Polarization observations of the unique eclipsing binary, Epsilon Aurigae, are being carried out using a new dual beam imaging polarimeter on the 0.36m telescope of the Harry D. Powell Observatory. This bright binary system has a 27.1 year period with an eclipse duration of nearly two years. The primary is known to be a pulsating F0 supergiant with the secondary a large and essentially opaque disk. We report here on the characteristics of the polarimeter and on the status of V-band observations that are being obtained to better understand the system's geometry and the nature of its two components. In particular, the characteristics of the secondary disk remain a puzzle. Results are compared to polarization observations from the 1982-1984 eclipse.

Cette thèse a été consacrée au développement et à la mise en oeuvre d’un imageur polarimétrique de Müller installé sur un colposcope standard dans le but de diagnostiquer invivo des lésions précancéreuses du col utérin.Ce travail s’est appuyé sur le développement réalisé durant les dix dernières années au LPICM à l'École polytechnique d’une nouvelle technologie d'imagerie médicale non invasive et a priori adaptée à la détection précoce du cancer : l’imagerie polarimétrique. / This thesis was devoted to the development and the implementation of a polarimetric imager of Müller installed on a standard colposcope in order to diagnose invivo precancerous lesions of the cervix.This work was based on the development carried out during the last ten years at the LPICM at the Ecole polytechnique of a new non-invasive medical imaging technology and a priori adapted to the early detection of cancer: polarimetric imaging.

The objectives of this research are to support the development of state-of-the-art methods using remotely sensed data to detect slides or anomalies in an efficient and cost-effective manner based on the use of SAR technology. Slough or slump slides are slope failures along a levee, which leave areas of the levee vulnerable to seepage and failure during high water events. This work investigates the facility of detecting the slough slides on an earthen levee with different types of polarimetric Synthetic Aperture Radar (polSAR) imagery. The source SAR imagery is fully quad-polarimetric L-band data from the NASA Jet Propulsion Laboratory’s (JPL’s) Uninhabited Aerial Vehicle Synthetic Aperture Radar (UAVSAR). The study area encompasses a portion of the levees of the lower Mississippi river, located in Mississippi, United States. The obtained classification results reveal that the polSAR data unsupervised classification with features extraction produces more appropriate results than the unsupervised classification with no features extraction. Obviously, supervised classification methods provide better classification results compared to the unsupervised methods. The anomaly identification is good with these results and was improved with the use of a majority filter. The classification accuracy is further improved with a morphology filter. The classification accuracy is significantly improved with the use of GLCM features. The classification results obtained for all three cases (magnitude, phase, and complex data), with classification accuracies for the complex data being higher, indicate that the use of synthetic aperture radar in combination with remote sensing imagery can effectively detect anomalies or slides on an earthen levee. For all the three samples it consistently shows that the accuracies for the complex data are higher when compared to those from the magnitude and phase data alone. The tests comparing complex data features to magnitude and phase data alone, and full complex data, and use of post-processing filter, all had very high accuracy. Hence we included more test samples to validate and distinguish results.

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We developed an extreme ultraviolet (EUV) polarimeter, which employs laser-generated high-order harmonics as the light source. This relatively high-flux directional EUV source has available wavelengths between 8 nm and 62 nm and easily rotatable linear polarization. The polarimeter will aid researchers at BYU in characterizing EUV thin films and improving their understanding of materials for use in EUV optics. This first-time workhorse application of laser high harmonics enables polarization-sensitive reflection measurements not previously available in the EUV. We have constructed a versatile positioning system that places harmonics on the microchannel plate detector with an accuracy of 0.3 mm, which allows a spectral resolution of about 180. We have demonstrated that reflectance as low as 0.2% can be measured at EUV wavelengths and that this data is repeatable to within the error of our source stability (~7% fluctuation). We have compared reflectance data with that taken from the same sample at Beamline 6.3.2 at the Advanced Light Source. This data agrees well from 5 degrees to 30 degrees and the angular locations of the interference fringes also agree.

