Optical filter, method of manufacturing optical filter, optical system, and imaging apparatus

Abstract

An imaging apparatus comprises an optical system including a plurality of optical elements having finite refractive power and an electronic imaging device disposed at an image side of the optical system. At least one of the plurality of optical elements is made of resin, and an infrared-cut coating is applied to at least one face of the optical element that is made of resin.

1 - 34 . (canceled) 
   
   
       35 . An optical filter comprising:
 a substrate that absorbs infrared light;   an infrared-cut layer, formed on one surface of the substrate, that reflects infrared light; and   an antireflection layer formed on the other surface of the substrate,   wherein the infrared-cut layer and the antireflection layer are formed of multilayer structures in which a plurality of thin-film layers having different refractive indexes are laminated.   
   
   
       36 . An optical filter according to  claim 35 , wherein the substrate is made of resin. 
   
   
       37 . An optical filter according to  claim 35 , wherein the thickness of the antireflection layer and the thickness of the infrared-cut layer satisfy the following condition:
   0.05≦(layer thickness AR)/(layer thickness IR)≦1  (11)   where, layer thickness AR is the thickness of the antireflection layer, and layer thickness IR is the thickness of the infrared-cut layer.   
   
   
       38 . An optical filter according to  claim 35 , wherein the number of the layers in the antireflection layer and the number of the layers in the infrared-cut layer satisfy the following condition:
   1<(number of layers IR)/(number of layers AR)≦5  (12)   where number of layers IR is the number of the layers in the infrared-cut layer, and number of layers AR is the number of the layers in the antireflection layer.   
   
   
       39 . An optical filter according to  claim 38 , wherein the number of the layers in the antireflection layer and the number of the layers in the infrared-cut layer further satisfy the following condition:
   1<(number of layers IR)/(number of layers AR)≦2.5  (13)   where number of layers IR is the number of the layers in the infrared-cut layer, and number of layers AR is the number of the layers in the antireflection layer.   
   
   
       40 . An optical filter according to  claim 35 , wherein the transmittance for light in a wavelength range from 750 nm to 850 nm is approximately 10% or less compared to the average transmittance in a wavelength range from 500 nm to 550 nm. 
   
   
       41 . An imaging apparatus comprising:
 an optical system including an optical element having a finite refractive power;   an optical filter according to  claim 35 ; and   an electronic imaging device, disposed at an image side of the optical system, which light transmitted through the optical filter enters.   
   
   
       42 - 50 . (canceled)