Fast (submillisecond) measurement of the complete state of polarization (SOP) of light, as determined by the four Stokes parameters, requires instruments that have no moving parts or modulators. This is accomplished by dividing the light beam, whose SOP is to be measured, into four or more beams that are intercepted by discrete (or array) photodetectors. The output electrical signals of at least four detectors (or array pixel groups) provide four linearly independent projections of the unknown Stokes vector of the incident light. This requires judicious choices of the beam splitting and polarizing optics.

The design and operation of a Mueller matrix imaging polarimeter (MMIP) are presented. The instrument is configurable to operate in transmission, reflection, retroreflection, and variable-angle scattering to make a wide variety of polarimetric measurements. The sample may be a single element such as a lens, polarizer, retarder, spatial light modulator, or beamsplitter; the tested sample may also be an entire polarization-critical optical system containing many elements. The MMIP instrument combines a dual-rotating retarder polarimeter with high-resolution imaging capacity. Well-calibrated known polarized light states are incident upon the sample and the exiting state is precisely analyzed. By measuring a series of different generated and analyzed state, the Mueller matrix can be determined. `Decomposing' the measured Mueller matrix into retardance, diattenuation, and depolarization components can give a complete description of the sample's effect on an arbitrary light state. In one system configuration, the MMIP measures the polarization of a set of ray paths through a sample. Another configuration measures the sample's point spread matrix, a Mueller matrix relating the polarization state of a point object to the distribution of intensity and polarization across the image. The MMIP instrument and measurement capabilities are described along with an assortment of previous results.

We report the high-sensitivity measurements of 2D thermal birefringence distribution in LD pumped Nd:glass (HAP4) laser under lasing at 1054 nm and non lasing conditions. The thermal birefringence was reduced under the lasing condition compared to the non lasing condition. By inserting a 90 degree(s) quartz rotator between two identically LD pumped Nd:glass rods, almost perfect birefringence compensation was achieved with very little residual birefringence. A considerable reduction of birefringence loss from over 20% before compensation to less than 1% after compensation was observed.

Measurements of low levels of strain birefringence in fused silica glass have been made using a system based on a photoelastic modulator. Measurements of sample net retardation have been made with a resolution of 0.1 nanometers. Measured values of a strain birefringence constant for fused silica are in good agreement with established data.

The retardation modulated DIC is proposed for extracting phase information from a DIC image by analyzing the partial coherent theory, which is applied to DIC image enhancement and phase information extraction.

Polarimetry will provide useful information for various application fields of remote sensing technology. In this paper, results of experimental study on polarimetric characteristics of metallic powders, rocky powders including lunar regolith simulant and volcanic ash are presented. It was clarified that the polarimetry is useful for characterization of various terrestrial materials and for remote sensing of the Earth and planets.

We present a novel technique to measure both linear and circular birefringence, simultaneously. This technique is based on an optical heterodyne interferometry which is performed by an orthogonally polarized two frequency laser. Two orthogonal components of the optical beat signal are detected by two-phase lock-in amplifier. The two components change sinusoidally with the rotation of azimuth angle of polarization devices. The retardation and the orientation of linear birefringence and the rotation angle of circular birefringence can be calculated by applying a Fourier analysis to the two sinusoidal variations. The measurement sensitivity for this method is verified by using the combination of a Babinet Soleil compensator and a half-wave plate as a sample. It is demonstrated that the birefringence of commercially available twisted nematic liquid crystal cell where a driving voltage is applied can be measured by using the proposed technique.

The photo-elastic fringe pattern measurement technique is a nondestructive method widely used to measure the mechanical stress distribution inside solid materials. The mechanical stress distribution is evaluated by generating the photo-elastic fringe pattern and counting the number of isochromatic fringes (dark lines). If the amount of the mechanical stress is very small, however, and the corresponding birefringence is smaller than t radians, no fringe lines are produced. This method is, therefore, not suitable when the amount of the mechanical stress is small. Furthermore, ii the azimuth angle of the mechanical stress is to be measured, the sample needs to be rotated. We therefore developed a highly sensitive measurement system suitable for measuring birefringence distributions smaller than 7r radians by using an electro-optical phase modulator (Pockels cell) and a two-dimensional lock-in amplifier.1 This system can also measure the azimuth angle simultaneously without rotating the sample. Here we report the principle of this two-dimensional measurement system and give the results of measuring the 2-D birefringence distribution in PMMA fixed beam.

A visualization and quantification technique for dynamic surface charge distribution on a dielectric material has been developed based on electro-optic Pockels effect. 2 Using this technique, the surface charge density and distribution can be measured simultaneously, non-contact and non-destructively. Also by using a high-speed video camera(HVC), the dynamic observation of surface charge distribution can be performed. The measurement sensitivity is further improved by optical phase pulse modulation and the cancellation ofthe natural birefringence distribution due to the residual mechanical stress in optical devices, e.g., optical lens. As an example, the dynamic observation of surface charge distribution was performed when ac 8kV high voltage was applied to a needle electrode set perpendicularly on a Bii2SiO2o(BSO) single crystal.

Epoxy resin has been widely used as a molded insulation in electrical products. During the curing process, epoxy resin shrinks and results in an internal mechanical stress distribution inside the epoxy material. Under the operation condition, the composite stress ofboth the mechanical stress and the electrical stress may result in cracks inside the electrical unit and finally lead to the failure of the electrical insulation. Therefore, it is important to investigate the internal stress distribution. Recently a highly sensitive birefnngence measurement system, which is able to measure a small amount of optical phase retardation much smaller than 7t rad, has been developed by using an electro-optic phase modulator (OPM) and a lock-in amplifier. Both the magnitude and direction of the internal stress is measured without rotating the sample. The dynamic variation of the internal stress distribution in the curing process of epoxy resin is measured for 20 hours immediately after epoxy resin is put into a casting model.

A simple technique of measuring the polar magneto-optical Kerr effect using a rotating analyzer is developed. The technique of the rotating analyzer ellipsometer is adopted for the measurement of polarization state of light. The light intensities are digitized automatically by the simple system consisted of an analog-to-digital converter and a micro-encoder and then Fourier transformed. The expressions of rotation angle (theta) and ellipticity angle (epsilon) are obtained in terms of the Fourier coefficients of the light intensity versus rotating analyzer. This technique is applied to (theta) and (epsilon) measurement of Co/Pt films. The precision of 0.01 degree(s) in angle measurement is verified.