Polarimetry is one of the principal means of investigating the interaction of light with matter. Theoretical models and experimental techniques are presented in this dissertation for polarimetric characterization of random electromagnetic beams and of signatures of random media in different scattering regimes and configurations. The degree of polarization rather than the full description of the state of polarization is of interest in multiple scattering and free space propagation where the statistical nature and not the deterministic component of light bears the relevant information. A new interferometric technique for determining the degree of polarization by measuring the intensity fluctuations in a Mach-Zehnder interferometric setup is developed. For this type of investigations, one also needs a light source with a controllable degree of polarization. Therefore, also based on a Mach-Zehnder interferometer, we proposed a new method for generating complex random electromagnetic beams. As a direct application of the cross-spectral density matrix formalism, it is shown that the spectral and the polarimetric characteristics of light can be controlled by adjusting the correlations between parallel components of polarization propagating through the two arms of the interferometer. When optical beams are superposed in the previous applications it is desirable to understand how their coherence and polarimetric characteristics are combined. A generalization of the interference laws of Fresnel and Arago is introduced and as a direct application, a new imaging polarimeter based on a modified Sagnac interferometer is demonstrated. The system allows full polarimetric description of complex random electromagnetic beams. In applications such as active illumination sensing or imaging through turbid media, one can control the orientation of the incident state of polarization such that, in a given coordinate system, the intensities are equal along orthogonal directions. In this situation, our novel interferometric technique has a significant advantage over standard Stokes imaging polarimetry: one needs only one image to obtain both the degree of polarization and the retardance, as opposed to at least three required in classical Stokes polarimetry. The measurement of the state of polarization is required for analyzing the polarization transfer through systems that alter it. Two innovative Mueller matrix measurement techniques are developed for characterizing scattering media, either in quasi real-time, or by detection of low level signals. As a practical aspect of Mueller polarimetry, a procedure for selecting the input Stokes vectors is proposed. The polarimetric signatures of different particulate systems are related to their structural properties and to the size distribution, shape, orientation, birefringent or dichroic properties of the particles. Various scattering regimes and different geometries are discussed for applications relevant to the biomedical field, material science, and remote sensing. The analysis is intended to elucidate practical aspects of single and multiple scattering on polydisperse systems that were not investigated before. It seems to be generally accepted that depolarization effects can only be associated to multiple scattering. It is demonstrated in this dissertation that depolarization can also be regarded as an indication of polydispersity in single scattering. In order to quantify the polarizing behavior of partially oriented cylinders, the polarization transfer for systems consisting of individual layers of partially aligned fibers with different degrees of alignment and packing fractions is also analyzed in this dissertation. It is demonstrated that a certain degree of alignment has the effect of a partial polarizer and that the efficiency of this polarizer depends on the degree of alignment and on the packing fraction of the system. In specific applications such as long range target identification, it is important to know what type of polarization is better preserved during propagation. The experimental results demonstrate that for spherical particles smaller than the wavelength of light, linear polarization is better preserved than circular polarization when light propagates through turbulent media. For large particles, the situation is reversed; circular polarization is better preserved. It is also demonstrated here that this is not necessarily true for polyhedral or cylindrical particles, which behave differently. Optical activity manifests as either circular birefringence or circular dichroism. In this dissertation, a study is presented where both the effect of optical activity and that of multiple scattering are considered. This situation is relevant for medical applications and remote sensing of biological material. It is demonstrated here that the output state of polarization strongly depends on the optical density of the scattering medium, the optical rotatory power and the amount of circular dichroism associated to the scattering medium. This study shows that in the circular birefringence case, scattering and optical activity work together in depolarizing light, while in the dichroic case the two effects compete with each other and the result is a preservation of the degree of polarization. To characterize highly diffusive media, a very simple model is developed, in which the scattering is analyzed using the Mueller matrix formalism in terms of surface and volume contributions.

京都大学 / 新制・課程博士 / 博士(理学) / 甲第24421号 / 理博第4920号 / 新制||理||1703(附属図書館) / 京都大学大学院理学研究科物理学・宇宙物理学専攻 / (主査)教授 一本 潔, 准教授 浅井 歩, 教授 横山 央明 / 学位規則第4条第1項該当 / Doctor of Science / Kyoto University / DFAM

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Accurate measurement of temperature is essential for the safe and efficient operation and control of a vast range of industrial processes. Many of these processes involve harsh environments, such as high temperature, high pressure, chemical corrosion, toxicity, strong electromagnetic interference, and high-energy radiation exposure. These extreme physical conditions often prevent conventional temperature sensors from being used or make them difficult to use. Novel sensor systems should not only provide accurate and reliable temperature measurements, but also survive the harsh environments through proper fabrication material selections and mechanical structure designs. This dissertation presents detailed research work on the design, modeling, implementation, analysis, and performance evaluation of novel optical high temperature sensors suitable for harsh environment applications. For the first time to our knowledge, an optical temperature sensor based on the broadband polarimetric differential interferometric (BPDI) technology is proposed and tested using single crystal sapphire material. With a simple mechanically structured sensing probe, in conjunction with an optical spectrum-coded interferometric signal processing technique, the proposed single crystal sapphire optical sensor can measure high temperature up to 1600 oC in the harsh environments with high accuracy, corrosion resistance, and long-term measurement stability. Based on the successfully demonstrated sensor prototype in the laboratory, we are confident of the next research step on sensor optimization and scale-up for full field implementations. The goal for this research has been to bring this temperature sensor to a level where it will become commercially viable for harsh environment applications associated with industries. / Ph. D.