Image pickup apparatus

Abstract

An image pickup apparatus includes an image pickup optical system and an image pickup unit configured to receive an image formed by the image pickup optical system. The image pickup optical system includes an optical element having optical incident and optical emergent surfaces disposed between an aperture stop and an object and a fine textured structure having a mean pitch shorter than a wavelength of visible light and formed on at least one of the optical incident and optical emergent surfaces. The conditions 3.5<RA/R 0 and 60° <2ω are satisfied, where RA is an effective diameter of the optical surface having the fine textured structure, R 0 is a diameter determined by a height when light rays forming an image on an optical axis pass through the optical surface having the fine textured structure, and 2ω is an angle of view in image taking limited by a size of the image pickup unit.

1 . An image pickup apparatus comprising:
 an image pickup optical system including an optical element having optical incident and optical emergent surfaces and a fine textured structure having a mean pitch shorter than a wavelength of visible light, the fine textured structure being formed on at least one of the optical incident and optical emergent surfaces, the optical element being disposed between an aperture stop and an object;   an image pickup unit configured to receive an image formed by the image pickup optical system; and   a flare-cut stop disposed between the aperture stop and the object, the flare-cut stop being provided with a non-circular opening,   wherein the optical surface on which the fine textured structure is formed is disposed between the flare-cut stop and the object.   
     
     
         2 . The image pickup apparatus according to  claim 1 , wherein the following condition is satisfied:
   60°<2ω
   
       where 2ω is an angle (degrees) of view in image taking limited by a size of the image pickup unit. 
     
     
         3 . The image pickup apparatus according to  claim 1 ,
 wherein the opening of the flare-cut stop is rectangular,   wherein the image pickup unit is rectangular, and   wherein long sides of the opening of the flare-cut stop and long sides of the image pickup unit are arranged in a same direction, and short side of the opening of the flare-cut stop and short sides of the image pickup unit are arranged in a same direction.