Excimer laser pulses ((lambda) equals 193 nm, (lambda) equals 248 nm) induce transient and permanent defects in highly UV transparent optical glass for microlithography. Usually laser damage of fused silica is evaluated by time consuming and expensive marathon tests characterized by about 10⁹ pulses at repetition rates of 400-1000 Hz and fluences of 0.5-10 mJ/cm². Alternatively, short time tests using high laser energy densities have been developed to quickly evaluate influences of changes in the production technology. The following evaluation methods are used: Laser induced absorption at 193 nm measured by laser induced deflection (LID), Laser induced fluorescence at 650 nm (LIF) excited by 193 nm or 248 nm laser irradiation, H₂ content measurement by means of a pulsed Raman spectroscopy at 248 nm laser excitation. Both, the LIF signal and the H₂ concentration are measured locally resolved in a non-destructive way. The applied energy densities of the above methods vary from 1 mJ/cm² to 600 mJ/cm². The front face technique for investigating large diameter samples, e.g. mask blanks (6 inches and 9 inches), have been established.

We recently developed a linear birefringence measurement instrument, known as the Exicor system, using photoelastic modulator (PEM) technology. We have reported the precision and short-term stability of this instrument. In this paper, the author further evaluates the accuracy, long-term stability, and instrumental performance under low light intensity levels of the Exicor system.

We have determined the complex uniaxial dielectric tensor of bulk rutile titanium dioxide (110), (100) and (111) samples using reflection generalized ellipsometry, which measures both the diagonal and off- diagonal elements of the reflection Jones matrix. Data were acquired using three commercially available ellipsometers, each covering the following spectral ranges: 0.148 to 0.292, 0.200 to 1.7 (mu) m; and 1.7 to 33 (mu) m. Generalized ellipsometry measures three complex ratios involving all four Jones matrix elements. In principle, this means that the complex dielectric tensor of a uniaxial crystal can be determined in a single measurement, provided that the sample is oriented such that the off-diagonal components of the Jones matrix are non-zero. To improve our results, we measure the samples at several rotational orientations around the surface normal. This insures that the probing electric fields vibrate along substantially different directions with respect to the optic axis. In some cases, we also varied the angle of incidence. The dielectric tensor was determined at every wavelength directly from a simultaneous fit to data from all rotational orientations and incident angles. A similar methodology should be applicable to a wide range of anisotropic optical materials.

The temperature dependence of the absorption of the thick niobium films was measured using an AC far-infrared laser calorimeter. Moreover the temperature and frequency dependences of the absolute transmission and reflection of same thin niobium nitride films were measured from 5 to 20 K and from 10 to 200 cm^-1 using a fourier transform infrared spectrometer. The temperature dependencies of the skin depth and the absorptance determined independently by both methods are compared. However the skin depths and the absorptances agree well each other near and above T_c, they begin to deviate from each other with decreasing temperature below T_c.

A complete independent method is used to measure the infrared refractive index of sapphire as a function of temperature and frequency. The technique combines single frequency and broadband measurements. The refractive index at the wavelength 3.39 (mu) m is measured using prism and the minimum deviation method. A laser interferometer and an etalon of the material are then used to measure the thermo-optic coefficient. A broadband FTIR spectrometer is used to measure the transmittance spectrum of the etalon and then a fringe counting method is applied to obtain the frequency dependent refractive index. The technique is applied to sapphire over the temperature range from 10K to 1000K and wavelength range from 1 to 5 (mu) m. High accuracy is demonstrated. The errors of this experimental approach are analyzed.

We have performed regular spectral transmittance and reflectance measurements over the 1 (mu) m to 2.5 (mu) m wavelength region on several different types of materials using three different spectrophotometer systems. Two of the systems employ grating-based monochromators and InGaAs photovoltaic detectors. The beam at the sample position is nearly collimated. The other system uses an FTIR (Fourier Transform Infrared) spectrophometer as a source and a diffuse Au-coated integrating sphere with a photoconductive HgCdTe detector. In this system, the sample is placed at the focus of an f/6 converging beam. Measurements are performed on transmissive materials as well as either highly reflective or absorptive mirrors and the results are compared, taking into account any differences in beam geometry and polarization among the different systems.

Several peak determination algorithms are described and compared using the spectra of a NIST wavelenght/wavenumber standard reference material (SRM). These methods are the (1) centroid (or center of gravity) (with fraction value 0.5), (2) extrapolated centroid, (3) extrapolated bisecting, (4) polynomial curve fit, and (5) absolute maximum (minimum) methods. Comparisons are made of the peak wavelength value accuracy and reproducibility, versatility and other aspects of the peak determination methods. Optimization studies of the centroid, extrapolated centroid, and extrapolated bisecting peak determination methods, used for several NIST SRM's, have found that the peak value accuracy and precision can be improved by careful selection of peak fraction, spectral data density and polynomials fitting order (for extrapolated algorithms).

