Design of High Optical Throughput Projection Optics and Analyses of Image Quality

• Main Authors: Chong-Min Chang, 張宗閔
• Other Authors: Han-Ping D. Shieh
• Format: Others
• Language: en_US
• Published: 2001
• Online Access: http://ndltd.ncl.edu.tw/handle/58755906942518271066

博士 === 國立交通大學 === 光電工程所 === 89 === Abstract The demand for the display systems with high information content is immediate in the information-booming era. Such displays shall exhibit the features of high resolution, large screen, and high image quality to fully convey the information into the human visual system. A promising display technology that has recently boomed is the projection display, which fuses the miniature light valves and the innovative projection optics to produce the images. The projection displays capable of displaying large, bright, seamless and vivid color images are expected for various applications, including high-definite televisions, conference presentation, workstation monitors, and digital electronic cinema. Establishment of the simulation models and optimization techniques for projection display applications are the first objective devoted in this thesis. The influences of individual optical components, light sources, and their combination upon the image quality were investigated to assist the development of optimal optical systems. Furthermore, a complete method was proposed for dealing with light propagation in optically anisotropic media. Generalized formulas were derived to determine the multiple reflection and refraction at an interface between arbitrary-oriented biaxial media. This simulation scheme is applicable for the analysis of birefringence films and optical devices incorporating polarization effects. The projection optical system is the heart of a projection display, which strongly impacts upon the system performance. The second objective of this research is to explore the optical systems with high optical throughput. The liquid crystal displays (LCDs) utilizes only one polarization for light modulation, leading to >50% light loss. To increase the light utilization, a novel polarized illumination system was proposed for LCD projectors. This optical system employs the unique off-axial design to convert random polarized light into linearly polarized light. Through this polarization conversion scheme, the optimized system can be nearly double the light throughput. Simultaneously, the optical system converts a circular-shaped beam into a rectangular one, and provides a uniform irradiant distribution on the light valve. The miniature light valves fabricated by the micro-electro-mechanical-systems (MEMS) technology are immerging for projection applications because of their inherent natures of high aperture ratio and fast switching speed. A novel optical system for the projection displays with the digital micromirror devices (DMDs) was presented to enhance light efficiency and image contrast. A high-efficiency rod integrator was adopted in the illumination optics to perform the shape conversion, yielding a uniform rectangular-shaped illumination beam on the DMD surface. In addition, a unique light separator was proposed in the imaging optics to adequately separate the incident and reflected beams. Because the light paths overlapping are eliminated, this optical system results in both high brightness and high contrast.