Polarization of both Reflection and transmission scatterings by a rough plane surface of a glass hemisphere with a smooth spherical surface were measured. Null ellipsometry was used to measure the ellipsometric parameters and depolarization. Linear polarization, circular polarization, and principal Mueller matrix were obtained from the above measured quantities. Scattering was measured at fixed incident and detection directions, and variable sample orientation. The scattering and its polarization and depolarization are symmetric with the off-specular angle (OSA). The measured linear polarization increases with increasing OSA, and may change sign for large OSA. Reflection scattering shows more depolarization than the transmission scattering and so do the deviations from the specular values for all parameters.

The full polarization property of a holographic volume grating sample is investigated both theoretically and experimentally. There exists strong interaction between the transmitted and diffracted beams due to the grating diffraction of orders m=-1 and 1. Based upon a volume grating mode, the diffracted fields and Mueller matrices of the interacting transmitted and diffracted beams were first analytically derived. The formalism is derived for the general case that the diffraction beam and the grating wave-vector are not in the plane of incidence, where s-waves and p-waves are not de-coupled. For a single-hologram grating sample, the Mueller matrix is measured at wavelength 632.8 nm and in good agreement with the theory. The result demonstrates a correlation between the diffraction strength and the polarization properties of the volume holographic grating. The derived algorithm has provided a simulation analysis tool for the engineering device design of real holographic beam combiner/splitter (HBCS) devices.

Recently a physical medium was fabricated in which both the effective permittivity and the effective permeability are simultaneously negative over a restricted frequency range. Thus, in this frequency range such a medium is "left--handed", and is characterized by a negative refractive index. In this paper we study the scattering of p-and s-polarized electromagnetic waves from, and their transmission through, a slab of a left--handed medium whose illuminated surface is a one-dimensional randomly rough surface. We assume that the surface profile function is a single-valued function of the coordinate in the mean plane of the surface that is normal to its grooves and ridges, and constitutes a zero-mean, stationary, Gaussian random process. In the frequency range we are interested in, the electric and magnetic excitations give rise to p- and s-polarized surface polaritons, Brewster modes, and waveguide modes in the slab. The reflectivity and the transmissivity of such a slab as a function of the angle of incidence displays structure associated with the existence of a Brewster angle in both polarizations and the existence of a critical angle for total internal reflection in both polarizations. The presence of surface roughness leads to a shift of the Brewster angle, the sign of which depends on the existence or nonexistence of surface or guided waves at the frequency of the incident field.

Estimating the effects of diffraction is essential in modern radiometric experiments. The majority of the tools used for this date back to the pioneering work by W. Blevin and W. Steel. These were analytical in nature, obtained by aggressive use of approximate techniques applied to the Fresnel diffraction integral; further, blackbodies were treated as uniform sources that could be described by a single characteristic wavelength, enabling diffraction effects to be determined through a single monochromatic calculation. This requires diffraction effects to change linearly with wavelength. The domain over which this is satisfied to the error tolerance required by contemporary radiometry is unclear. This paper investigates the single wavelength technique and establishes criteria for its use.

Theoretical calculations have shown that in order to obtain changes in the spectrum of light scattered from a randomly rough surface that are large enough to be observed experimentally, this spectrum should be measured at angles of scattering in the near vicinity of features in the scattering pattern whose angular positions depend strongly on the frequency of the incident light. A scattering system that possessses such features is a dielectric film deposited on the planar surface of a reflecting substrate whose illuminated surface is a 2D randomly rough surface. When the dielectric surface is weakly rough, coherent light scattered from this system consists of speckle spots that arrange themselves into concentric interference rings, called Selenyi rings, centered at the normal to the mean surfaces. The angular positions of these rings (intensity maxima) are independent of the angle of incidence of the incident light. When the dielectric surface is strongly rough the angular positions of these rings now depend on the angle of incidence, and they are called Quetelet rings. The angular positions of both types of rings depend strongly on the wavelength of the incident light. Therefore, the spectrum of the scattered light, measured at a scattering angle close to the position of one of these rings, can differ significantly from that of the incident light. In this paper we study experimentally the scattering of light from the system just described, namely a dielectric film deposited on the planar surface of a metallic substrate, when the illuminated surface of the film is a 2D randomly rough surface. We find large changes in the spectrum of the scattered light at scattering angles in the neighborhood of the fringes in the scattering pattern to which this system gives rise.

