Measurement of two-dimensional refractive index distribution using high sensitivity total-internal-reflection phase-shifting interferometry

• Main Authors: Chen, Yu-Yun, 陳昱澐
• Other Authors: 林俊佑
• Format: Others
• Language: zh-TW
• Published: 2018
• Online Access: http://ndltd.ncl.edu.tw/handle/5s443a

碩士 === 國立彰化師範大學 === 機電工程學系 === 106 === In this thesis, a high-sensitivity total-internal-reflection (TIR) phase-shifting interferometry is proposed for measuring the two-dimensional (2D) refractive index distribution of a material. A linearly-polarized expanding beam after traveling through a Soleil-Babinet compensator and a spatial filter enters into a high-sensitivity TIR apparatus. The TIR apparatus consists of a phase shifter (formed by combining a half-wave plate and a quarter-wave plate that display specific optic-axis azimuths), an isosceles right-angle prism whose base is directly contacted with a tested material, and an analyzer. The interference signal of the TIR beam output from the apparatus is captured by a CCD camera. Based on the four-step phase-shifting method by modulating the Soleil-Babinet compensator, the 2D phase difference used to determine the refractive index distribution of the material is obtained. Since the 2D phase difference displayed by therefractive indexof the material is linked to the azimuth angle of the quarter-wave plate axis and analyzer transmission axis, the high sensitivity measurement are achievable by adjusting the transmission axis. The experiment demonstrated that the sensitivity and the resolution of 8.96×103 /RIU and 4.46×10-6 RIU can be achieved. In addition to high, tunable sensitivity and excellent resolution, the designedmethod also offers the merit of high stability due to its common-path configuration.