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Optics and Lasers in Engineering, Volume 51, Issue 7, July 2013, Pages 861-866.
Chun-I Chuang, Shiuan-Huei Lin, Yu-Faye Chao.
Department of Photonics and Institute of Electro-Optical Engineering, National Chiao Tung University, 1001 University Rd., Hsinchu 30010, Taiwan, ROC and
Department of Electrophysics, National Chiao Tung University, 1001 University Rd., Hsinchu 30010, Taiwan, ROC.
Abstract
An improved phase modulated technique has been implemented to increase the speed and accuracy of optical parameters extraction for a uniaxial bulk media. In combination of the genetic algorithm, we show that not only the complex refractive indices, the inclination and azimuth angles of optical axis can also be extracted. Furthermore, by using a two-probe-beam configuration, the speed of convergence can be improved by 5-times. Such a high speed and accurate method can be applied for the in-situ measurement of dynamic materials.
Additional information
An improved phase modulated technique has been implemented to increase the speed and accuracy of optical parameters (Ops) extraction for a uniaxial bulk media. In combination of the genetic algorithm, we show that not only the complex refractive indices, the inclination and azimuth angles (OA) of optical axis can also be extracted. In this research, we have established a rapid method to measure the Ops of uniaxial crystals by using two probe beams, simultaneously. Through the numerical analysis, we not only suggest the appropriate incident angle pair to measure the complex refractive indices and OA directions, we also provide the initial boundaries for reducing the computation time in GA. The analysis indicates that this two angle of incidence photo modulated ellipsometry can measure the complex refractive indices of a uniaxial crystal when its OA is oriented in any direction, but can determine its direction only when the OA is orientated more than 5o off normal.