We present an experimental and theoretical study of light scattering and propagation in multimode optical fibers with rough surfaces. In the experiments, performed at λ=655 nm, we used multimode 200 μm diameter silica glass fibers with an etched rough section. As the guided light reaches the rough part of the fiber it is scattered, feeding other modes and leaking out into the surrounding space. After some distance, however, the leakage decreases and the light within the fiber is carried primarily by the modes with low transverse wavenumbers. The light then propagates with a relatively narrow (half-width of about 0.15 rad) and slowly reducing angular spread. To understand this behavior, we develop a diffusion model for the intermode power transfer. The model predicts the formation of a narrow central maximum with a stable propagating angular profile, and relates parameters of the fiber and the surface roughness to the characterstic decay lengths.

The rough surface inverse scattering problem is studied using evolutionary strategies. The objective is to reconstruct the surface profile function from far-field angle-resolved scattered intensity data. For simplicity, the random surface is assumed to be one-dimensional and perfectly conducting. The optimum of the fitness function is searched using two versions of the evolutionary strategies; the non-elitist strategy, and the elitist strategy. The search space is reduced with the assumption that the unknown surface profile constitutes a realization of a stationary zero-mean Gaussian random process with a Gaussian correlation function With the conditions and parameters employed, the surface profile can be retrieved with high degree of confidence. Issues related to the lack of uniqueness of the solution are also discussed.

In a previous investigation we have studied the excitation of a surface plasmon polariton (SPP) when a volume electromagnetic wave in the form of a beam illuminates a circularly symmetric protuberance or indentation of Gaussian form on an otherwise planar metal surface in contact with vacuum. The fraction of the incident flux that was scattered into a SPP was rather small, of the order of one percent. In this paper, we propose a different form for a circularly symmetric surface defect and show that it is possible to achieve a much higher efficiency for the excitation of a SPP. The surface profile function we employ is of cosinusoidal form along the radial coordinate up to a radius R0, and vanishes outside this radius. Here R0 is chosen such that the profile function is continuous. By exploiting the circular symmetry of the problem we expand the reduced Rayleigh equation for the p- and s-polarized components of the electromagnetic field above and on a vacuum-metal interface into a set of one-dimensional integral equations that we then solve numerically. The solution of the integral equations in the first Born approximation shows that the scattering amplitude is related to the Bragg vector of the periodic part of the surface. Thus, a specific scattering geometry can be optimized by adjusting the periodicity and consequently the Bragg vector. We report excitation efficiencies that are about 15 times larger than those achieved with a Gaussian profile.

The coherence theory predicts that the correlations in the fluctuations of a source distribution can cause frequency shifts in the spectrum of the emitted radiation, even when the source is at rest relative to the observer. In this paper the changes in the spectrum of light scattered from a randomly rough metal surface are investigated. The experimental results are compared with the results of rigorous computer simulations.

Using a scanning near-field optical microscope with a metallic probe tip, we investigate the formation of near-field optical images. The scatter-probe is used only for converting an evanescent field to a propagating field and the detection system is in the far-field. This situation models the usual experimental set up employed in scatter-probe near-field microscopy. We study a 2D model of the scattering of s-polarized light, in which the object is illuminated by total internal reflection. The calculations of the scattered intensity at constant height were based on an integral equation, method of moments approach.

