Optical Element

Abstract

An optical element according to the present invention is an optical element including: a first light transmitting layer having a first sawtooth blazed surface 10, the first light transmitting layer including a plurality of first light-transmitting slopes 12 defining a first blaze angle α; and a second light transmitting layer having a second sawtooth blazed surface 20 including a plurality of second light-transmitting slopes 22 defining a second blaze angle β, the second light transmitting layer being in contact with the first sawtooth blazed surface 10 of the first light transmitting layer. A tilting direction of the first light-transmitting slope 12 and a tilting direction of the second light-transmitting slope 22 are opposite.

1 . An optical element comprising: 
 a first light transmitting layer having a first sawtooth blazed surface, the first sawtooth blazed surface including a plurality of first light-transmitting slopes defining a first blaze angle;    a second light transmitting layer having a second sawtooth blazed surface including a plurality of second light-transmitting slopes defining a second blaze angle, the second light transmitting layer being in contact with the first sawtooth blazed surface of the first light transmitting layer, wherein,    a tilting direction of the first light-transmitting slopes and a tilting direction of the second light-transmitting slopes are opposite.    
     
     
         2 . The optical element of  claim 1 , wherein the first light transmitting layer has a lens shape.  
     
     
         3 . The optical element of  claim 1 , further comprising a lens-shaped member, wherein, 
 the first light transmitting layer is supported by the lens-shaped member.    
     
     
         4 . The optical element of  claim 1 , wherein the first light-transmitting slopes on the first sawtooth blazed surface are arranged with an arraying pitch which varies with position on the first light transmitting layer.  
     
     
         5 . The optical element of  claim 1 , wherein, 
 when the first light transmitting layer has a refractive index n; the second light transmitting layer has a refractive index n′; the first sawtooth blazed surface has a step height d; the second sawtooth blazed surface has a step height d′; and light being used has an average wavelength λ,    {d′(n′−1)−d(n−n′)}/λ is within a range of ±0.2 around an integer value.    
     
     
         6 . The optical element of  claim 1 , wherein, 
 when the first light transmitting layer has an Abbe number Ξ; the second light transmitting layer has an Abbe number ν′; the first sawtooth blazed surface has a step height d; and the second sawtooth blazed surface has a step height d′,    the relationship d′/d<ν′/ν−1 is satisfied.    
     
     
         7 . The optical element of  claim 1 , wherein a refractive index and dispersion of the first light transmitting layer are higher than a refractive index and dispersion of the second light transmitting layer.  
     
     
         8 . The optical element of  claim 1 , wherein an amount of offset δ between an arbitrary one of the plurality of first light-transmitting slopes and the second light-transmitting slope through which light having been transmitted through the first light-transmitting slope is transmitted is 5% or less of an arraying pitch Λ of the first light-transmitting slope where the first light-transmitting slope is positioned.  
     
     
         9 . The optical element of  claim 1 , wherein, when a pitch of the first sawtooth blazed surface is expressed as m×Λ, a pitch of the second sawtooth blazed surface is expressed as n×Λ, each of m and n being an integer of 1 or more.  
     
     
         10 . An optical element comprising: 
 a first light transmitting layer having a first sawtooth blazed surface, the first sawtooth blazed surface including a plurality of first light-transmitting slopes defining a first blaze angle;    a second light transmitting layer having a second sawtooth blazed surface including a plurality of second light-transmitting slopes defining a second blaze angle, the second light transmitting layer being in contact with the first sawtooth blazed surface of the first light transmitting layer, wherein,    when p and q are integers of different signs other than zero,    80% or more of light which is transmitted through the first light transmitting layer is diffracted as p th -order light; and    80% or more of light which is transmitted through the second light transmitting layer is diffracted as p th -order light.    
     
     
         11 . The optical element of  claim 10 , wherein, 
 when the first light transmitting layer has an Abbe number ν; the second light transmitting layer has an Abbe number ν′; the first sawtooth blazed surface has a step height d; and the second sawtooth blazed surface has a step height d′,    the relationship d′/d<ν′/ν−1 is satisfied.    
     
     
         12 . The optical element of  claim 10 , wherein a refractive index and dispersion of the first light transmitting layer are higher than a refractive index and dispersion of the second light transmitting layer.  
     
     
         13 . The optical element of  claim 10 , wherein the relationship p+q=1 is satisfied.  
     
     
         14 . The optical element of  claim 10 , wherein, 
 when the first light transmitting layer has a refractive index n; the second light transmitting layer has a refractive index n′; the first sawtooth blazed surface has a step height d; the second sawtooth blazed surface has a step height d′; and light being used has an average wavelength λ,    the relationship 0.7λ<|(n−n′)d/p|<1.2λ; and    the relationship 0.7λ<|(n′−1)d′/q|<1.2λ are satisfied.    
     
     
         15 . The optical element of  claim 10 , wherein an amount of offset δ of the second sawtooth blazed surface with respect to the first sawtooth blazed surface is 5% or less of a pitch Λ of the first sawtooth blazed surface.  
     
     
         16 . The optical element of  claim 10 , wherein, when a pitch of the first sawtooth blazed surface is expressed as m×Λ, a pitch of the second sawtooth blazed surface is expressed as n×Λ, each of m and n being an integer of 1 or more.