Patent ID: 11892438
Assignee: ASAHI KASEI MICRODEVICES CORPORATION
Field: Measurement (Instruments)
Classification: CPC G | IPC G

Claim 16:
17. The optical densitometer according to claim 15, wherein
a material forming a separation portion between the substrate and the diffraction grating regions has a refractive index smaller than a refractive index of the substrate, and
the distance L1 between the diffraction grating region and the substrate satisfies the following Expression (6):, (
                  
                    
                      2
                      ⁢
                      m
                    
                    -
                    1
                  
                  )
                
                ⁢
                
                  λ
                  0
                
              
              -
              
                4
                ⁢
                
                  n
                  gr
                
                ⁢
                
                  t
                  gr
                
              
            
            
              4
              ⁢
              
                n
                
                  L
                  ⁢
                  
                    
                  
                  ⁢
                  1
                
              
            
          
          -
          
            
              3
              ⁢
              
                λ
                0
              
            
            
              16
              ⁢
              
                n
                
                  L
                  ⁢
                  
                    
                  
                  ⁢
                  1
                
              
            
          
        
        ≤
        
          L
          ⁢
          
            
          
          ⁢
          1
        
        ≤
        
          
            
              
                
                  (
                  
                    
                      2
                      ⁢
                      m
                    
                    -
                    1
                  
                  )
                
                ⁢
                
                  λ
                  0
                
              
              -
              
                4
                ⁢
                
                  n
                  gr
                
                ⁢
                
                  t
                  gr
                
              
            
            
              4
              ⁢
              
                n
                
                  L
                  ⁢
                  
                    
                  
                  ⁢
                  1
                
              
            
          
          +
          
            
              3
              ⁢
              
                λ
                0
              
            
            
              16
              ⁢
              
                n
                
                  L
                  ⁢
                  
                    
                  
                  ⁢
                  1
                
              
            
          
        
      
    
    
      
        Expression
        ⁢
        
          
        
        ⁢
        
          (
          6
          )
        
      
    
  

where λ0 represents the average wavelength, in vacuum, of the light propagating through the core layer, nL1 represents a refractive index of a material forming the separation portion between the substrate and the diffraction grating region, tgr represents an effective film thickness of the diffraction grating region of the diffraction grating portion, ngr represents a refractive index of a material forming the diffraction grating region of the diffraction grating portion, and m is a natural number.