使用波前感測方法之測距技術

Abstract

近年來，由於雷射與電子電路技術的進步，三維影像技術正快速的發展，相關的產品也已經商業化並應用在民生與工業領域中。不同於以往影像感測器的平面影像，三維影像包含了被攝物的深度資訊，因此常被用在機器人視覺、汽車安全、雷射追蹤、逆向工程與體感電子遊戲。一般而言，在及時三維影像偵測器中，平面影像可藉由CCD與CMOS影像感測器來取得。深度則可由常見的測距方法來測得，像是飛時測距、三角測距與超音波測距。然而超音波測距與光學測距方法相比資料擷取速度較慢且空間解析度較低、飛時測距需要複雜的電路、三角測距需要精密的光路設計，因而大大增加了系統成本與整合深度與平面量測的困難度。 因此，為了降低整合深度與平面量測的困難度，本論文提出一種利用波前感測方法的測距技術，其藉由一個由微透鏡陣列與CCD影像感測器所組成的波前感測器來量測從光點所發出的球形波前來進行距離量測，所以不需要複雜的電路與光路設計。目前的研究成果有：一、理論分析與模擬，模擬的結果顯示在量測範圍0.5~5公尺之間的測距誤差皆小於1 mm；二、測距器的建置，實驗的結果顯示在量測範圍0.5~3公尺之間的相對誤差大約為8％ ，3~5公尺的相對誤差則在10％以上。在測距精確度上，未來仍有改善空間。

In recent years, range imaging technology has been highly developed because of the progress of laser and electric technology. Unlike traditional CCD and CMOS cameras, the depth camera captures 3D images which contain the depth data of the target so that is often used in robot vision, vehicle safety, laser tracking, reverse engineering and electronic games. Generally in a depth camera, the two-dimensional measurement can be accomplished by using CCD and CMOS image sensor arrays and the depth of targets can be measured by various range finding techniques such as time of flight method, triangulation method, and ultrasonic method. Nevertheless these range finding methods often need complex circuit and optical system that increase the difficulty to integrate the two-dimensional image sensor with the range finder. This thesis presents a range finding method which use a wavefront sensor to sense the spherical wavefront of a point light source for calculating the source’s position. This method does not need complex circuit and the wavefront sensor is easily fabricated. The analysis and simulation show that the range error is smaller than 1 mm in the measurement range from 0.5 m to 5 m. A range finder was accomplished and the experiment using LED showed that the relative range error was about 8％ in measurement range from 0.5 m ~3 m and the relative range error was larger than 10％ in 3 m. Problems encountered during the study, such as the range accuracy, are discussed for future work.