Patent ID: 7718970
Filing Date: 2010-05-18
Classification: G01J,G02B,H01L

Abstract:
1. An infrared detection unit comprising: a base carrying an infrared sensor element; a cap configured to be fitted on said base to surround said infrared sensor element, said cap having top wall with a window; and a semiconductor optical lens configured to be fitted in said window to collect an infrared radiation onto said infrared sensor element; wherein said semiconductor optical lens is formed from a semiconductor substrate to have a convex lens and a flange which surround said convex lens, said flange having a flat face which is held in contact with said top wall of the window at a circumference of said window so as to register said convex lens in said window; and wherein said semiconductor optical lens is formed with an infrared barrier at a portion extending from said flange to a circumference of said convex lens to block the infrared radiation from being directed to said infrared sensor element through the circumference of said window, wherein said semiconductor lens is fabricated through the steps of: preparing said semiconductor substrate having a flat top surface and a flat bottom surface opposed to each other; forming an anode on said bottom surface, placing said semiconductor substrate in an electrolyte solution; flowing a current between said anode and a cathode within said solution to anodize the top surface of said substrate to a varying depth from portions to portions, leaving a porous layer in said top surface; and removing said porous layer from said substrate to leave a convex surface on said top surface, said anode being a metal layer which is deposited on said bottom surface to give a consolidated structure and is configured to give a predetermined distribution of a electric field intensity which varies from portion to portions of said substrate across said top and bottom surfaces of said substrate, thereby providing said porous layer having the varying depth in match with the distribution of said electric field intensity, and said metal layer defining said infrared barrier which reflects the infrared radiation.