為發展快速即時之自動對焦技術，提升線上產品檢測的速度，本研究參考像散光學理論，開發一套對焦速度快、精度高之自動對焦模組，並能藉由轉接機構，直接與市面常見的顯微系統相結合。對焦模組利用四象限光二極體偵測像散光斑的形狀變化，建立對焦誤差函數以計算待測物失焦距離。經實驗結果證實，對焦模組已成功應用於PCB 電路板、彩色濾光片、IC晶片等物體，而且失焦範圍在± 200 mm 以內的待測物，僅需花費0.3 秒便能完成對焦動作。

A real-time automatic focus module, integrated with astigmatism algorithm, is introduced in this article. With transition mechanism, engineers can joint the module to existing industrial microscopes to improve product inspection performance. The module is designed with a focus-error function to analyze the defocus distance per the shape variations of laser spot detected by quadrant photodiode. Experiments show that the module has been successfully applied to PCB boards, color filters, and IC chips, etc. and it takes less than 0.3 seconds to focus the objects with ± 200 mm defocus distance.