Micropatterned single lens for wide angle illumination

Abstract

This work presents a simple and effective method for wide angular illumination by using a single lens with micropattern arrays. Unlike a conventional single curvature lens, structured micropattern arrays on a single lens curvature can help light scatter efficiently. Impinged on micropatterens on a curve surface, light undergoes omni-directional diffraction as well as total internal reflection and then eventually increases angular illumination. A hemispherical single lens is microfabricated by a reconfigurable microtemplating and a replica molding methods. The angular illumination of the lens with different pattern sizes under a collimated light source is measured by an optical power meter fixed on polar rotating arm. The illumination angle increases by additional ±35.5 degree, compared to that of the dome lens. The illumination angle and local intensity distribution can be controlled by lens curvature as well as different aspect ratio of micropattern arrays on a lens curvature. Each micropatterned single lens having varied lens curvatures is fabricated by a replica molding technique. Following different lens curvature, the angular illumination of MSL is measured by power meter having a polar rotating arm under LED source. Hemispherical MSL shows ±17.5 degree wider illumination angle than a case of 0.4 curvature. Absolutely, that is ±20 degree wider angular illumination than planar grating having ±9 degree. The two dimensional distribution from concave micropatterned single lens with different lens curvatures under a collimated light source is captured by CCD camera. This 2D distribution shows 3.7 times wider 2D distribution than that of the planar micropattern arrays. And, the angular illumination of the lens is measured under LED source. Hemispherical concave MSL shows ±20 degree wider illumination angle than a case of 0.837 curvature. Absolutely, that is ±40 degree wider angular illumination than planar grating having ±9 degree. ...