外差式相位偵測技術於平板玻璃之光熱係數的量測

Heterodyne Interferometric Measurement of the Thermo-Optic Coefficient of Glassplate

張春田(Springfield Chang) ； 林文濱(W. B Lin) ； 陳聖鐘(S. C. Chen) ； 李振銘(C. M. Lee) ； 黃俊憲(C. S. Huang)

《智慧型系統工程應用研討會》 第4屆 (2010/05) Pp. 214-217

https://doi.org/10.30176/ISC.201005.0214

摘要

外差式相位偵測技術於平板玻璃之光熱係數量測，其拍差信號相關於調制之載波及上下旁波帶在共振腔內行走之光程差，從溫度之相關性，可求出玻璃平板之光熱係數。
將半導體雷射調制－射頻(R.F.)訊號，形成上下旁波帶及載波，三個頻率之雷射光，入射於8mm厚度，BK7玻璃光學平板，其多重反射光入射於光檢測器，光學平板形成法德培羅(Fabry-Perot)之共振腔(resonator)，光學平板調制雷射光之射頻訊號，經光檢測器取得電訊號，此訊號與調制半導體雷射之射頻(R.F.)訊號經由混波，此混波器，具有相位比較器之功能，並取得兩訊號之相位差，及轉換爲電壓訊號，形成外差式干涉儀之訊號。光學平板置於電子致冷器(T.E, Cooler)，並連續加温，外差式干涉儀將輸出連續，且具有週期性正負電壓，並得知雷射光在光學平板內光程變化一個波長，所須温度週期，將温度週期代入公式，求得光熱係數(dn/dT)=1.7×10^(-6)(上標 °)C^(-1)。

關鍵字

外差式干涉 ； 法德培羅之干涉儀FFPI ； 光熱係數 ； 拍差信號 ； 光纖耦合器

並列摘要

The heterodyne interferometric measurement, resulting from the beating of the carrier and two side-band frequencies, is related to the phase shift difference between the carrier and the side-bands. This phase shift difference is determined with a phase sensitive detection technique and is found to be temperature dependent. From the temperature dependence, the thermo-optic coefficients of the plate glass are determined.
We used radio frequency signal to modulate laser diode and got the side band and carrier laser beam. The laser beam had three frequency and projected optical plate. The refracted laser beam from optical plate projected a optical detecter and created R.F. signal. The R.F. signal compared a radio frequency signal modulated laser diode and got phase difference signal and formed heterodyne interferometer.
The optical plate on T.E. cooler continuously changed temperature and got a period signal. We know the temperature period when optical plate changed a optical wavelength path. We got thermal-optic coefficients (dn/dT)=1.7×10^(-6)(superscript °)C^(-1).

並列關鍵字

heterodyne interferometry ； FFPI ； thermo-optic coefficients ； beating signal ； fiber coupler