Acousto-Optic Tunable Filter (AOTF) is a solid state electro-optical device which acts as an electronically tunable spectral filer. The specific point on the device is that we can get two diffracted beams perpendicularly polarized each other. So we developed an imaging spectro- polarimeter employing a visible AOTF and two CCD cameras each of which shows horizontally or vertically polarized spectral image of the object. Typical specifications of the visible AOTF imaging spectro-polarimeter completed are Spectral Range: 450 - 700 nm, Spectral Resolution: 1.2 - 1.9 nm, Spatial Resolution: 20 line pairs/mm (MTF: 0.3), Diffraction Efficiency: over 90%.

The depolarization of light in diffused medium was studied by observation of temporal profiles of orthogonally polarized components. The time dependence of depolarization of light in diffused medium was simulated by using the Monte Carlo method. The projection data of absorbers hidden in highly scattering medium were taken by the method for detecting photons which preserved initial polarization using a phase modulator. The floor level due to diffused light was significantly suppressed by our method. The reconstructed optical CT image exhibited high spatial resolution in comparison with the image from the projection data taken by a conventional method.

An automatic rapid elongation system for polymer films is provided in the optical birefringence measurement system using phase modulation technology. It can measure optically and dynamically modular deformation in polymer films during rapid elongation process and stress relaxation after the completion of elongation. Micro and macroscopic information on the deformation in molecules of polymer films can be obtained by measuring birefringence retardation, stress and elastic modulus as the function of time, temperature and percentage of elongation. Advantages, details of the system and some data obtained are described.

A polarization property of a laser output was characterized for a CO₂ laser with a mirror of anisotropic reflectivity for p and s polarization installed within the cavity. A slight difference of reflectivity of the mirror for p and s polarization is emphasized through the multiple reflection within the laser cavity, because a laser system forms a feedback system to reach a laser oscillation. By using this idea of feedback system, a laser output with a linear polarization of a large polarization ratio and with a specially polarized mode like TE₀₁ which has a polarization vector tangential to a circle was obtained. A new type of measuring system is proposed to measure the polarization characteristics of the reflectivity of a mirror like sample set within a laser cavity through a laser output.

We investigated exciton-Zeeman splitting and carrier-spin relaxation in Zn_xCd_1-xSe/ZnSe multi-quantum wells using magnetic circular dichroic (MCD) measurements and photoluminescence polarization (PLP) spectra. We obtained the exciton-g value from the exciton-Zeeman splitting in the MCD spectra. The well width and Cd composition measurements indicate the possibility of controlling the exciton-g value in a nonmagnetic II-VI compound system. We observed the polarization of the higher exciton levels in the PLP spectra as a result of carrier- spin relaxation. The light hole excitons with positive polarization were affected by the strain induced by the Cd composition in the well layer.

In the extreme ultraviolet (EUV) region, synthetic multilayer structures are found useful as reflection polarizers. Such structures of transmission type made by removing from substrates are found useful as polarizers and phase shifters. With these multilayer polarizing elements developed, the first thin ellipsometry was performed at a photon energy of 97 eV (12.8 nm in wavelength), which demonstrated atomic sensitivity of the EUV ellipsometry.

Mo/Si transmission multilayers are studied theoretically for use as a polarizer at 80 eV. A multilayer of 99% polarization with a maximum transmittance of 8% was obtained by optimizing the thickness of Mo and Si. It is shown that the multilayer may be also used as a quarter-wave-plate. A new and reliable method of mounting free-standing multilayers is developed.

Analytical geometry and ray tracing are used to determine the calibration matrix A' of the four detector photopolarimeter (FDP) when the incident light beam deviates from theoptical axis of the instrument by small angles. Detectors of the FDP are represented by their surface equations in Cartesian coordinates. The field ofview (FOV) is calculated as a function ofthe light beam deviation (LBD) in two orthogonal planes, one ofwhich is the plane ofincidence for light reflection at the first detector.

Measurement and analysis of birefringence distribution in samples such as silicon wafers, electro-optic crystals and some biological specimens often poses a challenging task. Most of the standard methods for photoelastic analysis are not exactly suited to testing of samples having microscopic dimensions. The present paper proposes an interference microscopic technique where, unlike conventional interference microscopy, both the interference beams are derived from the light transmitted through the sample. As a consequence of this, the surface finish of the sample need not be of the optical order and thickness variations in the sample are not reflected in the results.

Tunable multilayer linear polarizers extend magneto-optic rotation techniques that directly sense polarization changes into the 50 - 1000 eV range. The resonant response at atomic core levels yields element-specific magnetic signals that can be much larger than the analogous signal in the visible. A tunable multilayer polarimeter is described, and examples of its use in early Kerr rotation hysteresis studies of Fe films and Fe/Cr multilayers are given.

A new type of polarizing undulator proposed and developed in the Electrotechnical Laboratory which produces high brilliant, quasi-monochromatic, wavelength-variable from the soft x-ray to infrared region, and polarized synchrotron radiation of any ellipticity was installed in the electron storage ring TERAS and NIJI-II. The synchrotron radiations emitted from these polarizing undulators were used for various research fields. In this review we report the radiation properties of the polarizing undulator, the development of magnetic circular dichroism instrument in VUV region for magnetic materials, the development of polarizing microscope for circular differential imaging, the absolute asymmetric synthesis study, and the others.

We have measured the polarization degree of the B 1s exciton emission from h-BN under resonance excitation using a multilayer rotating analyzer. We used a Mo/C 101 layers in total as a soft x-ray polarizer. The emission would include the luminescence component due to the direct recombination of the core exciton and the elastic (Rayleigh) scattering of the incident light. We have found a definite contribution of the recombination luminescence to the exciton emission peak.

We have measured the Faraday effect of cobalt polycrystalline foil near cobalt K-absorption edge with the energy-tunable x-ray polarimeter. The Kramers-Kronig (K-K) relation between spectrum of the Faraday rotation and magnetic circular dichroism measured by using the ellipticity polarized synchrotron x-radiation has been confirmed. Furthermore, we have constructed, a new type of x-ray polarimeter with a diamond phase retarder and measured x-ray linear dichroism (LD) and linear birefringence (LB) simultaneously using an hcp cobalt single crystal foil. The K-K relation between LD and LB has also been confirmed clearly.

