以外差干涉術測量葡萄糖溶液之圓偏極折射率及濃度

Abstract

光學活性是某些介質的一種特性，這種特性可應用在許多領域，如葡萄糖溶液濃度的量測及分子結構的探討等方面。在本研究中，首先推導光在光學活性物質界面處的反射及穿透時的物理特性；其次由所推導而得的結果並配合旋光外差干涉技術，提出一種可同時測量葡萄糖溶液的濃度及圓偏極折射率的方法。在本研究中，我們以一線性偏振光通過電光晶體與四分之一波片產生一個具有頻差的旋光外差光源，由所測得的干涉信號相位差來求得葡萄糖溶液之圓偏極折射率及其濃度。此法的架構簡單，所需的光學元件少，且為共光程的結構，有高的穩定度及測量解析度。

Optical activity is a special characteristic of some media, and it can be applied to many fields, such as the measurement of the concentration of a glucose solution and the investigation of the molecular structure etc. Firstly, the physical characteristics of the reflection and transmission at the surface of an optical activity medium are derived. Based on the derived results and the circularly polarized heterodyne interferometry , a method that can measure the concentration of a glucose solution and circularly polarized indices at the same time is presented. In this method, a linearly polarized laser source with an electro-optic modulator and a quarter-wave plate is used as a circularly heterodyne light source. The circularly indices and the concentration of a glucose solution can be estimated by substituting phase differences of the interference signals into the above derived results. It has some merits, such as a simple optical setup, high stability and resolution.