and aerodynamically heated surfaces often require knowledge of the bi-directional reflectance distribution function (BRDF) of an exposed surface at high temperature. Addressing this need, the Johns Hopkins University Applied Physics Laboratory (JHU/APL) developed a BRDF facility that features a multiple–port vacuum chamber, multiple laser sources covering the spectral range from the longwave infrared to the ultraviolet, imaging pyrometry and laser heated samples. Laser heating eliminates stray light that would otherwise be seen from a furnace and requires minimal sample support structure, allowing low thermal conduction loss to be obtained, which is especially important at high temperatures. The goal is to measure the BRDF of ceramic-coated surfaces at temperatures in excess of 1000°C in a low background environment. Most ceramic samples are near blackbody in the longwave infrared, thus pyrometry using a LWIR camera can be very effective and accurate.

The possibility for controlling both the probe-field optical gain and absorption switching as well as photon conversion by a surface-plasmon-polariton near field is explored for a quantum dot located above a metal surface. In contrast to the linear response in the weak-coupling regime, the obtained spectra could show an induced optical gain and a triply-split spontaneous emission peak resulting from the interference between the surface-plasmon field and the probe or self-emitted light field in such a strongly-coupled nonlinear system.

An approach to inverting experimental light scattering data for obtaining the normalized surface height autocorrelation function of a two-dimensional randomly rough dielectric surface, and its rms height is presented. It is based on the expression for the contribution to the mean differential reflection coefficient from the in-plane, co-polarized, light of s-polarization scattered diffusely from such a surface, obtained by phase perturbation theory. For weakly rough surfaces the reconstructions obtained by this approach are quite accurate.

Since the development of the Torrance-Sparrow bidirectional re ectance distribution function (BRDF) model in 1967, several BRDF models have been created. Previous attempts to categorize BRDF models have relied upon somewhat vague descriptors, such as empirical, semi-empirical, and experimental. Our approach is to instead categorize BRDF models based on functional form: microfacet normal distribution, geometric attenua- tion, directional-volumetric and Fresnel terms, and cross section conversion factor. Several popular microfacet models are compared to a standardized notation for a microfacet BRDF model. A library of microfacet model components is developed, allowing for creation of unique microfacet models driven by experimentally measured BRDFs.

Surface topography is required for many kinds of industrial products, and its applications keep increasing, making the need for adequate control of surfaces and an understanding of surface topography measurements more important than ever. In this paper, we presented a sensitive and cost-effective optical probe for surface topography. An astigmatic method used in the optical probe was optimized for submicron/nanometer resolution and monotonic characterization of focus error signal (FES). A home-made system based on this optical probe was also presented, and the measurement results of surface topography indicate great potential of applications in many industrial fields.

The broad objective of this paper is to study the surface of the corroded metals by using proximity sensor which works on the principle of light scattering by objects. The present work discussed a simple low cost sensor design making use of plastic optical fiber. The sensor used is insensitive to source fluctuation and can detect surface roughness of the metals. The average surface roughness of the samples in different concentrations of acidic medium has been studied using the sensor. The reflected light intensity from the surface of sample metals was collected and measured as a function of lateral distance to estimate the roughness of the surface. The results have been compared with the stylus measurements.

The "Bi-Directional Scattering Function" BSDF of a diffuser depends on several parameters, such as surface properties, observational conditions and further. This paper describes experimental activities to achieve a better understanding about the interaction between diffuser properties and performance with regards to its scattering behavior. For this purpose a set of 24 diffusers with defined surface properties have been manufactured and systematically been investigated in a dedicated radiometric calibration measurement facility. The experimental data are compared with existing theoretical models.