As it is well known, the diffraction of p- polarized wave on metal gratings may be accompa-nied by Wood type anomalies, caused by resonance excitation of surface plasmon polaritons. In the report we present the results of the analytical and numerical investigation of the reso-nance diffraction for grazing incidence on the gratings with period larger than the wavelength. In this case a number of diffracted orders, corresponding to evanescent waves may be close to the resonance simultaneously, i.e., we have multiple resonance case. We consider the high conducting plane surface with harmonically modulated surface impedance, presenting small parameter of the theory. Contrary to the case of single or double resonance case, the infinite set of the linear algebraic equations for the diffracted wave ampli-tudes cannot be reduced to one or two equations for the resonance wave amplitudes. But for the harmonic grating, the matrix of the system is Jacobi one and thus the solution may be presented in the continued fractions form. The results are analyzed as functions of the wavelength to grating period ratio 0.1...0.0003, and grazing angle 0...30 deg. It is shown that a number of evanescent wave am-plitudes can exceed amplitude of the incident wave and possess complicated behavior as func-tion of parameters. The specular reflectivity is of complicated behavior also and in some cases it is similar to the one obtained in numerical calculations and experiments for deep profile gratings.

For the numerical prediction of the scattering behavior of arbitrary surfaces the use of a multi pole mthod is a potentially successful way. One reason is its direct addressing of the free space problem, which is primarily not possible with methods such as FEM. For purposes of verification with a reduced set of degrees of freedom the multi pole method is applied on gold plated blazed optical gratings, which are described as surfaces with one-dimensional height function and ideally conductive boundary, leading to a 2D-problem with a simplified matching of the boundary conditions. The geometry is deduced from AFM measurements, numerical results are compared with measurements. An outlook is given on further extensions of the multipole method to 3D-problems with arbitrary boundary conditions such as dielectric layers with losses.

Scatterometry is a powerful and fast measurement method to measure surfaces and its properties. The backscattered light from a coherently illuminated surface contains information about integral surface topography constants, material properties, surface defects and contamination. This paper is a continuation a previous paper. In this paper the development of the angle resolved light scatter sensor system LARISSA (Large Dynamic Range Intelligent Scatter Sensor Approach) will be reviewed. In the first part of the paper the system components will be outlined. The system consists of an elliptical mirror optics and a CMOS photodiode detector array. The elliptical mirror optics enables the angle resolved and the integral scatter measurement in a solid angle of Pi sr. The CMOS photodiode detector array consists of 32k single detector elements which are aligned in a circular form. Each single detector element is calibrated in a dynamic range of 7 decades of intensity. The ARS system can be used to realize a scatter measurements without moving parts which is a significant advantage in speed over conventional goniometer setups. In the second part of the paper typical applications will be described which were examined by using the ARS system. Thereby surface roughness measurements in a rms range of 4..32 nm on smooth metallic surfaces will be considered by using BRDF measurements and the Rayleigh-Rice theory. In the third part of the paper the theoretical performance limits of surface roughness measurement will be derived based on measurements and simulation models. Finally the development and measurement results will be summarized and further the system will be outlined.

We report the experimental results displaying the interference of light produced by a pair of symmetrical Collett-Wolf source. By applying Mach-Zehnder interferometer to a pair of symmetrical Collett-Wolf source, the temporal average over an ensemble of realizations of the output power spectrum of the interferometer will display a bright coherent line in the center, which shows the temporal coherence behavior the input beam.

The multi pole method is formulated for the problem of large, non-symmetrical surfaces, in terms of matrix operations. The numerical effort is estimated for every step of the numerical implementation, depending on the complexity parameters of the partial problem under consideration. For comparison, a special solution for cylindrical surfaces is mentioned, demonstrating a rigorous enhancement in numerical performance.

