From old times human wanted to watch lifelike moving images and this desire gave rise to various optical implements in the 19th century. One of these is the motion picture. The projection technology based on the film made man's dream at least come true but he also wanted to watch what was happening in the other side of the world. So, human invented the electronic projection display like CRT. With the help of this technology, man simultaneously watched the things of the other side of the world. After that, people used the electronic projection display technology as a part of the efforts to bring live television programs to the theater through a big screen. However the big screen was not satisfactorily bright. To solve this problem the LCD(liquid crystal display) technology was devised, but it had faults such as low optical efficiency, low brightness, and even heat generation. However, with the rapid development of MEMS(micro-electro-mechanical system), reflection-type light valves which would be able to replace the previous light valves have been invented. DMD(digital micromirror device) which was already developed by Texas Instruments and TMA(thin-film micromirror array) which are now being developed by Daewoo Electronics Co. are the representative examples and these light valves consist of an array of micromirrors.
As we see in the term "reflection-type", they reflect the light from a light source to screen. Comparing to other projectors using the transmission-type light valve or LCD, they are excellent in brightness, resolution and pixelation. Especially, the display that uses DMD or TMA has higher optical efficiency than others and it will contribute to the development of display industry.
We calculate the total optical efficiency of the TMA projector by each optical efficiency categorized by lamp coupling, optical transition and TMA pixel, and the TMA pixel efficiency constitutes fill factor, reflectance and mirror flatness. And due to the limitations of the manufacturing processes of micromirrors, the surfaces of micromirrors are distorted to some extent. If so, it influences on the light modulation for grayscale as well as its optical efficiency. As a result of that, the TMA projector does not get to perform well.
Thus, in this research, as a part of the efforts to enhance the performance of the TMA projector I will examine DMD and TMA that are a new pattern of spatial light modulator and then analyze how and how much the form errors of the surface of a micromirror influence on the optical performance. Saying more specific terms, I will do modeling based on the theory of wave optics and quantitatively calculate the optical efficiency and the grayscale line through simulation and then compare the analytical value with experimental value. In addition, I will investigate into the change of the optical efficiency and the grayscale line as the form errors of the surface of a micromirror increase. And lastly, since the contrast ratio of image decreases as the result of the change and it has negative influence on image quality, I simply considered and analyzed an alternative to improve it.
