計算機光學於虹膜取像之研究

Abstract

計算機成像光學又稱數位光學，結合了傳統光學取像系統與影像還原技術。為滿足許多成像系 統所需要的特殊功能，如擴展景深、超淺景深以獲取三維資訊、頻譜影像及高成像品質要求， 整合介面的光學取像與後段結合影像處理已成為光學產業的趨勢及下一波的明星技術。目前虹 膜辨識系統受限於較淺的景深，而景深不足將導致影像擷取系統不容易擷取到使用者清晰的影 像，亦即當使用者在行動的過程，會因為些許的失焦而造成影像無法辦認。本計畫預計建置一 組望遠取像系統，在非同調光學系統孔徑位置，設計自由型相位波前編碼與數位濾波信號處理 技術，可在長焦距遠心系統中達到全幅對焦的表現，此項技術突破目前一般虹膜識別的限制， 實作出遠距離、高精確度的虹膜取像系統 (達三米以上)，可廣泛應用於快速通關或是流動率極 高之機場或是學校出入口。

Computational imaging systems are novel scheme composed of generalized imaging optics and post signal processing capability. The unique characteristics of computational imaging technology are useful to advantage in iris recognition applications. A major difficulty in current iris capturing system is a very shallow depth-of-field that limits system usability. Such constraint often results in the blur of the captured iris images, which in turn, results in the degradation of iris recognition accuracy. In this study, we propose a novel telescopic layout jointed with free-form phase wavefront encoding to offer a significant stand-off iris image acquisition distance (over 3m). The new approach can greatly increase the depth-of-field over that possible with traditional optics, while keeping sufficient recognition accuracy. In proposed implementation the combination of optics, detectors, and image processing all contribute to the iris recognition accuracy and efficiency, which is suitable for deployment at airports or school access in dynamic environment.