We have developed semi-transparent multilayer polarizers for polarimetry or ellipsometry in the soft x-ray region. We have studied the fabrication processes to achieve a flat and smooth freestanding reflection surface for high-performance semi-transparent multilayer beam-splitters, mainly the stress control of Mo/Si multilayer films and the surface roughness of the support membrane. In this work, we verified that these processes can be applicable to fabricate not only beam-splitters but also polarizers with high reproducibility. The flatness of 1.1 nm (rms) was obtained in the active area of a 11 mm square semi-transparent multilayer polarizer. The measured reflectivity and transmittance rates for s-polarization using synchrotron radiation were 45.3% and 5.6%, respectively, at a wavelength of 13.9 nm. We estimated the polarization characteristics by calculating its relative reflectivity, relative transmittance and phase shift for polarization experiments. As a result of the calculation, we verified that the fabricated semi-transparent multilayer polarizers can be adequately used as a polarizer with polarizance of 69.5% and high throughput of 28.9%, or as a phase shifter of 68 degrees with equal transmission ratio and high throughput of 4.9% for x-ray polarimetry or ellipsometry.

In the application of fiber optic polarimetric sensors two major problems occur: (1) the influence of the connecting fibers and (2) the influence of internal birefringence in the sensing area which has not to be constant over its whole length. In the following paper we describe a method which overcomes these problems by analyzing the polarization transfer matrix of the sensor element and we show the results for a fiber optic polarimetric current sensor.

The manufacturing of x-ray multilayers calls for a precise control of layers having individual thicknesses in the nanometer range and with minimum diffusion at the interfaces. Visible light kinetic ellipsometry and grazing incidence hard x-ray reflectometry (8 keV) have been used under a plasma sputtering environment. The growth of W/Si multilayers illustrates the capabilities of both methods. Thickness, density and roughness values have been derived for each layer by simulation of the experimental data. Those values fit very well the grazing x-ray reflectivity data obtained on the final multilayer exposed to the atmosphere, except for the last 2 layers as a result of oxidation.

A fast and accurate birefringence measurement system has been built to study the in-plane birefringence of a rotating optical disk substrate. The fully automated instrument incorporates an axial Zeeman laser which emits both right and left hand circularly polarized lights, stationary polarization elements and a lock-in amplifier. Measurement results showing the accurate and fast features on the system are presented. It is also demonstrated that the in-plane birefringence mapping in rotating substrate of optical disk can be obtained by use of the ability of fast birefringence measurement.

An optical heterodyne interferometer that uses various laser beams was constructed using two acousto-optic tunable filters with slightly different frequencies of the diffracted light. A film thickness and refractive index of a SiO₂ thin-film on the Si substrate were measured by varying the wavelength using this apparatus.

An optical heterodyne polarimeter operating with spatiotemporal carrier frequencies is presented for contour mapping of dynamic principal stress distributions in an epoxy photoelastic sample. Introducing of the spatiotemporad carrier frequencies causes the temporal and spatial resolutions to be fairly improved in the mapping of the stress distributions. The major functional scheme of the polarimeter is illustrated in Fig. 1. A circularly polarized beam of light transmitted by the loaded photoelastic sample turns into an elliptically polarized signal beam, which is photomixed with a local oscillator beam consisting of orthogonal linearly polarized two-frequency components. At every pixel of the arrayed photodetector, the elliptically polarized signal beam is decomposed into orthogonal linearly polarized components to be interfered, respectively, with the counterpart v1 and UT components of the local oscillator beam. Since both the z' and z'2' components are tilted in wavefront at different angles to the signal beam, the resultant photourrentgenerated at every pixel involves two beat-components at different spatiotemporal carrier frequencies. The two beat-components can be filtered in the spatiotemporal frequency domain to irovicle significant information for mapping the principal stress distribution. The combination of the spatial and temporal carrier frequencies is capable of broadening the bandwidths in the spatial and temporal frequency domain compared with.those using only the spatial or temporal carrier frequencies [1]. The spatial and temporal bandwidths of the present polarimeter are found to be both approximately three times as wide as those of the previously reported optical heterodyne polarimeters [2,3]. Experimental demonstration was carried out using a Mach-Zehnder type optical heterodyne interferometer. The temporal and spatial bandwidths of the MOS type arrayed photodetector were set at 1033 Hz and 10 mm1 ,respectively, and.the temporal and spatial bandwidths for filtering were set at 500 Hz and 5 mm1, respectively. Under these conditions, the temporal and spatial bandwidths were 1 ms and 0.1 mm for mapping of the stress distributions. A sample plate of epoxy with a circular hole of 1.5 mm in diameter was used for the experiment. The top and bottom ends of the plate were supported, and an increasing force was applied from the left to the hole. The contour mapped resuits of the spatiotemporal stress distributions ar shown in Fig. 2. The first trace is the azimuth x ofthe principal stress a, and the second and third traces are the magnitudes of the orthogonal principal stresses o and a, respectively. The spacing of two successive contours of the azimuth is 15°, and that of the magnitudes is 2.0 x iO N/rn2. The tensile and compressive stresses are indicated, respectively, by positive and negative signs. As can be seen froth the figure, o. is tensile at the left of the hole, whereas 0qiscompressive at the right of the hole. The gradients of the principal stresses increase with time.

A dual-beam differential laser Doppler interferometer system was developed. This newly developed differential laser Doppler interferometer uses either a He-Ne laser or a wavefront corrected diode laser as the light source. The circular polarization interferometer configuration adopted provides us with an opportunity to remove the acoustic optical modulator (AOM) typically used in the Doppler system for directional ambiguity removal. The removal of the AOM significantly reduces the size of the interferometer and avoids the EMI effect induced by the high frequency driving signal of the AOM. A new signal decoding algorithm was also developed to compensate for the imperfect quadrature signals. That is, even when the two signals obtained from the circular polarization interferometer are not exactly 90 degrees out of phase and are not equal in amplitude, the signal decoding can still progress as if the two signals form perfect quadratures. Also, our newly developed signal decoding algorithm can remove noise efficiently and can provide us with a displacement resolution as high as a few nanometers. The 20 MHz bandwidth achieved in this system is approximately 50 times wider than the best commercially available Doppler interferometer. In addition, both velocity and displacement can be measured by this newly developed differential laser Doppler interferometer.

A novel transmission ellipsometric measurement method with the component under test inside an active laser is presented. Analyzing frequency and polarization property of the laser radiation we can detect five ellipsometric parameters of the component under test. For the first time it is possible to distinguish between reciprocal and nonreciprocal optical rotation. The polarization properties of the laser are changed in a defined manner by two novel optical modulators. Our experiments using a diode-pumped Nd:YAG laser demonstrate the high accuracy and the short measurement time of the measurement method.

