为构造指纹荧光检测中所需的均匀照明紫外光源, 选择紫外LED阵列照明。采用光电探测器检测单颗LED的辐射角分布, 拟合单个LED角分布函数; 用8颗LED均匀置于半径为10 mm的圆环上, 在圆环上方5 mm处的中心轴上放置一个LED; 在给定的观察屏上照度不均匀误差下, 根据斯派罗法则, 确定观测屏与圆环阵列之间的距离, 从而实现LED圆环阵列的照度分布均匀化。也可以给定观测屏到圆环的距离, 确定轴上LED放置点到圆环的距离。实验结果表明, 观测屏到圆环距离为11.0 cm时, 在半径为10.0 mm的圆域内, 照度不均匀相对误差小于1.27%。

Ultraviolet (UV) LED array illumination was chosen for constructing uniform illumination ultraviolet light source required in the fingerprint fluorescence detection. The angular distribution of single LED radiation was tested by using photoelectric detector, and the angular distribution function of single LED was fitted. Eight LEDs were placed on the circle with radius of 10 mm evenly, and a LED was placed in the center shaft 5 mm above the circle. For a given observation screen under the uneven illumination error, according to the laws of the Spyro, the distance between the viewer and the circle array was determined and then the uniform illuminance distribution of LED circle array was realized. when the distance from observation screen to circle was given, the distance between the LED placed point on axis of the circle to the circle could be determined too. Experimental results show that the distance from the observation screen to the circle is 11.0 cm, the relative error of uneven illumination is less than 1.27% within a circle with radius of 10.0 mm.