像散法於LCD玻璃基板厚度檢測之應用

Application of Astigmatic Method on the Thickness Measurement of LCD Glass Substrate

李宗翰(Zong-han Li)

國立虎尾科技大學/電機資訊學院/光電與材料科技研究所/博士(2006年)

摘要

本文為一種利用像散法量測LCD玻璃基板厚度的方法，利用DVD讀取頭當光源，當光源通過圓柱透鏡後產生像散，最後入射於四象儀感測器(QD)，將待測LCD玻璃基板放入架構中進行量测，由於Snell’s定律，不同的介質有不同折射率，故會產生不同的折射現象，使得光束入射在雷射四象儀原先的聚焦誤差訊號改變，雷射四象儀因此產生電壓變化，利用類比/數位轉換卡(A/D卡)擷取電壓訊號和HP干涉儀所量测的位移量，即可獲得到電壓與位移量的趨勢線，再將待測的LCD玻璃基板放入架構截取電壓值代入趨勢線一階方程式中，轉換成具焦誤差訊號，最後，將聚焦誤差訊號代入本專體所導的幾何光學公式，求得玻璃厚度，再與三次元量床所測得之玻璃厚度互相驗證之，準確度為98%，三倍標準差為2.242μm。

並列摘要

In this study, it is a method of using astigmatism to measure LCD glasses thickness . A DVD Pickup light source passes through astigmatic lens and shoot on the quarter detector than put a LCD glass board in the measurement location.
All of the mediums have different index of reflection , the index will produce different reflection phenomenon , the focus error signal that shoot on the quarter detector will change and therefore the light spot on quarter detector will change , using analog/digital board to get voltage signal and using HP interferometer to measure the stage distance , the relation between distance and voltage will obtain an linear equation . then put a LCD glass board in the measurement location to get numerical voltage and substitute in the linear equation , the experiment result will mutual proof using the geometry-optical equation .

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