干涉相位量測術及其應用 於光學參數之測量

Abstract

利用移相干涉術與外差干涉術等的精密干涉量測技術測量各種系統中所引入的偏光相位變化或偏光間的相位差；將所得之數據代入Fresnel方程式或雙波長干涉術中相位變化與波長變化的式子中，即可測得如折射率與厚度等之光學常數。首先以移相干涉術在改良型的Twyman-Green干涉儀中，測量全反射時p-偏光的相位變化，可得待測物的二維折射率分佈；接著與顯微鏡相結合，測量細胞緊貼於稜鏡斜邊時，由於全反射所引起s-與p-偏光間的相位差，可得透明的細胞的灰階相位成像圖；其次設計出一組光學裝置，結合外差干涉術與雙波長干涉術，可在該裝置中測得厚度遠大於波長透明板厚度及其折射率。最後，為了將常用於單點量測的外差干涉術擴充至具有實用性的二維量測；經由各種模擬計算，導出可得最小誤差的最佳測量條件。另外這些干涉相位量測技術均具有光學結構簡單、操作容易、穩定度高及快速測量等優點。

High accuracy interferometric measurement techniques such as the phase shifting interferometry and the heterodyne interferometry can be applied to measure the phase shift of a polarized light beam or the phase difference between two orthogonal light beams in several interferometers. Substitute these data into the special equation derived from Fresnel equations or the equation used in the two-wavelength interferometry, the optical constants including the thickness and the refractive index of a material can be obtained. Firstly, the phase-shifting interferometry is applied to a modified Twyman-Green interferometer to measure the phase shifts of a polarized light beam due to the total internal reflection, and the two-dimensional refractive index distribution of the tested material can be obtained. Next, the optical configuration is improved and a microscopic objective is added, a cell contacted at the hypotenuse of a prism. The phase difference distribution between the s- and the p- polarized light due to the total internal reflection is measured similarly, and the transparent cell can be phase-imaged and displayed in grey-level. Then, a novel optical configuration combined the heterodyne interferometry and two-wavelength interferometry is designed to measure the thickness and the refractive index of a thick transparent plate. Finally, the heterodyne interferometry which is often suitable for one-point measurement is extended for two-dimensional measurement. Some simulations of different conditions are calculated iteratively, and an optimal condition is derived. Besides, they have several merits such as simple optical setup, easy operation, and rapid measurement.