Diffractive optical element and method for manufacturing same

Abstract

An element includes a first resin layer and a second resin layer disposed between a first glass lens substrate and a second glass lens substrate, a boundary surface between the first resin layer and the second resin layer having a diffraction grating shape including a plurality of inclined surfaces and wall surfaces. The second resin layer is composed of a fluororesin in which fine metal oxide particles are dispersed. Since a refractive index distribution easily occurs in this material during curing by application of ultraviolet light, by applying ultraviolet light substantially perpendicular to the inclined surfaces of the diffraction grating shape, a refractive index distribution is formed in the thickness direction perpendicularly to the inclined surfaces.

What is claimed is: 
     
         1 . A method for manufacturing an apparatus including a glass lens substrate and a resin layer disposed on the glass lens substrate, the resin layer having a diffraction grating shape, the method comprising:
 supplying a photo-curable resin material to a molding die having the diffraction grating shape including a plurality of inclined surfaces and wall surfaces;   bringing the glass lens substrate into contact with the photo-curable resin material supplied to the molding die to fill a space between the molding die and the glass lens substrate with the photo-curable resin material;   curing the photo-curable resin material by applying light in a direction substantially perpendicular to the inclined surfaces of the diffraction grating shape of the molding die or in a direction deviated from the perpendicular direction toward a thinner portion of the resin layer with respect to each inclined surface to integrate the glass lens substrate with the resin layer having the diffraction grating shape; and   releasing the glass lens substrate and the resin layer, which have been integrated together, from the molding die.   
     
     
         2 . The method according to  claim 1 , wherein the photo-curable resin material is a UV-curable resin, the light to be applied is ultraviolet light, the molding die is composed of a material that transmits ultraviolet light, and the ultraviolet light is applied through the molding die. 
     
     
         3 . The method according to  claim 1 , wherein the light application direction is determined by a lens unit disposed between a light source and the glass lens substrate and the resin layer. 
     
     
         4 . A method for manufacturing an apparatus including a first glass lens substrate, a second glass lens substrate, and a first resin layer and a second resin layer disposed and laminated between the first glass lens substrate and the second glass lens substrate, the method comprising:
 supplying a first photo-curable resin material to a molding die having a diffraction grating shape including a plurality of inclined surfaces and wall surfaces;   bringing the first glass lens substrate into contact with the first photo-curable resin material supplied to the molding die to fill a space between the molding die and the first glass lens substrate with the first photo-curable resin material;   curing the first photo-curable resin material by applying light to integrate the first glass lens substrate with the first resin layer; and   releasing the first glass lens substrate and the first resin layer, which have been integrated together, from the molding die;   supplying a second photo-curable resin material to the second glass lens substrate;   bringing the first glass lens substrate and the first resin layer, which have been integrated together, into contact with the second photo-curable resin material supplied to the second glass lens substrate to fill a space between the first resin layer and the second glass substrate with the second photo-curable resin material; and   curing the second photo-curable resin material by applying light in a direction substantially perpendicular to the inclined surfaces or in a direction deviated from the perpendicular direction toward a thinner portion of the resin layer with respect to each inclined surface to integrate the first glass lens substrate and the first resin layer with the second glass lens substrate and the second resin layer.   
     
     
         5 . The method according to  claim 4 , wherein the second resin layer is composed of a fluororesin in which fine metal particles are dispersed. 
     
     
         6 . The method according to  claim 1 , wherein the resin layer is composed of a fluororesin in which fine metal particles are dispersed. 
     
     
         7 . The method according to  claim 4 , wherein the first or the second photo-curable resin material is a UV-curable resin, the light to be applied is ultraviolet light, and the molding die is composed of a material that transmits ultraviolet light. 
     
     
         8 . The method according to  claim 4 , wherein the light application direction is determined by a lens unit disposed between a light source and, the first glass lens substrate and the first resin layer. 
     
     
         9 . The method according to  claim 4 , wherein the light application direction is determined by a lens unit disposed between a light source and the second glass lens substrate.