Patent ID: 11874217
Assignee: COMMISSARIAT A L'ENERGIE ATOMIQUE ET AUX ENERGIES ALTERNATIVES
Field: Measurement (Instruments)
Classification: CPC G | IPC G

Claim 0:
1. A device for photoacoustic characterization of a gaseous substance, the device comprising:
a light source adapted to emit a light radiation, and
a chamber intended to contain the gaseous substance to characterize, the chamber being delimited at least in part by a first wall, formed of a material at least partially transparent to said radiation, said first wall having:
an inner face, substantially flat, situated on a side of the chamber, and
an outer face, a major part of the outer face being flat, contained in a same plane, and being substantially parallel to an average plane of the inner face,

the light source being optically associated with the chamber so as to inject said light radiation into the chamber, in the form of a light beam, a part at least of the light beam being reflected on the inner face of the first wall, wherein the inner face of the first wall is etched so as to have recesses, each recess being delimited laterally by a lateral surface, a part of said lateral surface, which is illuminated by said light beam, being tilted, with respect to the average plane of said inner face, by a tilt angle a of less than 90 degrees and which satisfies the following inequality:, α
    -
    
      
        sin
        
          -
          1
        
      
      (
      
        
          sin
          ⁢
          
            
          
          ⁢
          α
        
        n
      
      )
    
  
  >
  
    i
    C
  

where ic is the critical angle of total internal reflection in said material and where n is the optical index of said material.