新型外差式干涉儀與相位計之研究

Abstract

微小量測及光學面之表面粗糙度量測的新型外差式干涉儀與相位計。此外 差式干涉儀的差頻由電光移頻調制器產生而來 ，其頻率範圍從幾百Hz到 幾十kHz 均可，因此在不降測量的解析之下，便可很容易地製造出用於相 位計的電子信號處理系統。不但可以做即時的量測且光學架構簡單、成本 低廉。另外本文提出藉由電壓控制振盪器(VCO) 做成的新型相位計，有著 很好的解析度。其方法是先將經由zero-crossing 電路的測試信號與心參 考信號，取出兩信號的時間差並轉換成電壓值，再由VCO 將此電壓值轉換 成相對的振盪頻率，最後由VCO 的特性曲線，便可得到兩信號的相位差值 。我們由實驗的結果可以看出，此相位計的解析度可達0.005 度 上。 A new type of heterodyne intereferometermall displacement and optical surface roughness,of phase meter are presented. In this type of heterodyne interferometer, the difference frequency between two interfering beams is generated by an electro-optic modulator, and can be en at the range from several hundred Hz to several 10kHz. Consequently, a general and inexpendsive electrical signal processing circuit can be used for the phase meter without sing the measuring resolution. It can be easily operated in real-time and its optical structure is sample and compact. In addition, a new type of phase meter using a voltage controlled oscillator (VCO) is fabricated for better resolution. The time difference between the zero-crossing points of the test signal and the reference signal is converted into a voltage level. Then this voltage level is sent to a VCO and a oscillationsignal with a corresponding frequency is obtained. According to the characteristics of the VCO, the phase difference between e two signals can be calculated. And it has a resolution better than 0.005 degree.