LCD production requires the deposition of complex multilayer systems on large area glass panels. The control of the different steps of the process must be made as accurately as possible not only in term of layer thickness but also in term of layer quality in some cases. The multilayer monitor especially developed by SOPRA for flat panel display (MLLM- FPDD) will be described in details in the proposed paper. The instrument is based on spectroscopic ellipsometry which is a non destructive technique. The rear face contribution is mechanically removed and no preparation of the screens is needed. We can determined not only the optical indices of the layers (scanning mode) but also can make rapidly mapping measurement on the entire surface of the panels to control the homogeneity of the layer and the run to run stability. Practical examples obtained in the field of LCD technology will be described and discussed including throughput for nine points and six parameters on patterned panels.

A four gun magnetron sputter deposition chamber equipped with in-situ spectroscopic ellipsometry is described, and the results of precisely controlled multilayered metallic and dielectric materials are reported. These structures have applications in magneto-optic memories, as well as giant magneto resistance and spin-valve magnetic read-heads.

Information about the polarization state of light beam is of interest inmany areas. Several kinds of polarization analyzers have been already developed and commercially available. However most of themrequire an optical fiber to couple a laser beam into the analyzer. We have developed acompact polarization analyzer composed of a separated optical head and a personal computer. The optical head which is very thin and compact enables in-situ measurement of the polarization state of a free-space lightwave. This isimportant to study the polarization characteristics of optical devices, because the desired polarization informationmay be disturbed and/or loosen when a light beam is coupled to the head by using an optical fiber.

The extinction ratio ER and the reflectance, or throughput, for the unextinguished s polarization R_s are calculated for infrared reflection polarizers that consist of a low- index transparent layer embedded in a high-index transparent substrate. Iso-ER and iso-R_s contours illustrate the dependence of the ER and R_s for a specific IR polarizer on the depth and width of a buried layer of SiO₂ in Si at 3.5-micrometers wavelength and 80 degree(s) angle of incidence. Both cases of a uniform layer with sharp boundaries and a diffuse Gaussian layer are considered. The diffuse-layer model employs Bruggeman's effective medium theory and is intended to simulate devices that are fabricated by the oxygen-ion implantation of Si. The angular and wavelength sensitivities of these polarizers are determined.

This paper describes the division-of-amplitude photopolarimeter, DOAP, which measures the complete polarization state of light at rates up to 2 KHz and is being developed for measurement rates up to 2 MHz. Application of the DOAP for fast ellipsometry and for Mueller-matrix ellipsometry is also described. Example results from fast ellipsometry during pulse heating experiments are given. Mueller-matrix ellipsometry using rotating quarter wave retarders and liquid crystal phase retarders is presented along with recent results.

Although there has beei considerable studies on polarized light scattered by metallic rough surfaces [1—4}, little is done al)out the 1)elIavior of phase retardation between the sand p-polarized component waves of scattered light. This paper presents an experimental study on phase retardation of light scattered by one-dimensional metallic rough surfaces

Such small birefringence is a serious problem for laser quality as is caused by thermal stress or residual stress in laser material. Its distribution has to be checked for manufacturing process. It is necessary for the birefringence measurement to determine the relative retardation as well as the azimuthal angle of the fast axis in an optical sample. Up to now there are some reports, but in these methods one point measurement is performed. Here a 2D birefringence measurement method is proposed using phase shifting techniques. Its accuracy is not only high enough but also high enough in speed to detect thermal effect. Eight or sixteen images are available to measure the birefringence distribution using two phase shifters such as a half-wave plate and a Babinet-Soleil compensator. This method can measure 256 X 256 values of the birefringence in short time with around 1 deg of the resolution. The minimum detectable limit is 0.02 deg by using local-sampling phase shifting technique.

In this paper, vibration detection by an optical interferometer based on self-diffraction of photorefractive two-wave mixing is described. Sensitivity of this optical interferometer using Cu doped KNSBN crystal and a He-Ne laser at 632.8 nm depends on vibration amplitude and polarization angle of incident beams. Both effects of vibration amplitude and polarization angle are researched theoretically and experimentally. Each experimental result agrees well with theoretical result.

We have equipped an ion assisted deposition system with a rotating-analyzer ellipsometer (RAE) for in-situ monitoring of the deposition process. We propose the optimum conditions for the SiO₂/Si substrate system for observation of growth processes of Au film deposition. The deposition of Au films on optimized silicon oxide substrates was observed in- situ using the RAE. The growth curves for Au films were different from those for continuous layer growth in the initial stage. The critical thickness at which the growth became continuous layer growth varied with the irradiated current density of Ar ions. The ion-current density for the minimum critical thickness of Au films has an optimum value of around 100 (mu) A/cm². The initial stage of Au growth before continuous layer growth occurred was analyzed using the Maxwell-Garnett theory and semi-quantitative agreement was obtained between the experimental and calculated results.

In our contribution we describe a novel application of reflection ellipsometry to surface measurement. Not only the refractive index of the surface material but also the deterministic surface structure is concluded from the ellipsometric parameters (Delta) , (Psi) , and p. To achieve this, we here proposed two novel procedures: (1) the ellipsometric differential topometry and (2) the ellipsometric reference film method. The required measurement setup is described. To measure the ellipsometric parameters we developed a novel measurement procedure. Results of preliminary experiments are presented.

We are reporting about a novel ellipsometric measurement procedure which enables us to detect forces and force- related sizes at high resolution by use of the laserinternal photoelastic effect. The measurement procedure is based on the intracavity transmission ellipsometry developed by us. Relative retardation (Delta) and orientation of the main axis p of the component under test can be concluded from the polarization state and from the beat frequency of the orthogonally polarized modes of an active laser. Our measurements of weight forces show a very good linearity in a measurement range of seven decades. The Nd:YAG-laser technology enables us to develop very small sensors at high accuracy.

Polarization modulated spectroellipsometer was utilized to monitor, in-situ, deposition of Ag on Si substrate. The angle of incidence was determined using a Si substrate covered with native oxide. In the wavelength region of 550 nm to 700 nm, the ambiguity of the angle of incidence was within 0.2 deg. A plasma resonance peak manifested in reflectance spectrum around 350 nm increased and shifted to shorter wavelength as the deposition time increased from 1 sec to 10 sec. (Delta) (Psi) trajectory approached to a simulation curve of a continuous film as the deposition time increased to 40 sec where the film thickness was estimated to be 20 nm.

