以臨界角法結合CCD影像擷取技術作表面形貌量測之研究

Three Dimensional Profile Measurement Based on the Critical Angle Method and the Use of a CCD Camera

本論文提出以臨界角強度法結合 CCD 影像擷取技術來量測透明待測物之表面輪廓，此乃由光強度直接轉換成高度之方法，巧妙地做成表面輪廓圖。當一個擴束光經過透明待測物時，由於待測物的表面高度變化，造成穿透光有些微角度偏移，以致於入射至平行四邊形稜鏡時，偏離了原先靠近臨界角的角度，造成靈敏的光強度增減，再以CCD 擷取光強影像。由於待測物的表面高度變化與穿透光經稜鏡之反射率成正比，故可利用反射率變化來描繪待測物的表面形貌與輪廓。本實驗最大優點為不需掃描待測物，即可獲得大範圍的待測物表面形貌。此外，也具有架構簡單、組裝容易、高靈敏度、高解析度等優點。

This paper proposes a new method for the three-dimensional profilemeasurement of a transparent specimen. Based on geometrical optics, thedeviation angle is proportional to the apex angle of a test plate.Measuring the reflectivity of a parallelogram prism used is to detect thedeviation angle when the beam is incident at the critical angle nearby.The reflectivity is inversely proportional to the deviation angle, and it isalso inversely proportional to the apex angle and the surface height. Weused a CCD camera at the image plane to capture the reflectivity profile.Thus, the 3D surface profile is obtained directly.