Realization of uniform illumination of UV LED circle array

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.