Liquid crystal spatial light modulator : characterization and applications

• Main Author: Kapil Dev.
• Other Authors: Anand Krishna Asundi
• Format: Theses and Dissertations
• Language: English
• Published: 2013
• Subjects: DRNTU::Engineering::Electrical and electronic engineering::Optics, optoelectronics, photonics
• Online Access: http://hdl.handle.net/10356/52951
• Institution: Nanyang Technological University

Liquid crystal spatial light modulator (LCSLM) is an important active and dynamic optical element with a wide range of applications in the fields of optical displays, optical metrology, optical data processing, adaptive optics, bio-imaging etc. Modern LCSLMs have high fill factor, high switching speeds and can provide amplitude and phase modulation of an optical wavefront passing through or reflecting from its active area in real time. An overview of the history of different modern spatial light modulators and their important application as a dynamic optical element in the field of modern display and optical metrology is provided. The amplitude and phase modulation are usually coupled in LCSLMs and a lot of research work is dedicated to characterizing the LCSLM for its optimal use as either an amplitude-mostly modulator or a phase-mostly modulator. The objective of the research work reported in this thesis is to propose a new full-field, dynamic methodology to characterize amplitude, phase and polarization modulation from the transmissive twisted nematic LCSLM and utilize these characteristics for metrology applications. In this thesis, a theoretical model for the twisted nematic liquid crystal spatial light modulator (TN-LCSLM) using both Jones matrix and Mueller matrix calculi is presented. A novel full-field phase modulation characterization method of the TN-LCSLM using digital holography is proposed and demonstrated. Different polarimetric quantities such as diattenuation, retardance and depolarization are determined for the TN-LCSLM using Mueller matrix imaging polarimeter. Important physical parameters of the TN-LCSLM with respect to addressed gray scale value are characterized using digital holographic polariscope. The characteristics of the TN-LCSLM evaluated using different methods reported in this thesis are further used for optical metrology of nanostructure in wire grid polarizer using Mueller matrix scatterometer polarimeter and finite difference time domain (FDTD) simulations.