The challenge of improving component quality and reducing cost has focused the attention of the solar thermal power industry on reliable component characterization methods. Since the reflector plays a key role in the energy conversion chain, the analysis of its reflectance properties has become a lively discussed issue in recent years. State of the art measurement instruments for specular reflectance do not give satisfying results, because they do not resolve sufficiently the near specular scatter of possible low cost mirror material candidates. The measurement of the BRDF offers a better solution than the traditional approach of placing a detector in the specular reflected beam path. However, due to the requirement of high angular resolution in the range of 1 mrad (0.057°) or better and the challenge of measuring high dynamic differences between the specular peak and the scatter signal, typical commercial scanning goniophotometers capable of this are rare. These instruments also face the disadvantages of impractically long acquisition times and, to reach the high angular resolution, occupy a large space (several meters side length). We have taken on the appealing idea of a parallel imaging goniophotometer and designed a prototype based on this principle. A mirrored ellipsoid is used to redirect the reflected light coming from a sample towards a camera with a fisheye lens. This way the complete light distribution is captured simultaneously. A key feature allows the distinction of the high intensity specular peak and the low intensity scatter. In this article we explain the prototype design and demonstrate its functionality based on comparison measurements done with a commercial scanning goniophotometer. We identify limitations related in part to the concept and in part to the specific prototype and suggest improvements. Finally we conclude that the concept is well suitable for the analysis of near specular scatter of mirror materials, although less adequate for the analysis of rough surfaces that require a full 180° view angle. Results obtained with this instrument are useful to evaluate the performance of a reflector material for a specific concentrating solar collector design and also serve in other applications that require near specular scatter analysis like degradation and soiling research.

It has been established that the Raman scattering (RS) of chalcogenide glass–like semiconductors (CGS) materials As-Se-S and As-Se-Te at frequencies below 100 cm^-1 consists of two parts: first - which the intensity with increasing frequency up to 30 ÷ 40 cm^-1 decreases (quasi-elastic scattering); second - which have been observed a broad band with a maximum at frequencies of ~ 63 ÷ 67 cm-1 (boson peak - BP). Such a case is absent in the respective crystals. The observed features are associated with relaxation and excess density of states of acoustic vibrations in irregularities is localized with nanometer-size of material. It is shown that the contribution of the different types of scattering in a low-frequency range depends on the degree of disorder in the material, which varies with the change of chemical composition and by doping.

Efficient transparent light converters have received lately a growing interest from optical device industries (LEDs, PV, etc.). While organic luminescent dyes were tested in PV light-converting application, such restrictions as small Stokes shifts, short lifetimes, and relatively high costs must yet be overcome. Alternatively, use of phosphors in transparent matrix materials would mean a major breakthrough for this technology, as phosphors exhibit long-term stability and are widely available. For the fabrication of phosphor-filled layers tailored specifically for the desired application, it is of great importance to gain deep understanding of light propagation through the layers, including the detailed optical interplay between the phosphor particles and the matrix material. Our measurements show that absorption and luminescent behavior of the phosphors and especially the scattering of light by the phosphor particles play an important role. In this contribution we have investigated refractive index difference between transparent binder and phosphors. Commercially available highly luminescent UV and near-UV absorbing μm-sized powder is chosen for the fabrication of phosphor-filled layers with varied refractive index of transparent polymer matrix, and well-defined particle size distributions. Solution-processed thick layers on glass substrates are optically analyzed and compared with simulation results acquired from CROWM, a combined wave optics/ray optics home-built software. The results demonstrate the inter-dependence of the layer parameters, prove the importance of careful optimization steps required for fabrication of efficient light converting layers, and, thus, show a path into the future of this promising approach.

We present a simple method to measure the spatial coherence of a partially coherent field by analyzing far-field measurements with and without a well-characterized obscuration. From these measurements, the coherence can be estimated for all pairs of points whose centroid is the obstacle's centroid. By scanning the obstacle over the test plane, one can recover the four-dimensional coherence function. In principle, such measurements can be performed without any refractive or diffractive elements, allowing them to be done in higher frequency regimes.

