Study on the optical path and index of refraction measurement method of the liquid crystal cells with Zeeman dual-frequency laser

• Main Authors: Guei-Fan Lin, 林桂帆
• Other Authors: Tien-Jung Chen
• Format: Others
• Online Access: http://ndltd.ncl.edu.tw/handle/5vk58z

碩士 === 國立臺北科技大學 === 光電工程系研究所 === 103 === Zeeman dual-frequency laser is a common-path heterodyne interferometer. It has many advantages, such as real-time measurement, hardly affected by the environment and vibration. The light source we utilized Zeeman laser which beat frequency is up to 2.7MHz and it provides the higher stability during the measurement. In addition, the optical structure of this experiment is much easier than the experiments which use other measurement system. In this paper, we used the Zeeman laser to measure the optical path, birefringence, index of refraction. We used plane-parallel aligned cell. First, we discussed on the properties of Zeeman laser, For example: beat frequency, the effect on the beat frequency of the alignment. Second, we measured the nematic LC(NLC), E7, optical path after applying voltage. From the experimental result, we obtained the birefringence of E7. For the blue phase liquid crystal(BPLC), we used the oblique incidence method to measure the phase-voltage relationship of blue phase liquid crystal. We obtained the induced birefringence δn is independent of the oblique incidence angles and the δn is proportional to E2. The results match the Kerr effect formula. Finally, we rotated the LC cell and applied voltage to measure the birefringence of E7, ne, no.