The results of bi-directional reflectance distribution function (BRDF) measurements of four tarp samples obtained from NASA’s Stennis Space Center (SSC) are presented. The measurements were performed in the Diffuser Calibration Facility (DCaF) at NASA’s Goddard Space Flight Center (GSFC). The samples are of similar material structure but different reflectance. The experimental data were obtained with a Xe arc lamp/monochromator light source as well as laser light sources in the ultraviolet, visible, and near infrared spectral regions. The BRDF data were recorded at four incident zenith angles and at five incident azimuth angles. The dependence of the measured BRDF on weave orientation was analyzed and presented. 8 degree irectional/hemispherical reflectance data were also measured for each tarp sample, and those results are also reported. All results are NIST traceable through calibrated standard plates. The specular and diffuse scatter data obtained from these studies are used by NASA’s SSC in their field-based, vicarious calibration of satellite and airborne remote sensing instruments.

Eye-safe laser radar systems based on gated viewing use narrow infrared laser pulses to illuminate a whole scene for direct (incoherent) detection. Due to the time of flight principle and a very fast shutter with precisely controlled delay time, only light reflected in a certain range slice is detected. Due to the lack of off-shelf components, the development of such systems is difficult. Also, comparison of different systems is complicated, since atmospheric transmission, target reflectivity, polarization, and different noise effects have great influence on the system performance. The laser radar equation is used to estimate range performance in a a general manner. In this paper we discuss improvements in the system modelling of our laser radar system. Pixel wise simulation in combination with three dimensional scenes, generated with Virtual Reality Markup Language (VRML) is used to generate realistic range images. Changing to a pixel oriented approach and three dimensional modelled scenes, we are now able to study the system response for targets with arbitrary form and even different reflectivity. Also, we take into account the gaussian nature of the illuminating laser spot and different noise sources. Hence it is possible to simulate gray value images and calculate range images.

Characterization of optical appearance by measurement of the hemispherical scattering distribution using a concave projection screen and a camera is investigated. Secondary intensities by repeated internal screen reflections can be measured separately and compensated for. The concept is coupled to functional properties of product surfaces and we use it in an industrial environment. Only little less accurate than a photogoniometer, the hardware is much cheaper, contains no moving parts and is up to 1000 times faster.

The paper analyzes measurement of stress by means of the method so-called speckle pattern decorrelation. This relatively new and easy realizable method for the non-contact measurement of the small deformation tensor components of an elementary area of the object surface using the statistical properties of speckle field was firstly studied by I. Yamaguchi and later by the authors of this paper, too. At first, the general description of the presented method is briefly referred and the fundamental equations are derived both for the case of optically free space and image field. Then some possible experimental arrangements for the measurement of the deformation component (specific elongation) on an investigated object rough surface are designed and analyzed from the point of view sensitivity and range of measurement. Finally, some achieved experimental results are also noticed.

This paper extends the utilization possibilities of the joint transform correlator. The principle of the correlator can be used for determination of relative translation of two mutually displaced speckle patterns. An optical processor based on this architecture is designed. Such processor could be a part of an optical system for a noncontact measurement of object translations, rotations or deformations using the speckle decorrelation method. The paper presents computer simulation of the optical processor. In addition to basic theory of the processor the description of preparation of input data for the simulation analysis is mentioned. Both short description of the computing algorithm and some obtained results of the simulation are presented, too.

We present nonperturbative results for the effective impedance of strongly inhomogeneous metals valid in the frequency region in which the local impedance (Leontovich) boundary conditions are applicable. The inhomogeneity is due to the properties of the metal and/or the surface roughness. If the surface of an inhomogeneous metal is flat, the effective surface impedance associated with the reflection of an averaged electromagnetic wave is equal to the value of the local impedance tensor averaged over the surface inhomogeneities. This result is exact within the accuracy of the Leontovich boundary conditions. As an example, we calculate the effective impedance for a flat surface with a strongly inhomogeneous periodic strip-like local surface impedance. For strongly rough surfaces a similar approach allows us to calculate the ohmic losses and the shift of the reflected wave, if we know the magnetic vector in the vicinity of the perfect conductor of the same geometry. One-dimensional rough surfaces are examined. Particular attention is paid to the influence of the evanescent waves generatedand the difference between the elements of the effective impedance tensor relating to different polarizations of the incident wave. The effective impedance tensor associated with a one-dimensional lamellar grating is calculated.