Over the years we have developed an adequate theory and understanding of surface scatter from smooth optical surfaces (Rayleigh-Rice), moderately rough surfaces with paraxial incident and scattered angles (Beckmann- Kirchhoff) and even for moderately rough surfaces with arbitrary incident and scattered angles where a linear systems formulation requiring a two-parameter family of surface transfer functions is required to characterize the surface scatter process (generalized Harvey-Shack). However, there is always some new material or surface manufacturing process that provides non-intuitive scatter behavior. The linear systems formulation of surface scatter is potentially useful even for these situations. In this paper we will present empirical models of several classes of rough surfaces or materials (subsurface scatter) that allow us to accurately model the scattering behavior at any incident angle from limited measured scatter data. In particular, scattered radiance appears to continue being the natural quantity that exhibits simple, elegant behavior only in direction cosine space.

When using active-illumination systems for directed-energy and remote-sensing applications, more often than not a highly coherent laser beam propagates from the source through the atmosphere resulting in partially coherent beam illumination on the target. Interestingly enough, not much literature exists pertaining to the scattering of partially coherent light from rough surfaces. In an effort to bridge this gap, this paper develops a wave-optics simulation approach to the problem at hand. Specifically, the analysis uses two separate phase screens. The first phase screen is located in the source plane and accounts for the size and coherence properties of the incident illumination. Through multiple phase-screen realizations and far field-field propagation from the source plane to the target plane, the first phase screen allows for the generation of spatially partially coherent beam illumination with a Gaussian Schell-model (GSM) form. The second phase screen is located in the target plane and accounts for the surface parameters, i.e., the surface height standard deviation and correlation length. Through multiple phase-screen realizations in the target plane and far field-field propagation to the observation plane, the second phase screen accounts for the interaction of the incident GSM beam with a perfectly reflecting rough surface. This allows for the formulation of the average scattered irradiance and normalized autocorrelation function in the far field. Initial results show that this wave-optics simulation approach compares well with a previously validated 2D scalar-equivalent solution [Hyde et al., Opt. Express 21, 6807 (2013)].

In security operations or medical imaging the main challenge is a need for fast identification, which is possible with laser range profiler or 2D-3D laser imagery. This paper discusses scattering models for High Temporal Resolution Ladar (Laser Detection and Ranging) and 2D-3D imagery. We describe electromagnetic models of 1D, 2D and 3D laser signatures whose surface reflectance of the objects is calculated with the second order Small-Slope Approximation for polarized incident laser wave and a model of effective permittivity. The physics based model is designed to provide accurate results for the scattering from complex objects.

This paper deals with new optical non-conventional 3D laser imaging. Optical non-conventional imaging explores the advantages of laser imaging to form a three-dimensional image of the scene. 3D laser imaging can be used for threedimensional medical imaging, topography, surveillance, robotic vision because of ability to detect and recognize objects. In this paper, we present a 3D laser imaging for concealed object identification. The objective of this new 3D laser imaging is to provide the user a complete 3D reconstruction of the concealed object from available 2D data limited in number and with low representativeness. The 2D laser data used in this paper come from simulations that are based on the calculation of the laser interactions with the different interfaces of the scene of interest and from experimental results. We show the global 3D reconstruction procedures capable to separate objects from foliage and reconstruct a threedimensional image of the considered object. In this paper, we present examples of reconstruction and completion of three-dimensional images and we analyse the different parameters of the identification process such as resolution, the scenario of camouflage, noise impact and lacunarity degree.

