色彩光柵的設計、製作與量測

Abstract

光柵和濾光片都是光學上常用的分光元件，但在利用濾光片時，普遍存在效率不佳的缺點，此一效率不佳的問題使得整個機構需要更強的光源才能達到足夠的光強度。本論文為設計一色彩光柵提供給投影電視使用，設計光柵改善上述使用濾光片的缺點。過去所用多為標量繞射理論，在光柵週期和光波長十分接近時，此理論已無法精確的分析預測繞射效率，故改以嚴格耦合波理論為基礎，建構光柵模擬程式。利用此一程式模擬出適合的光柵參數與環境參數，製作上由於設計的光柵線寬相當細小，所以利用電子束微影的製作技術去製作光柵。最後，我們對量測的繞射效率和原先設計之間差異逕行討論，並檢討誤差的原因。

Both the gratings and filters are commonly used for separating light in the optics, but the efficiency of filters for separating light is generally not good. So the system with the filter needs more power of light in order to have enough light intensity. In this thesis we designed a color-grating, instead of the filter, to separate light. With the color-grating we can increase the efficiency to 80%. Since the line-width of the grating is same order of magnitude as the wavelength of light, instead of the simple scale diffraction theory, we have to use the rigorous coupled-wave theory (RCWT) for calculation of the grating efficiency. So an optimization program by the RCWT is made for determining the structure parameters of gratings and environment parameters, such as line-width, the depth, incident angle …etc. The line-width of our gratings is so small that we made them with E-beam lithography techniques. Finally, I would discuss and analyze the difference between the measurements and the calculations.