Research On Phase Detection Of Liquid Crystal Grating

As a kind of widely used special functional material, liquid crystal has the features of flowing power and viscidity like liquid, and the anisotropy like crystal. In the features of liquid crystal, voltage-dependent birefringence effect of liquid crystal is a very important feature. Fast development of the liquid crystal optical devices make miniature, inexpensive adaptive optics and space optical communication systems become possible. Such accurate quantification of the incident wavefront phase modulation capability is the key to realize the above-mentioned applications, which is limited to the measurement method, the incident wavefront phase modulation capability is difficult to accurately measured and calibrated.The technology of phase detection of Liquid Crystal Grating is a difficult research in current domestic and overseas. The existing method has the bad anti-vibration ability of phase detection for Liquid Crystal Grating, detection is not strong commonality and phase recovery algorithm is complex, a new method for measuring Liquid Crystal Grating has been proposed in this dissertation. As the Liquid Crystal Grating is not easy to obtain, the experiment selects the shear plate as a optical detection device in order to verify the effectiveness of the method.The orthogonal phase shifting conjugated technology for testing the phase modulation of Liquid Crystal Grating has been proposed. The basic theory and key technology was explored in this dissertation. And the main research work focuses on the following aspects:1. For the Liquid Crystal Grating, when incident beam is polarized light, orthogonal phase shifting method has been researched in the dissertation. There is only a short part of non-coaxial optical path based on such measurement, the rest are coaxial system completely. The detection system anti-vibration capability has been improved in this system structure of the common optical path;2. The diffraction-type liquid crystal device modulation phase detection was deeply studied. Based on the Jones matrix, the phase of Liquid Crystal Grating was calculated. The adopted principles includes the phase shifting interferometry combining with phase conjugation technology. The incident beam was orthogonally polarized into phase reference arm and signal arm as polarized light in common optical path, the phase modulation of Liquid Crystal Grating was detected. The above method has great difference with ordinary Liquid Crystal Grating phase detection of the non-common optical path measuring modulation and complex phase recovery algorithm;3. Constructing the common modulation phase detection system of the Liquid Crystal Grating and evaluating the overall performance of the method was the key in this dissertation. Proving the effectiveness of the method mentioned,the wavefront phase distribution of the shear plate was measured. The phase detection in the strong diffractive liquid optical devices can be realized in the conjugate optical system.