Uniformity of conductive materials is an important property which is measured during manufacturing and in finished products, especially in electronics applications such as organic solar cells. Differences in uniformity are often very small, invisible or below the surface of the sample. Therefore, they are not always detectable even by high-resolution imaging systems. Respectively, electrical conductivity measurements are limited to those mainly between the measuring probes. Uniformity difference measurements are time-consuming in the case of a large area characterization. To bypass the described limitations, a simple heating and IR-imaging based system was designed and demonstrated with conductive materials. Samples with different defects were used to investigate the correlation of conductance and defect positioning. By making punched holes in the samples, it was possible to demonstrate how the local resistances of thin films have functions to each other and how this may be observed on an IR-figure. Thermographs of punched thin films confirm that those areas where the holes prevented the current flow have lower heat emissions. Therefore, it can also be concluded that, generally, the temperature is highest at the areas where current density is highest. When comparing the defects of bent samples to these punctured ones, the correlations of resistance and breakage areas were comparable. The applied system is capable of localizing small defects in large-area samples using a single IR-image. This is a significant advantage from the manufacturing process measurement point of view.

We present a method to recover the 3D shape of both front and back surfaces of smooth transparent objects, such as glass windows or containers. We use a combination of two methods known for the 3D reconstruction of specular surfaces: shape from distortion and shape from polarization. As each transparent surface reflects and transmits incident light, one can see two shifted images by observing the reflection of a pattern on two surfaces nearby. Looking at the reflection of one known point source on the front surface with a calibrated camera, the depth and the orientation of this surface can be determined up to a one dimensional space of solution. This ambiguity is lifted by using the degree of polarization of the reflection, which depends on the incidence angle. Supposing that the front surface is locally at, we show that there is the same ambiguity between position and orientation for the observed reflection coming from the back surface of the object. This ambiguity can again be lifted by using ray-tracing and Mueller calculus. Thus our method enables to measure both the position and the orientation of the two surfaces of a transparent object, with only one polarimetric image. We present an experiment on real objects to evaluate this method.

X-ray luminescence computed tomography (XLCT) is a novel molecular imaging modality that reconstructs the optical distribution of x-ray-excited phosphor particles with prior informational of anatomical CT image. The prior information improves the accuracy of image reconstruction. The system can also present anatomical CT image. The optical system based on a high sensitive charge coupled device (CCD) is perpendicular with a CT system. In the XLCT system, the xray was adopted to excite the phosphor of the sample and CCD camera was utilized to acquire luminescence emitted from the sample in 360 degrees projection free-space. In this study, the fluorescence diffuse optical tomography (FDOT)-like algorithm was used for image reconstruction, the structural prior information was incorporated in the reconstruction by adding a penalty term to the minimization function. The phosphor used in this study is Gd2O2S:Tb. For the simulation and experiments, the data was collected from 16 projections. The cylinder phantom was 40 mm in diameter and contains 8 mm diameter inclusion; the phosphor in the in vivo study was 5 mm in diameter at a depth of 3 mm. Both the errors were no more than 5%. Based on the results from these simulation and experimental studies, the novel XLCT method has demonstrated the feasibility for in vivo animal model studies.

The principal foundations, specific features and application fields of the advanced highly sensitive method of gas impurities detection - molecular condensation nuclei (MCN) method are discussed. MCN method is based on the conversion of impurity molecules to condensation nuclei of much larger size followed by the nuclei enlargement in the supersaturated vapor of specially selected low-volatile organic substances and detection of produced aerosol particles using an optical (nephelometric) method. The light scattering properties of the aerosol particles and air in the photometer of an MCN detector as well as sensitivity of the photometer’s photodetector are investigated. We have determined that the light scattering by aerosol particles is interferometric by nature and is comparable within an order of magnitude with light scattering by the air inside a photometer. The threshold sensitivity of fotointegrator was reduced a level where the detection limit for the gas analyzer target component is determined by the background level of spontaneous condensation and not by the sensitivity of the detector’s photoreceiver.

