SPECTROMETER DESIGNS

• US 20080239492A1
• Filed: 01/29/2008
• Published: 10/02/2008
• Est. Priority Date: 05/27/2005
• Status: Active Grant

• Current Assignee: Corning Incorporated
• Original Assignee: Innovative Technical Solutions, Inc. (Corning Incorporated)
• Inventors: Warren, Chris P.
• Granted Patent: US 7,898,660 B2
• Time in Patent Office: Days
• US Class Current: 359/570
• CPC Class Codes: G01J 3/02 Details
• CPC Class Codes: G01J 3/0205 Optical elements not provided otherwise, e.g. optical manifolds, diffusers, windows
• CPC Class Codes: G01J 3/0208 using focussing or collimating elements, e.g. lenses or mirrors; performing aberration correction
• CPC Class Codes: G01J 3/0259 Monolithic
• CPC Class Codes: G01J 3/0291 Housings; Spectrometer accessories; Spatial arrangement of elements, e.g. folded path arrangements
• CPC Class Codes: G01J 3/18 using diffraction elements, e.g. grating gratings per se G02B
• CPC Class Codes: G01J 3/2823 Imaging spectrometer

Abstract

Various embodiments include spectrometers comprising diffraction gratings monolithically integrated with other optical elements. These optical elements may include slits and mirrors. The mirrors and gratings may be curved. In one embodiment, the mirrors are concave and the grating is convex. The mirrors and grating may be concentric or nearly concentric.

Claims

1. A spectrometer comprising:

a body comprising a mass of substantially optically transmissive material;

a first reflector;

a curved reflective grating, said first reflector and said curved reflective grating defining a first optical path therebetween, said first reflector and said reflective grating disposed with respect to said body such that said first optical path substantially comprises said substantially transmissive material; and

a detector defining a second optical path extending from said curved reflective grating to said detector, said second optical path substantially comprising said substantially transmissive material.

2. The spectrometer of claim 1, further comprising a second reflector disposed in said second optical path from said curved grating to said detector such that light diffracted from said curved reflective grating is reflected from said second reflector to said detector.

3. The spectrometer of claim 2, wherein said first and second reflectors have a concave curvature defined by substantially equal radii of curvature and substantially concentric centers of curvature.

4. The spectrometer of claim 3, wherein said reflective grating has a convex curvature defined by a radius of curvature that is about one-half that of said radii of curvature for said first and second reflectors and has a center of curvature that is substantially concentric with said first and second reflectors.

5. The spectrometer of claim 1, further comprising a slit, light passing through said slit propagating to said first reflector and along said first optical path to said curved grating.

6. The spectrometer of claim 1, wherein said substantially transmissive material comprises fused silica.

7. The spectrometer of claim 1, wherein said first reflector is disposed on a surface of said body.

8. The spectrometer of claim 1, wherein said reflective grating is disposed on a surface of said body.

9. The spectrometer of claim 1, wherein said reflective grating has a convex curvature facing said first and second optical paths.

10. The spectrometer of claim 1, wherein said first optical path has an optical path length between about 1 centimeters and 5 centimeters.

11. The spectrometer of claim 1, wherein said body has a width between about 5 centimeters and 10 centimeters.

12. The spectrometer of claim 1, wherein said detector comprises a two-dimensional CMOS detector array, a two-dimensional CCD detector array, a two-dimensional HgCdTe detector array, or a two-dimensional InSb detector array.

13. A spectrometer comprising:

a body comprising a mass of substantially optically transmissive material;

a first curved reflector; and

a reflective grating, said first curved reflector and said reflective grating defining a first optical path therebetween, said first curved reflector and said reflective grating disposed with respect to said body such that said first optical path substantially comprises said substantially transmissive material,

wherein said reflective grating is configured to reflect broadband light having a bandwidth of at least about 400 nanometers to a detector via a second optical path comprising said substantially transmissive material.

14. The spectrometer of claim 13, further comprising said detector.

15. The spectrometer of claim 13, further comprising a second reflector disposed in said second optical path from said reflective grating to said detector such that light diffracted from said reflective grating is reflected from said second reflector to said detector.

