Rapid and Accurate Extraction of Optical Parameters for Anisotropic Media by Phase Modulated Ellipsometry
| Autor: | Chuang, Chun-I, 莊俊逸 |
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| Rok vydání: | 2012 |
| Druh dokumentu: | 學位論文 ; thesis |
| Popis: | 101 In this research, we have developed a fast and accurate phase modulated ellipsometry/polarimetry. The optical parameters, the refractive indices and the Euler angles of three principal axes can all be extracted from the intensity waveform within one cycle of modulation (20 μs) through the genetic algorithm. By analyzing the reflected intensity waveforms, we can obtain a set of parametric equations for providing the appropriate boundaries of refractive indices in the numerical procedure. We also found that the two-probe-beam configuration is the optimized configuration for measuring the optical parameters of a uniaxial medium. We suggest 65 and 70° to be the incident angles in ellipsometry, the optimal configuration will be analyzed by the variation of intensity with respect to the optical parameters. For an arbitrarily orientated uniaxial medium, the refractive indices can be accurately obtained with a precision of 10-3 by ellipsometry. For the transparent material with weak anisotropy, one can employ the polarimetry to enhance the resolution of refractive index. By combining the waveform extraction and Fourier transform techniques, the precision of the refractive index of a thick medium (~ 2 mm) has been reached to 10-6. We have applied these techniques for measuring three different photo-refractive materials. Therefore, one can measure the dynamic optical parameters of material under some temporal phasical change. |
| Databáze: | Networked Digital Library of Theses & Dissertations |
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