本論文提出一套新的自動準直儀技術-「疊紋式自動準直儀系統」，其是將疊紋理論加入傳統自準儀系統中，分析待測平面偏轉時產生的疊紋相位偏移來判斷其偏轉角度的變化，研究方法如下:將光柵置於透鏡焦平面上，光柵影像穿過透鏡後由待測平面反射，再次經透鏡聚焦成像於影像偵測器上；疊紋現象為兩組或兩組以上光柵相疊所形成具另一低頻的週期性條紋，在此系統中的第一道光柵為偵測器所量測到的光柵影像，第二道光柵則為電腦中已儲存的數位光柵影像，當第一道光柵影像隨著待測平面偏轉而偏移，疊紋條紋隨之偏移，利用亞條紋演算法來分析疊紋條紋的偏移量我們可求出待測平面的偏轉角度。
在本次實驗中，系統的量測靈敏度可藉由調整光柵間距及透鏡焦距來改變，當所使用的透鏡焦距為300 mm時，光柵間距100 m下的系統靈敏度為10.48，量測解析度為0.034 arc-sec，將光柵換為間距200 m，系統靈敏度為5.24，量測解析度可達0.024 arc-sec。

A novel autocollimator using the formation of moiré image is proposed. By analyzing the deviation of the phase of the moiré fringe, we can calculate the angular deflection of the sample flat. In the system configuration, the grating is located on the focus plane of the lens. The image of the grating propagates through the lens and be reflected by the flat mirror. The reflected back image enters in the lens again and forms image on the screen of the image detector.
The moiré fringe is obtained from the superposition of the two images of gratings. In the experiment, the first grating image is received by the detector, and the second grating image is the digital image saved in the computer. When the sample flat is be deflected, the image of grating will have displacement, we can get the angular deflection of the sample by using sub-fringe method to analyze the displacement of the moiré fringe.
In this experiment, the measurement sensitivity of the system can be controlled by adjusting the grating pitch and the focus length of the lens. According to the experiment result, the measurement sensitivity is 10.48, and the accuracy is 0.034 arc-sec by using 300 mm lens and 100 m grating. With the 200 m grating, the measurement sensitivity is 5.24, and the accuracy can achieve 0.024 arc-sec.

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