次微米的雷射位移感測器之研究

Abstract

本論文的研究目的在於根據三角測量法原理去設計一個20 kHz高速掃瞄且解析度達到次微米級的雷射位移感測器，描繪出一維的物體表面形貌，以運用在工業的產品缺陷檢測上。由探究雷射三角測量法的原理與架構來提高解析度；分析成像透鏡產生的光學像差並使用光圈加以修正；從雷射光特性得知，藉由擴束鏡和聚焦透鏡來獲得較小的檢測光點以提昇精確度。搭配輸出模態佳、功率可調的倍頻綠光固態雷射以及雜訊低、靈敏度高的影像感測器組成雷射位移量測系統， 對於量測多晶矽的表面位移量，提出最佳化的質心演算法以達到次微米級解析度和高速量測目的。

The purpose in this study is to design a laser triangulation displacement sensor with high speed about 20 kHz and resolution up to sub-micron class, which can be applied to inspection in the industry by describing one dimension profile. We study principle of triangulation to improve the resolution and correct the optical aberration with aperture. To use beam expander and focus lens with analysis of laser feature gets smaller spot diameter which raises precision. Diode pumping solid state laser has fine output mode and power modulation and image sensor possesses the characteristic of low noise and high sensitivity. Integrate them into displacement measurement system. For poly-silicon surface displacement, we propose optimization centroid algorithm to achieve sub-micron resolution and fast sampling speed with the measurement system.