16. The spectrometer of claim 15, wherein said first and second reflectors are concave and have a curvature defined by a first sphere, said reflective grating is convex and has a curvature defined by a second sphere, and said first and second spheres are substantially concentric and the radius of said first circle is approximately twice that of said second circle.

17. The spectrometer of claim 13, further comprising a slit, light passing through said slit propagating to said first curved reflector and along said first optical path to said grating.

18. The spectrometer of claim 13, wherein said first curved reflector is disposed on a surface of said body.

19. The spectrometer of claim 13, wherein said reflective grating is disposed on a surface of said body.

20. The spectrometer of claim 13, further comprising a second curved reflector, said first and second curved reflectors defined by substantially same centers and radii of curvature, said reflective grating having a curvature defined by a center of curvature substantially concentric with said centers of curvature of said first and second curved reflectors and having a radius of curvature about one-half the radii of curvature of said first and second curved reflectors.

21. A spectrometer comprising:

a first body portion comprising substantially optically transmissive material;

first and second reflective regions disposed on a first side of said first body portion; and

a reflective grating disposed on a second side of said first body portion;

wherein said first and second reflective portions and said reflective grating are arranged with respect to each other such that broadband light at least about 300 nanometers in bandwidth propagating through said substantially optically transmissive material incident on said first reflective region is reflected to said grating, diffracted from said grating through said substantially optically transmissive material to said second reflective portion, and reflected from said second reflective portion through said optically transmissive material.

22. The spectrometer of claim 21, further comprising a slit, light passing through said slit propagating to said first reflective region.

23. A spectrometer comprising:

a medium comprising substantially optically transmissive material;

a slit; and

a reflective grating, said slit and said reflective grating defining a first optical path therebetween, said slit and said reflective grating disposed with respect to each other and said medium such that said first optical path substantially comprises said substantially transmissive material.

24. The spectrometer of claim 23, further comprising a reflector disposed in said first optical path from said slit to said reflective grating such that light propagating though said slit is reflected from said reflector to said reflective grating.

25. The spectrometer of 23, further comprising a detector in a second optical path extending from said reflective grating to said detector, said second optical path substantially comprising said substantially transmissive material.

26. The spectrometer of claim 25, further comprising a reflector disposed in said second optical path from said reflective grating to said detector such that light diffracted from said grating is reflected from said grating to said detector.

27. A spectrometer configured to be mounted in an unmanned airborne vehicle, the spectrometer comprising:

a body comprising a mass of substantially optically transmissive material;

a first reflector;

a reflective grating, said first reflector and said reflective grating defining a first optical path therebetween, said first reflector and said reflective grating disposed with respect to said body such that said first optical path substantially comprises said substantially transmissive material, said reflective grating being configured to reflect light to a detector via a second optical path comprising said substantially transmissive material; and

a housing in which said body, said first reflector, and said reflective grating are positioned, wherein said housing is no greater than 1000 cubic centimeters, and said housing is configured to be mounted in an unmanned airborne vehicle receiving area.

28. The spectrometer of claim 27, wherein said first reflector is curved.

29. The spectrometer of claim 27, further comprising said detector.

30. The spectrometer of claim 27, further comprising a second reflector disposed in said second optical path from said reflective grating to said detector such that light diffracted from said reflective grating is reflected from said second reflector to said detector.

31. The spectrometer of claim 30, wherein said second reflector has a substantially same curvature as said first reflector defined by a radius and center of curvature.

32. The spectrometer of claim 31, wherein said grating is curved and has a center of curvature substantially concentric with said center of curvature of said first and second reflections and a radius of curvature that is about one half the radius of curvature of said first and second reflectors.

33. The spectrometer of claim 27, wherein said spectrometer weighs no more than 2 pounds.

34. The spectrometer of claim 27, wherein said spectrometer is configured to operate with light having a wavelength within the range of between about 400-1000 nanometers.

35. The spectrometer of claim 27, wherein said spectrometer has a minimum spectral resolution of less than about 5 nanometers.

36. The spectrometer of claim 27, further comprising a slit, light passing through said slit propagating to said first reflector and along said first optical path to said reflective grating.

37. The spectrometer of claim 27, wherein said first reflector is disposed on a surface of said body.

38. The spectrometer of claim 27, wherein said reflective grating is disposed on a surface of said body.