An optical configuration based on the photothermoplastic recording (PTPR) is suggested for the operational optical diagnostics and standardization of the products in the real time scale. The presence of three or four PTPR cameras along the counter of the tested product makes it possible to investigate in the real-time scale not only the appearance of the internal defects, but also the influence of the condition of different units onto the condition of the whole system. Dry development of the images in the real-time scale and instant fixation of images on the photothermoplastic carriers (PTPC) followed by the computer analysis used to compare the product and the standard allow us to gain in time and areas.

A goniometric system is used in conjunction with an FT-IR (Fourier- Transform Infrared) spectrophotometer to perform reflectance and transmittance measurements as a function of angle of incidence from 12$DEG to 80$DEG. The input beam is polarized using a high-quality Ge reflective Brewster-angle polarizer, and is focussed onto the sample with an approximately f/50 geometry. The average angle of incidence is controlled to within +/- 0.05$DEG, and spectra are recorded for both s- and p-polarization over a wavelength range of 1.6 (mu) m to 5.2 (mu) m, using a photoconductive InSb detector. Measurement results are compared to the predictions of the Fresnel equations in order to assess the accuracy of the instrument.

A simple, robust reflectometer, pre-set for several angles of incidence (AOI), has been designed and used for determining the optical parameters of opaque samples having a specular surface. A single, linear polarizing element permits the measurement of perpendicular(s) and parallel (p) reflectence at each AOI. The BAIRS algorithm determines the empirical optical parameters for the subject surface at the pseudo-Brewster AOI, based on the measurement of p/s at two AOI's and, in turn the optical constants n and k (or (epsilon) ₁ and (epsilon) ₂). Radiation sources in current use, are a stabilized tungsten-halide lamp or a deuterium lamp for the visible and near UV spectral regions. Silica fiber optics and lenses deliver input and output radiation from the source and to a CCD array scanned diffraction spectrometer. Results for a sample of GaAs will be presented along with a discussion of dispersion features in the optical constant spectra.

Non-destructive uniformity and defect control is an essential requirement for yield performance improvement and cost reduction of Silicon-on-Insulator (SOI) materials. To maximize performance and minimize production costs, it is critical to maintain a tight control over the oxygen implant dose. This has proven to be particularly true for the most advanced low dose SIMOX processes. Advanced FTIR reflectance spectroscopy and scatterometry have been used to characterize the buried layers of SOI materials and to relate unambiguously the process dose variations and corresponding changes of IR reflectance spectra.

An optical measurement system composed of an optical microscope (Olympus BX60) and an optical multichannel analyzer (EG&G OMA 1460) has been assembled and tested. The optical microscope allows the user to make measurements on a small and well defined area of the sample. The light source, a 100 W halogen lamp, and the diode array detector, result in high sensitivity in the wavelength region of 450-750 nm. The spectral resolution of the instrument is listed as 0.59 nm/channel. The full width at half maximum (FWHM) of the strongest peaks in calibration measurements on a mercury lamp is 5 channels corresponding to 3 nm. Quasifractal clusters of gold particles have been produced with electron beam lithography. The clusters consists of different numbers of particles, giving a cluster size variation from 1.6 (mu) m to 50 (mu) m. The individual gold particles are 50 nm in diameter each. The measurement system has been used to measure both absolute transmittance and the relative transmittance using the uncoated substrate as a reference.

Papermaking process consists in a succession of unit operations for having main objective the expression of water out of the wet paper pad. The three main stages are successively, the forming section, the press section and finally the drying section. Pressing is not on the scope of this paper but the influence of formation and drying on anisotrophy of paper properties is analyzed. More specifically, optical measurements are described in order the anisotropic structure and physical properties of paper to be analyzed.

The NRLM has developed a Fourier transform infrared spectrometer to measure spectral radiance of thermal-infrared emission near ambient temperatures with high accuracy. The spectrometer uses a simple Michelson interferometer that consists of corner cube mirrors and a KBr beam splitter. The spectral range between 5 (mu) m and 12 (mu) m was covered by a photovoltaic HgCdTe detector. For calibration and compensation for the offset drive, the spectrometer was equipped with two high quality reference blackbodies, a fixed-temperature blackbody cooled by liquid nitrogen and a variable temperature blackbody operated in the temperature range between -20$DEGC and 100$DEGC. The calibration procedure based on the advanced phase correction technique was applied to observed spectrum to complete reconstruction of the emission spectrum. Several tests were performed to check characteristics of the spectrometer. The results showed that the size-of-source effect (SSE) of the FTIR-spectrometer is negligibly small for a target larger than 20 mm diameter. We carried out an experiment to check the linearity between incident and measured spectral radiance inside the calibration levels by measuring the radiance from a third blackbody between -20$DEGC and 100$DEGC after calibration using the liquid nitrogen cooled blackbody and the fluid bath blackbody fixed at 100$DEGC. Observed non-linearity normalized at the blackbody radiance of 100$DEGC was smaller than the 0.5% around 10 (mu) m bands.