Thin film color filters have been characterized precisely by spectroscopic ellipsometry and transmittance measurement using the new GESP5 SOPRA instrument. Ellipsometry provides precisely not only the thickness of the layers but also the optical indices of a wide wavelength range. The optical index and the absorption are determined independently to allow accurate determination of thickness and pigment concentration and save costly materials. The quality of the layers can be checked from run to run but also on the same panel making mapping measurements. The spatial resolution around 200 micrometers and precise positioning allow measurement in a single pixel. Using these structural informations the theoretical transmittance of the filters can be deduced and compared to the corresponding experimental measurements made with the same instrument.

An empirical dielectric function has been proposed for amorphous materials. This function is based on the optical absorption in the inter band region and it follows the Kramers-Kronig dispersion relation of causality. The applicability of this dielectric function was demonstrated by analyzing spectroellipsometric measurements of several amorphous materials which has different band gaps and elements. According to the experimental results, this function is much suitable in the analysis of SE data of amorphous materials.

A laser diode chip coated with thin films on both edge- facets is proposed as a main functional device for a lensless magneto-optical (MO) reading head in a new magneto- optical floppy disk system. The head consists of the laser chip with anti-reflection coats, birefringence quarter wave films (QWF), a half mirror film (HM) and a Faraday rotator thin film, a polarizing film (as a combining device for two polarized waves) and a high speed photo diode chip. They are all die-bonded on one pair of heat sink metal which also works as electrodes supplying the injection current to the laser diode chip. An aero-flow suspender keeps the optical head very close toward the floppy disk recording surface. The laser cavity is formed between HM and MO disk. In this optical head the laser can oscillates two orthogonal linearly polarized laser waves in the inside of the chip but they are converted into two circular polarized waves in the outside of the chip through the two QWFs which are coated on the two edge-facets of the laser chip. The MO signal can be got from detecting a difference frequency between the two circular polarized waves which had been biased by the Kerr effect on the surface of the disk.

Mueller matrix polarimetry has been used to determine operational efficiency and material quality in lead- lanthanum-zirconium-titanate (PLZT) electro-optic modulators. PLZT is a transparent, quadratic electro-optic ceramic which is a candidate for the next generation of electro-optic interconnects and modulating devices. The Polarimetry group at the University of Alabama in Huntsville has measured Mueller matrices for several sample devices. The purpose of this study was to evaluate the optical quality of the transmissive PLZT devices, determine the uniformity of the modulation across the active area, and calculate the quadratic electro-optic coefficients. High- resolution imaging polarimetry has demonstrated the uniformity of the polarizing and polarization-scrambling properties of a bulk PLZT spatial light modulator array. The Mueller Matrix Imaging Polarimeter was used to produce magnified maps of device regions; this data provides insight to the material uniformity, proper contact of drive electrodes, distribution of the applied electric fields, and quality of the surface. Light scattering from ceramic grain boundaries was also observed to result in some depolarization of light exiting the device. A single-channel Mueller matrix polarimeter measured spatially-averaged device performance for a range of applied operating voltages. This information easily determined the electro- optic coefficients for the modulating material. Several chemical vapor deposited thin-film PLZT devices were studied, and the quadratic electro-optic coefficients compared favorably to that for bulk PLZT.

The liquid crystal display industry relies on low cost high performance polarizers. In this paper we will describe a novel reflective polarizer, based on a special cholesteric liquid crystal (CLC) blend which results in a single layer polarizer having a super broad band approaching 2,000 nm. The novel polarizer overcomes many of the limitations of the conventional dichroic polarizers. It also improves the band width of prior art CLC polarizer invented by Phillips. While the latter relies on creating a linear pitch gradient and requires a special UV dye to obtain the broadband polarizer. Reveo's invention, in contrast, eliminates the need for special UV dye and uses a non-linear pitch distribution to create a band pass of about 2,000 nm in a film thickness of 20 microns.

Meadowlark Optics has developed a variety of spatial light modulators (SLMs) for nondisplay applications. They operate by electrical control of the birefringence of nematic liquid crystals to achieve spatial and temporal modulation of phase and amplitude of light. They modulate phase by electrically varying the effective extraordinary index, n, of a uniaxial layer of nematic liquid crystal. This varies the optical thickness of the layer for light that is linearly polarized parallel to the optic axis of the layer. The SLM's can modulate amplitude for light that is linearly polarized at 45° to this direction if they are followed by an orthogonal or parallel linear polarizer.

The National Institute of Standards and Technology is developing a quarterwave linear retarder for operation at 1.3 micrometers . It is expected to be stable to within +/- 0.1 degree(s) over practical ranges of wavelength, temperature, and incidence angle. A spectral range of at least 10 nm is desired to accommodate solid-state and diode laser sources and typical wavelength variation. Normal incidence operation with an angular tolerance of +/- 1 degree(s) allows alignment by retroreflection of a collimated input beam. Operation over a temperature range of 25 +/- 10 degree(s)C encompasses most laboratory conditions, and practical rates of temperature change must also be allowed.

Recording and readout properties of PRIZ spatial light modulator in photorefractive Bi₁₂SiO₂₀ crystal have been investigated. Modulation efficiency of polarization of read out beam with the modulator via electro-optic effect is theoretically estimated by the effective electro-optic coefficient. By using the modulation efficiency, the spatial differentiation of input patterns along a selected direction can be carried out experimentally in real time.

Obliquely vapor deposited thin film (OVD-TF) is characterized by its unique inclined columnar structure (ICS). In previous work, the form birefringence originated from ICS was utilized to form amorphous Ta₂O₅ thin film retardation plates (TF-RPs). By reducing the size of ICS in nm scale range, the film was durable and transparent getting rid of the haze inherent in usual OVD-TF. In the present work, again TF-RPs were formed on fused silica substrates but this time by simultaneous oblique deposition from two Ta₂O₅ sputtering sources located at opposite azimuthal directions in a specially designed sputter-deposition apparatus. A typical birefringence obtained was (Delta) n equals 0.087, 0.049 and 0.043 at the wavelength of 300 nm, 500 nm and 800 nm, respectively. A film of 2550 nm thick can make a quarter wave plate at 500 nm. The columnar structure which inclined no more this time does not cause birefringence for a normally incident light. The birefringence comes this time from the fact that the columns are less closely spaced in the plane of the vapor incidence (PVI) than normal to PVI. This is the first example that the birefringence of this type is utilized to fabricate TF-RPs. The growth mechanism of this anisotropic nm scale structure was discussed with 3D-simulation of ballistic deposition.

