中文摘要：

现有的虹膜识别仪通常要求人眼在较小的范围内成像,许多被测试者由于需要反复调整位置才能满足虹膜图像的采集要求而感到心烦,如果能够给出人眼的拍摄范围,将方便用户的使用。研究并建立在人眼偏离镜头聚焦位置的情况下,所拍摄虹膜图像清晰程度与人眼到镜头之间拍摄距离的对应关系,选择并通过实验评价了用于表述图像清晰程度与拍摄距离对应关系的四种评价函数的性能。实验结果表明：当人眼在90～150mm内移动时,所拍摄的虹膜图像清晰程度先逐步增大,到达峰值后,再逐步减小;当人眼与摄像机之间的最大可拍摄范围为106～132 mm时,就可以获得清晰程度满足识别系统性能要求的图像,得到比较稳定的识别效果。

英文摘要：

The existing iris reader usually requires human eye imaging in smaller depth of filed,many users become upset because of adjusting position repeatedly when acquisition the iris images.If the shooting range can be gave,it will be convenient for the use of users.Under the condition of the human eye deviating the focus of the camera,this paper studied and established the corresponding relationship between the iris image clarity and the shooting distance between the eye and lens,and evaluated by experiments the performance of four evaluation functions being used to describe the corresponding relationship between the image clarity and the eye shooting distance.Experimental results show that when the human eyes move in 90~150 mm range,the iris image clarity firstly increases to maximum gradually,then reduces gradually;when the maximal shooting range between human eyes and camera is 106~132 mm,the acquired iris image clarity will be enough for the performance of the iris recognition system,thus,the steady recognition effect can also be obtained.