具非对称非球面镜之指纹辨识器的光学设计(英文)

Optical Design for Fingerprint Identification with Asymmetrical Aspheric Lens

传统的光学式指纹辨识器,为了矫正像差与提升成像品质,会在棱镜的出射面加上一个对称非球面镜(简称传统型) ;本文提出一个新的指纹辨识器结构(简称改良型) ,此结构是在棱镜的光源出射面上,加上一片非对称非球面镜。研究过程中,我们使用点光源近似模型进行设计与模拟,并以数字的方式去呈现改良型的成像品质在各方面均优于传统型的指纹辨识器。在改良型架构下,指纹大小范围在162mm以內,影像对比度皆可达到0.5以上,反观传统型架构,离轴两侧的影像对比度降至0.2以下。

The optical design of optical prism with aspheric lens for fingerprint identification is researched. We propose a new structure for optical prism of fingerprint identification, which has an asymmetrical aspheric lens on the output plane. It is numerically shown under point approximate model that the optical properties of such prism are better than one of optical prism with aspheric lens. When the fingerprint range is 16√2 mm, the results show that the image contrast of our proposed prism is above 0. 5 and the minimum image contrast for optical prism with aspheric lens is only 0. 2.