A broadband quarter-wave plate of subwavelength lamellar grating has been designed by an optimizing method using the effective medium theory and the rigorous couple wave analysis. The phase retardation can be maintained at 90 degree(s) by strong dispersion of the propagation constant in the periodic structure. Before optimizing the grating profile by the rigorous analysis, the profile is roughly estimated with the effective medium theory. After the rough estimation, the close profile is determined by the steepest descent method using the rigorous analysis. The optimized quarter wave plate keeps the retardation at 90 degree(s) with errors smaller than 1 degree(s) for the +/- 10% change in wavelength from the nominal wavelength. Also tolerances of fabrication errors are discussed.

Optical nonlinearity is a very important and useful phenomenon for frequency up-conversion of laser beams and for heterodyne demodulation due to mixing of optical signals, which will be realized by high quality crystals with large conversion efficiency. Since one of the candidates is BBO (beta-BaB₂O₄) crystals, the light scattering from the crystals was detected by two vidicon systems under an IR laser beam scanning. Here, one of the systems is used for detection of the scattered IR rays due to defects and the other for the visible light, both of which will simultaneously acquire the scattered light intensities from the crystal.

In this research, the structural and electronic properties of a modulation-doped n-Al_xGa_1-xAs/GaAs heterostructure was nondestructively studied using spectroscopic ellipsometry (SE) and photoreflectance (PR). Se was used to characterize the thickness and Al composition x of the Al_xGa_1-xAs layer for the given sample. On the other hand, PR was used to determine the surface built-in electric field strength and the bandgap energy of the Al_xGa_1-xAs layer. The results of our analysis show that SE and PR, being complementary to each other, are useful methods in characterizing the given sample.

We have developed a new experimental equipment for the ellipsometric study of a physisorption system on a surface of a metal single crystal; a vacuum chamber with an ultimate pressure of 10^-9 Pa, a substrate temperature between 40 K and 1000 K, and the automatic null ellipsometer. The adsorption isotherms of Xe/Ag(111) at temperatures between 60 K and 80 K were obtained in the wide pressure range between 10^-7 Pa and 10^-1 Pa. We found that this ellipsometer made it possible to observe layer growth of a van der Waals condensate from a submonolayer range to a thick layer where equilibrium pressure was nearly equal to the bulk saturation vapor pressure of the adsorbate.

Titanium dioxide films prepared by a conventional electron beam deposition, an ion assisted deposition (IAD) and a radio frequency (RF) sputtering deposition is studied, where optical methods of transmission, spectroscopic ellipsometry (SE) and a quantum mechanical dispersion relation are involved. The complex dielectric function of TiO₂ in film phase at the spectral range from 1.5 eV to 6.5 eV is obtained for the use of the reference data. From the SE analysis, it is found that IAD grown TiO₂ films and RF sputter grown TiO₂ films have lower void fraction (5 - 14%) compared to the conventional electron beam grown ones (19 - 24%). As the film thickness increases from 500 angstroms to 3200 angstroms, the packing density of TiO₂ films monotonically rises from 87% to 95% when prepared on c-Si substrate, but it varies from 86% to the maximum value of 91% near 2000 angstroms when prepared on vitreous silica substrate. Surface microroughness of TiO₂ films prepared by the conventional electron beam deposition is confirmed by atomic force microscopy images.

We developed an optical birefringence measurement equipment by using a photoelastic modulator and a polarized laser. A He-Ne infrared laser is used as a light source to measure the optical birefringence in silicon wafers. We explain the theory and process of the measurement of stress in silicon wafers. The magnitude of principal stress difference and also the direction of the principal stress are obtained simultaneously and quantitatively using our experiment. The optical birefringence of (100), (111) and (110) face silicon stressed specimens were measured. From the experimental results, the photoelastic constant depends on the crystalline orientation. By the stress-strain analysis of silicon single crystal, it was found that the relation between the principal strain difference and the retardation was independent of crystalline orientation.

This paper describes a transient state of polarization in an optical ground wire (OPGW) theoretically, experimentally and with field measurements in lightning conditions, which is considered one of the fastest phenomena of polarization fluctuations in the natural environment. These characteristics will be required for optical coherent communication for utilities in future and for application to sensing of lightning with OPGW.

We have studied plasma oxidation of silicon surfaces using real-time ellipsometry. The real time observation shows a strong dependence of the plasma oxidation on the plasma density and dc bias. The results clearly reveal that the direction reaction of both positively and negatively charged species with the silicon surface dominates the plasma oxidation process in the ultra thin oxide film region. The effects of temperature and surface orientation of the substrate are also discussed.

By using a high-sensitivity high-spatial-resolution scanning infrared polariscope, we have quantitatively measured a small amount of birefringence induced by residual strain in commercial wafers of III-V compound crystals. From the measurement results in commercial (100) wafers of GaAs grown by the liquid encapsulated Czhocralski method, it is found that the 2D distribution maps of absolute difference (Delta) n between the principal refractive indices exhibit fourfold symmetry accompanying some fine structure such as stripes or line-segment patterns. The magnitude of (Delta) n is about 5 X 10^-5 in maximum and the principal axes of birefringence are approximately radially or tangentially aligned. From the detailed analysis of photoelastic effect on the (100) wafers, the in-plane components of residual strains: S_yy - S_zz and 2S_yz are deduced from the measured (Delta) n and the principal angle of birefringence (psi) .

Refractometry, linear and circular birefringence measurements, applied to transparent antiferromagnetic substances, is reviewed from a viewpoint of magnetic phase transition. A symmetry breaking birefringence observed in the ordered spin phases of a triangular lattice antiferromagnet RbFeBr₃ is discussed with respect to the spin ordering of this system. Results of verdet constant measurement are shown on a couple of typical uniaxial antiferromagnets having the CdCl₂ structure.

