Spectral analyzer with new high efficiency collection optics and method of using same

Abstract

A spectral analyzer has a high efficiency optical collector having a first concave reflector portion and an opposed second concave reflector portion providing an exit passage therethrough, and a light emitting source of a predetermined wavelength range is positioned in the collector so that the light is collected and directed to the exit passage. A specimen holder is positioned adjacent the exit passage and has windows at its entrance and exit ends. An elongated reverse non-imaging optical member which has a peripheral wall reflecting light rays entering through the exit window of the holder reduces the angle of the rays relative to the optical axis of the optical member as they pass therethrough. The light passing through the exit end of the optical member enters a detector assembly including at least one photo detector sensitive to a predetermined wavelength of light, and at least one optical filter disposed between the optical member and the photodetector to pass light of the predetermined wavelength.

Having thus described in the invention, what is claimed is: 
     
       1. A spectral analyzer comprising: (a) a high efficiency optical collector having a first concave reflector portion and an opposed second concave reflector portion, said second reflector portion having an exit passage therethrough;   (b) a source for light emitting of a predetermined wavelength range positioned in said collector so that the emitted light is collected and directed by said reflector portions to said exit passage;   (c) a specimen holder positioned adjacent said exit passage of said collector and having entrance and exit ends;   (d) an elongated non-imaging optical member having its entrance end at the exit end of said specimen holder and having an exit end, said member having a peripheral wall reflecting light rays entering through the exit end of said holder to reduce the angle of the rays relative to the optical axis of said optical member as they pass therethrough; and   (e) a detector assembly at the exit end of said optical member including at least one photodetector sensitive to a predetermined wavelength of light and at least one optical filter disposed between said optical member and said detector to pass light of said predetermined wavelength.   
     
     
       2. The spectral analyzer in accordance with claim 1 wherein said second portion of said collector is a concave spherical surface. 
     
     
       3. The spectral analyzer in accordance with claim 1 wherein said first portion of said collector is a concave spherical surface. 
     
     
       4. The spectral analyzer in accordance with claim 1 wherein said first portion of said collector is an ellipsoidal surface. 
     
     
       5. The spectral analyzer in accordance with claim 1 wherein said non-imaging optical member has a compound parabolic configuration. 
     
     
       6. The spectral analyzer in accordance with claim 1 wherein said non-imaging optical member has a configuration selected from the group consisting of conical, generally aspherical and spline. 
     
     
       7. The spectral analyzer in accordance with claim 1 wherein said entrance and exit ends of said specimen holder have windows therein to filter light rays to pass those of a predetermined wavelength range. 
     
     
       8. The spectral analyzer in accordance with claim 1 wherein said detector assembly includes an optical concentrator between said filter and said photodetector. 
     
     
       9. The spectral analyzer in accordance with claim 1 wherein a multiplicity of cooperating photodetectors and a multiplicity of cooperating filters sensitive to light rays of different wavelength ranges are provided in said detector assembly. 
     
     
       10. The spectral analyzer in accordance with claim 1 wherein said specimen holder provides a chamber for receiving the specimen and through which the light rays will pass. 
     
     
       11. The spectral analyzer in accordance with claim 1 wherein said specimen holder includes means for supporting a translucent solid specimen. 
     
     
       12. The spectral analyzer in accordance with claim 1 wherein said specimen holder includes means for locating the surface of a specimen at an angle to the longitudinal axis of said holder. 
     
     
       13. The spectral analyzer in accordance with claim 1 wherein said specimen holder is a solid translucent light guide which permits evanescent spectral energy absorption at the interface with a specimen disposed on its periphery. 
     
     
       14. The spectral analyzer in accordance with claim 1 wherein there is included a chopper to pulse the light rays passing into said specimen holder from said collector. 
     
     
       15. The spectral analyzer in accordance with claim 1 wherein said light source emits light rays in the infrared wavelength. 
     
     
       16. The spectral analyzer in accordance with claim 1 wherein said light source includes means for pulsing said source. 
     
     
       17. The spectral analyzer in accordance with claim 1 wherein said light emitting source emits light of a broad range of wavelength range. 
     
     
       18. In a method for spectral analysis, the steps comprising: (a) providing a source of light of a predetermined wavelength range within a collector having opposed concave reflective surfaces;   (b) providing power to said light source to effect emission of light rays;   (c) collecting and reflecting said light rays to an exit aperture from said collector and into a specimen holder containing a specimen to be analyzed, said specimen interacting with said light rays to provide a spectral indicia of components therein;   (d) passing the light rays through an elongated non-imaging optical member to reduce the angle of the light rays entering thereinto relative to the optical axis of said member;   (e) directing the light rays exiting said optical member onto a photodetector to generate signals indicative of a component of said specimen; and   (f) analyzing said signals from said photodetector.   
     
     
       19. The method of spectral analysis in accordance with claim 18 wherein said light rays exiting said optical member are directed through a filter prior to impinging upon said photodetector. 
     
     
       20. The method of spectral analysis in accordance with claim 18 wherein said light rays exiting said optical member are directed through an optical concentrator prior to said photodetector. 
     
     
       21. The method of spectral analysis in accordance with claim 18 wherein windows are provided at the entrance and exit ends of said specimen holder to filter the light rays passing therethrough. .Iadd. 
     
     
       22.  A spectral analyzer comprising: (a) a source of light capable of emitting a predetermined wavelength range directed to an exit passage;   (b) a specimen holder positioned adjacent said exit passage having entrance and exit ends;   (c) an elongated non-imaging member having its entrance end at the exit end of said specimen holder and having an exit end, said elongated member having a peripheral wall adapted to reflect light rays emitted from said exit end of said specimen holder to reduce the angle of such rays relative to the optical axis of said elongated member as said light rays pass therethrough; and   (d) a detector assembly at said exit end of said elongated member including at least one photodetector sensitive to a predetermined wavelength of light and at least one optical filter disposed between said elongated member and said detector assembly adapted to pass light of said predetermined wavelength. .Iaddend..Iadd.23. In a method for spectral analysis, the steps comprising:   (a) providing a source of light of a predetermined wavelength range;   (b) providing power to said light source to effect emission of light rays into a specimen holder containing a specimen to be analyzed, said specimen interacting with said light rays to provide a spectral indicia of components therein;   (c) directing the light rays exiting said specimen holder through an elongated non-imaging member adapted to reflect said light rays to reduce their angle relative to the optical, axis of elongated member and onto a photodetector to generate signals indicative of a components of said specimen; and   (d) analyzing said signals from said photodetector. .Iaddend.