The French Laser MégaJoule (LMJ) is a high power laser project, dedicated to fusion and plasma experiments. It will include 176 square beams involving thousands of large optical components. The wavefront performances of all those optics are critical to achieve the desired focal spot shape and limit the hot spots that could damage the components. The CEA has developed experimental methods to qualify precisely the quality of the large optical components manufactured for the project and measure the effect of various defects. For specific components (coated or parabola mirrors, lenses or gratings), classical techniques like interferometric setups may fail to measure the wavefront highest spatial frequencies (> 1 mm^-1). In order to improve the measurements, we have proposed characterization methods based upon a laser beam diffraction interpretation. They present limits and we need to improve the wavefront measurement for high spatial frequencies (> 1 mm^-1). We present in this paper the intermediate field measurement based upon the Talbot effect theory and the Fourier analysis of acquired intensity images. The technique consists in a double pass setup: a plane wave is transmitted through the component twice, to simplify the setup and improve the measurement. Then, intensity images are acquired at different distances with a CCD camera and lead to the wavefront power spectral density. We describe the experimental setup to measure the wavefront of large specific components. We show experimental results. Finally, we discuss about the advantages and the limits of such a method, and we compare it with our previous measurement methods.

We study interaction of structured illumination with randomly scattering media. Based on the equations of scalar diffraction theory we perform a numerical simulations of the propagation of a structured illumination through various scattering media. Applying the continuous sequential algorithm of adaptive phase optimization for focusing a scattered wavefront to a target, we explore the resulting phase distributions at the input and output of the scattering media. We demonstrate that corrected wavefront takes a spherical shape, which can be removed for imaging through the scattering sample. According to the obtained results the using scalar diffraction theory extends the limits of applicability of the sequential adaptive phase optimization algorithm beyond the focusing, making they as broad as in transmission matrix method.

An optical system for the generation of a beam with a variable and controllable polarization status has been designed, realized and tested. The system is based on an interferometric set up, consisting of a splitting system, a phase delay system and a recombination system. By controlling the optical path, it is possible to obtain every polarization status: linear, elliptical and circular. The system can be realized with an all reflective scheme and it can work in a wide spectral band of the electromagnetic spectrum, from the near-infrared down to the extreme ultraviolet. The system can be integrated in different optical setups in order to enhance their versatility, such as in laser devices, optical instrumentations, synchrotron lines or free electron lasers beam transport system. Finally it can be also used to test optical device and for calibration of optical components.

Multifunctional automated system of 2D laser polarimetry of biological tissues with enhanced functional capabilities is proposed. Two-layer optically thin (attenuation coefficient τ ≤ 0,1 ) biological structures, formed by "muscle tissue (MT) - the dermis of the skin (DS)" histological cryosections for the two physiological states (normal - dystrophy) were investigated. Complex of objective indexes which characterized by 2D polarization reproduced distributions under the following criteria: histograms of the distributions; statistical moments of the 1st - 4th order; autocorrelation functions; correlation moments; power spectra logarithmic dependencies of the distributions; fractal dimensions of the distributions; spectra moments are presented.

Model human epidermal samples are used for transmission measurements at varying ambient humidity. Light is used from four different light emitting diodes (LEDs), of UVA wavelength of 365nm, and three visible wavelengths of 460nm, 500nm, and 595nm. A humidity-controlled chamber was used to house the samples while transmission measurements were taken. Many different types of measurements were taken, including raising ambient humidity from 20% to 75% then adding 0.5mL of water to the sample; lowering humidity from near 100% to 60%; and alternately raising and lowering of the ambient humidity. The results show higher transmission of light through the samples at very high ambient humidity, about 100%; whereas the transmission is much lower at lower ambient humidity. A simple model of epidermis as a turbid medium and reduced light scattering by refractive index matching is used to explain the results. Implications of these results are discussed.

We analyze the scattering field generated by the coherent illumination of a three-dimensional transmittance characterized by a slit-shape curve. Generic features are obtained by using the Frenet-Serret equations which allows a decomposition of the scattering field. The analysis is performed by describing the influence of the curvature and torsion on osculating, normal and rectifying planes. Focusing and bifurcation effects are predicted and corroborated experimentally.