An adiabatic laser calorimeter has been developed with a sensitivity of the order of 10^-6cm^-1 with one watt of laser power using a CO₂ laser (9(mu) m to 11(mu) m) in the infrared region. The heat leak by conduction and by radiation from a sample to an inner isothermal enclosure is enough small to be ignored because we succeeded in developing the temperature tracking system between the sample and the enclosure. The total uncertainty of absorption-coefficient measurements is estimated to be 5.4%. The absorption coefficient of a potassium chloride sample #2 was (3.17+/- 0.18)X10^-3cm^-1.

A novel experimental technique for obtaining the extraordinary-ray absorption coefficient of uniaxial crystals is presented. The infrared multiphonon e-ray absorption edge of sapphire and quartz is measured as a function of frequency and temperature for the first time.

The polarization optical properties of single mode fibers are important in those applications based on the use of coherent polarized light, such as fiber optic interferometric sensors and coherent communication systems. Various birefringence mechanisms and combinations of them have been developed to control the polarization evolution of light along the fiber. Since 1977 when A.Papp and H.Harms1 suggested the application of helical core fibers for this purpose, their polarization properties have been studied by several authors.24 In I 984 J.N. Ross2 showed that helically wound monomode fibers behave as the combination of a distributed linear retarder and a distributed circular retarder. Since linear and circular retardation can be easily followed on the Poincaré sphere, this representation of polarized light results adequate for helical fibers. In this work the non-destructive evaluation of the equivalent optical activity and the equivalent linear retardation of a fiber helix are performed using the trajectory described on the Poincaré sphere when the orientation of the linearly polarized light at the input rotates 360°. The results we obtain are compared with the values determined for the linear and circular retardation using Ross model and an input circular or linear polarization. We present preliminary results obtained for the birefringence characterization of two helically wound fibers built with .-l4m and —27m of a telecommunications fiber ( I 550nm).

The comparative study of dimension distributions of ionite granules of KU-2-8, Amberlite and some other sorts by moist sizing and Mueller- polarimetry methods have been carried out. The range of particle sizes and homogeneity were measured. The experiments have shown that there exists a satisfactory agreement with the results obtained by moist sizing and Mueller-polarimetry methods. It have been shown that Mueller- polarimetry method have a high sensitivity to the granules sizing, homogeneity, shape and color characteristics of particles. The method gives the possibility to test of granulemetric composition of different sorts of ionites and can be used for testing of various kinds of synthetic adsorbents.

A new technique to obtain the real and imaginery parts of the dielectric function of an absorbing medium in terms of the ration R'_p/R'_s of the derivatives of p and s polarized light reflectances at the grazing and the normal incidence is developed. IT is shown that this ratio can be expressed through the logarithmic derivatives (1/R)R' in the vicinity of the grazing angle. The using of both the normal - incidence and near- grazing angles measurements allows to overcome the instability (extreme sensitivity to experimental error) of all inversion of the polarized reflectances methods for absorbing media. The possibility of this method is verified by the Jacobian formalism. It is important that errors in the measured parameters are not magnified when calculating the optical constants from the experimental data. We propose the practical implementation of this method with variation of the angle of incidence in an optical fashion. IT permits to perform all the measurements appreciably aside from the grazing angle and greatly enhance the accuracy of these measurements.

A laser calorimeter has been developed with a sensitivity of the order of 10^-6cm^-1 with one watt of laser power using a CO₂ laser (9(mu) m to 11(mu) m) in the infrared region. In order to evaluate the accuracy of the laser calorimeter, the absorptance of a thin and semitransparent silicon sample was measured using the laser calorimeter in the infrared region and the transmittance and the reflectance of the same sample were also measured by a conventional Fourier-transform infrared spectrometer. Two absorptances obtained from two independent methods agree will within 2%, however it becomes clear that an interval of a Fabry-Perot interference fringe doesn't agree in absorptance spectra measured by these methods.

The feasibility of an alternative surface polariton sensor is demonstrated. Existing surface plasmon resonance (SPR-) sensors use the surface of a thin metal film as detector. The critical condition for this excitation is a large negative real part of the dielectric function (epsilon) ₁((omega) ), which is characteristic for good metals in the visible and near UV range. This condition is also fulfilled in the infrared region for many compounds with partly ionic binding. Multilayer calculations are used to show that a ceramic film can be used as a sensor surface. In the calculations, the Kretschmer configuration is used to demonstrate the excitation of a surface polarion beyond the critical angle of incidence, sensitive to minute changes in refractive index near the free surface. Optimization with respect to film thickness and excitation wavelength within the Reststrahlen Band region is discussed.