[OPTICAL REVIEW Vol. 1, No. 1 (1994) 113-117]

Fast and Accurate Phase Retardation Measurement of 0°Twisted Nematic Liquid Crystal Panels Based on the Principle of Homodyne Receiving

Werner KLAUS,1 Nobuyuki HASHIMOTO,2 Kashiko KODATE3 and Takeshi KAMIYA1

1Department of Electronic Engineering, University of Tokyo, 7-3-1, Hongo, Bunkyo-ku, Tokyo, 113 Japan, 2Technical Laboratory, Citizen Watch Co. Ltd., Tokorozawa, Japan, 3Physics Laboratory, Japan Women's University, Tokyo, Japan

(Accepted July 1, 1994)

We describe herein a method to measure quickly (in less than 2 min) and accurately the phase retardation between the extraordinary and ordinary axis of homogeneous or 0° twisted nematic liquid crystal panels. Owing to the homodyne detection scheme, the setup allows us to probe liquid crystal (LC) panels with an optical power down to a fraction of 1 nW and, hence makes it possible to focus the light beam to a spot of only a few wavelengths in diameter without heating or inducing observable variations in the liquid crystal. The dependence of the phase retardation on the LC driver frequency and the temperature are presented and compared with the theoretical prediction.

Key words : homogeneous nematic liquid crystal, phase retardation, birefringence, homodyne interferometry