In this research, spectroscopic ellipsometry (SE) was used to study effects of heavy doping on the optical properties of n-type Si. The Si samples investigated were ion-implanted at 100 keV with phosphorus dose ranging from 6 X 10¹⁴ to 6 X 10¹⁶ cm^-2 and annealed using a KrF excimer laser in the nitrogen environment. SE measurements were carried out in room air, in the wavelength range from 250 to 850 nm. In the spectral analysis for each sample, a two-layer fitting model was used, in which the effects of the native oxide were included and the optical properties of ion-implanted laser-annealed Si were represented by a set of five Lorentz harmonic oscillators. Excellent agreement was obtained between the measured and calculated spectra, indicating that the model used was adequate and that the calculated results were reliable. Using the dielectric function data obtained from the model calculations, the E₁ and E₂ critical point (CP) energies were obtained by fitting the second derivative of the imaginary part of the measured dielectric function to a standard analytic lineshape, from which the doping-induced shift at the two CP's was determined.

Spectroscopic ellipsometry (SE) was used to characterized sol-gel Ba_0.7Sr_0.3TiO₃ (BST) thin films on Pt- coated Si. Four samples were investigated, each containing a sol-gel BST thin film with a nominal thickness of 200 nm deposited on Pt and annealed at 400, 500, 600 and 700 degree(s)C, respectively. In this study, our main objective was to determine the temperature-dependent optical properties of the BST thin films. In the analysis of the measured spectra, two fitting models were used, one containing a BST film and another containing a surface roughness layer and a BST film. The optical properties of BST film in both models were represented by a Cauchy's function. Our SE analysis clearly shows that the refractive index increases with the increase of the annealing temperature, which, we believe, is an indication of further crystallization of BST thin film. In addition, we also determined the BST film thickness for each sample and found it decreasing with the increase of the annealing temperature.

Direct bandgap In_xGa_1-xP/GaAs heterostructure has received increased attention as an alternative to Al_yGa_1-yAs/GaAs system, due to the attractive properties of In_xGa_1-xP, e.g., it is lattice- matched to GaAs and is more superior to Al_yGa_1-yAs in terms of number of deep level traps and susceptibility of surface oxidation. For the fundamental and applied purposes, knowledge of anisotropic effect on the optical properties of In_xGa_1-xP is often important. Spectroscopic ellipsometry (SE) is known as a sensitive optical tool for nondestructive characterization of semiconductor materials. In this research, SE was used to investigate anisotropic effect on the optical properties of In_xGa_1-xP. Each of the two samples used contained an undoped and ordered (100) In_0.48Ga_0.52P thin layer grown on a semi-insulating (100) GaAs substrate by metal-organic chemical vapor deposition. SE measurements were carried out in room-air with the sample cross-sections [011] and [-011] oriented parallel to the normal of the incidence plane, respectively. In the data analysis, the optical properties of In_xGa_1-xP were extracted via a fitting model which included the effects of the native oxide overlayer. We determined the critical point (CP) energies of In_xGa_1-xP by fitting the second derivative of the measured dielectric function spectra to a standard analytic lineshape. For each sample studied, our results clearly show a shift in energy for each chosen CP, when the sample cross sections [011] and [-011] were oriented parallel to the normal of the incidence plane, respectively. We believe that this shift is directly related to the anisotropic effect on the optical properties of In_xGa_1-xP.

Photoellipsometry (PE), a contactless optical method, combines the features of both spectroscopic ellipsometry and photoreflectance (PR) and offers more complete information about the sample from a single experiment. PR, on the other hand, has been widely used for characterizing semiconductor microstructures. The nondestructive nature and the relatively sharper features produced in the measured spectra make this method very attractive. It was based on these advantages that we applied PE and PR to Si (delta) -doped GaAs. Two Si (delta) -doped GaAs samples were investigated in this study, each having an undoped GaAs cap layer of thickness (L equals 100 and 200 nm, respectively). Our main objective was to determine built-in electric field strength in the cap layer of each sample. In the analysis of the measured PE spectra, the Franz-Keldysh (FK) theory was used, taking into account the broadening and the photovoltage effects, whereas the measured PR spectra were analyzed using the asymptotic form of an Airy function for the FK oscillations. The results of our analysis show that, for each sample studied, the field strength obtained from PE spectra is in good agreement with that determined from PR spectra, and that the field strength decreases with the increase of the cap layer thickness.

The process of photo-stimulated dissolution of Ag atom/ion into amorphous chalcogenide materials As₂S₃ was observed in-situ by ellipsometry. The sample was Ag/As₂S₃ film system which was deposited onto the glass substrate. The photodoping was proceeded by the irradiation of the light of 546:1 nm. Obtained values of ellipsometric parameters (Psi) and (Delta) were fitted by using a multilayer model. Time dependent changes of each thickness of Ag, Ag:As₂S₃ and As₂S₃ layers during the diffusion process were derived. These behaviors will be explained in relation with photodoping mechanism.

Spectroellipsometric characterization of SIMOX (Si, Separated by IMplanted OXygen) with very thin top Si layer is presented. The measured spectra of (Psi) and (Delta) were analyzed with the model Air/SiO₂/top-Si/embedded SiO₂/c-Si, and are explained well by the use of the established table values of dielectric constants < (epsilon) > of Si and SiO₂ and taking account of the thickness fluctuation in the embedded SiO₂ layer with an appropriate thickness distribution function. Model dielectric functions are also applied to < (epsilon) > of the top Si layer to detect the size effect. It was found that the < (epsilon) > of top Si layer with thickness down to 4.3 nm is exactly the same as that of the single crystal silicon.

Sulphur passivation of InAs is studied by spectroscopic ellipsometry. Time dependence of (Psi) and (Delta) of InAs surface after etching as well as after sulphur passivation has been measured in air. The empirical dielectric function for amorphous material proposed in the previous paper has been applied to the surface. Differences between dielectric function and thickness of surface layers with and without passivation and their time dependence after each treatment have clearly been observed.

We studied the polarization effect of the normal cornea by using birefringent special samples (PMMA) which produce polarized pattern similar to those of the in vivo cornea. The observation confirmed the change of polarization patterns in vivo cornea as a function of thickness and optical birefringence of the cornea. We posit that the hyperbolic polarized pattern seen in vivo normal cornea is the change of birefringence in the whole cornea is affected by the external oblique direction of stress, which is necessary to maintain a balanced state of the eye globe.

In this paper, different aspects of this annealing process using Single Shot high power Excimer Laser Annealing technique are examined successively. The energy density is optimized using Spectroscopic Ellipsometry technique. The crystallinity and roughness of the layers are characterized in addition to the layer thickness. The interest of large size laser beam is examined more precisely measuring the crystallinity in the transition zone between two laser shots. Finally the homogeneity of the layer is checked electrically by mapping the surface of a laser shot with TFT characteristics.

Structural and electrical quality of polysilicon layers obtained by laser annealing of amorphous silicon, is a key point for the electric properties of TFT devices. For precise optimization of the laser annealing process and on line quality control a non destructive toll capable to provide precisely at the same time the crystallinity, the thickness and the roughness of the polysilicon layers is of great interest. The paper will compare the possibilities of UV spectrometry and spectroscopic ellipsometry in the case of practical examples obtained in different conditions. The UV penetration depth of less than 20 nm investigates the channel depth of the TFT. Structural results obtained using this spectral range are then directly correlated with the mobility of the transistors. Results will be also related to Raman spectroscopy and imaging morphologies obtained by scanning microscopy. A practical procedure for using spectroscopic ellipsometry will be discussed in relation to electrical results obtained on TFT devices.

Indium tin oxide films (ITO) are characterized precisely by spectroscopic ellipsometry which determines not only the thickness of the layers but also the optical indices in a large spectral range. The quality of the ITO films is checked by the transparency of the layers in the visible range 0.4 to 0.6 micrometers . Indeed, target degradation is detected by the occurrence of an absorption band in this region. The electrical conductivity of the layer can also be deduced by the Drude model applied to the absorption in the infrared region. Moreover, spectroscopic ellipsometry can give all these information on all the surface of the panels, checking at the same time the homogeneity and the stability of the deposition process. Different experimental examples will be presented and discussed.

Liquid crystal cells with a radial molecular orientation is proposed using a UV curable liquid crystal material. A radially and homogeneously aligned LC cell (RH-LC cell) and an LC cell with a radial molecular orientation on both substrates (RR-LC cell) are fabricated and their optical properties are investigated. A polarization converting function of the RH-LC cell and detecting function of the polarization direction in the dye doped RR-LC cell are confirmed. Furthermore, an optical alignment of liquid crystal on the PVC surface is demonstrated using RH-LC cell.

For many years now, liquid crystal devices have been studied and adopted for scientific use in such areas as optical display, optical switching, variable retarders, spatial light modulators and other nonlinear optical applications. Based on the behavior of voltage driving variable retardation, we developed a liquid crystal retardation modulator with an error smaller than 0.4% and of which temperature has no effect.

Using the anomalous diffraction approximation of the light scattering theory, it was found that the circular dichroism (CD) and optical rotatory dispersion (ORD) spectra of light scattering media with large soft particles can be represented as linear combinations of CD and ORD spectra of particles' substances. The analytical formulae derived can be used for stereochemical analysis of dispersed systems.

This paper describes the experimental measurements of the optical properties ofpure liquid aluminum, zirconium, nickel and iron in the photon energy range 1 .2-3 .4 eV by pulsed-dye laser spectroscopic ellipsometry. The unique aspect of this study was the use of electromagnetic levitation to position and melt the specimens and thus eliminate any container derived impurities. This approach yielded extremely clean liquid metal surfaces on which spectroscopic ellipsometry was conducted. The complex dielectric functions were obtained on these liquids as a function of temperature and wavelength.

The paper describes the device for measuring the normal- reflection birefringence with using of the compensation method. The suggested scheme may be used for research of optical anisotropy in optical recording disks, inner stress in transparent solid body, birefringence of crystals and for the measuring of temperature, pressure, electrical and magnetic field strength.

We have developed a super high contrast polarizer (EG type). This new polarizer enhances the light transmittance of liquid crystal displays by more than 10%. We have also developed a retardation film with controlled 3D refractive index. This retardation film improves the viewing angle of LCD's.

We discuss tunable birefringent filters utilizing liquid crystals. We have incorporated nematic liquid crystals, manufactured as electrically variable, true zero-order retarders, in Lyot and Solc filter designs to allow continuous spectral tunability. The performance characteristics and design enhancements of several assembled tunable filters are discussed. These range from narrow band (0.13 nm) filters for solar imaging to wide field of view filters for airborne remote sensing spanning the spectral range 400 - 2500 nm. Design considerations for improving field of view, speed, and transmission of liquid crystal tunable filters are discussed.

By determining Stokes' parameters of light diffracted from a nematic liquid crystal grating fabricated with a grating electrode structure, polarization modulation properties of this LC grating are characterized. The electrically controllable polarization modulations of its diffracted light are demonstrated as well as its diffraction light intensity modulations. A unique property of symmetrical diffraction light intensities but antisymmetrical polarization states in corresponding negative and positive diffraction orders is shown.

The measurement of thickness of the liquid crystal layer has been done using the optical interference method with spectrophotometer up to now. But it took more than one minute to measure the thickness, and in-line measurement was impossible. So, in this paper, the measuring method of the thickness of the liquid crystal layer that it is possible to measure the thickness at high speed for about one second is proposed, and it is reported about the principle. And we report the comparison experimental results with this method and conventional method.

The final structure of the LCD devices can be extremely complex in terms of layer structure and material combination. Prior to the characterization of the entire depth of the complete screen, a precise analysis of the different layers involved in the structure is necessary. In this procedure the optical indices and thicknesses of the dielectric, ITO and complementary layers are successively determined. Final characterization of the complete device is then made possible and large gap with or without liquid crystals can be determined by the same technique. Due to the total thickness, a high spectral resolution is needed, and a spatial resolution for the measurement spot is also required to avoid lateral inhomogeneities. The index of the liquid crystal layer can finally be deduced with reasonable accuracy.

Twisted nematic liquid crystal displays (TN-LCD) are being widely adopted for personal computers. Figure 1 shows the transmittance -voltage (T-V) characteristics for the normally - white mode of a first minimum TN display. Here the polarizer transmission axis is parallel to the liquid crystal (LC) alignment direction on the adjacent substrates (e-mode TN-LCD). Figure 2 shows the viewing angles. In the lower azimuth view, the T-V curve oscillates, causing gray scale image inversion. In the upper azimuth view, the transmittance at an intermediate voltage is high and the gray scale image washes out. In the right and left azimuth view, the T-V curve is almost the same as a normal view, giving a clear gray scale image. The symmetry of viewing characteristics has been investigated 1), and light propagation in the normal direction has been calculated using a Poincaré sphere2. Light propagation for oblique viewing had not yet been examined. We investigated this using a Poincaré sphere.

Rotatable fiber loops are commonly used to change the state of polarization in fiber optic transmission systems. As an improvement of such a system we describe a feedback controlled polarization transformer which operates at its output prot as a polarization synthesizer. The whole setup allows a very efficient polarization adjustment with a stable and well known state of polarization.