Binary optical spectrum analyzer

• US 5,461,475 A
• Filed: 02/02/1994
• Issued: 10/24/1995
• Est. Priority Date: 02/02/1994
• Status: Expired due to Fees

• Current Assignee: Physical Optics Corporation
• Original Assignee: Physical Optics Corporation
• Inventors: Chou, Hung, Lin, Shing-Hong F., Kostrzewski, Andrew, Lu, Taiwei, Lerner, Jeremy
• Primary Examiner(s): McGraw, Vincent P.
• Assistant Examiner(s): HANTIS, KAREN
• Application Number:
  US08/191,056
• Time in Patent Office: 629 Days
• Field of Search: 356/300, 356/303, 356/326, 356/328, 359/246, 359/10, 364/822
• US Class Current: 356/300
• CPC Class Codes: G01J 3/0229 using masks, aperture plates, spatial light modulators or spatial filters, e.g. reflective filters
• CPC Class Codes: G01J 3/28 Investigating the spectrum using colour filters G01J3/51

Abstract

Apparatus for analyzing a spectral signature, including: a light source; a spatial light modulator connected to the light source, the spatial light modulator modulating light from the light source in accordance with spatial features of the spectral signature; an optic system upon which modulated light from the spatial light modulator is incident, the optic system filtering the modulated light; a hologram illuminated with filtered, modulated light from the optic system, the hologram outputting an optical identification of the spectral signature; and a detector upon which the optical identification is incident, the detector detecting the optical identification.

Claims

1. Apparatus for analyzing a spectral signature, comprising:

a light source;

a spatial light modulator connected to the light source, the spatial light modulator modulating light from the light source in accordance with spatial features of the spectral signature;

an optic system upon which modulated light from the spatial light modulator is incident, the optic system filtering the modulated light;

a hologram illuminated with filtered, modulated light from the optic system, the hologram i) including a binary pattern recorded therein and ii) outputting an optical identification of the spectral signature by diffracting the filtered, modulated light through the binary pattern; and

a detector upon which the optical identification is incident, the detector detecting the optical identification.

2. The apparatus as defined in claim 1, wherein the light source includes a laser.

3. The apparatus as defined in claim 1, wherein the spatial light modulator includes a liquid crystal television.

4. The apparatus as defined in claim 1, wherein the optic system includes a 4f lens system.

5. The apparatus as defined in claim 1, wherein the hologram is a volume hologram.

6. The apparatus as defined in claim 1, wherein the detector includes a diffuser.

7. The apparatus as defined in claim 1, wherein the detector includes a diffuser and a camera monitoring the diffuser.

8. The apparatus as defined in claim 1, wherein the detector includes a detector array.

9. The apparatus as defined in claim 1, wherein the hologram includes a plurality of binary patterns recorded therein and outputting an optical identification includes outputting a plurality of optical identifications of the spectral signature by diffracting the filtered, modulated light through the plurality of binary patterns.

10. Apparatus for analyzing a spectral signature, comprising:

a laser;

a liquid crystal television connected to the laser, the liquid crystal television modulating light from the laser in accordance with spatial features of the spectral signature;

a 4f lens system upon which modulated light from the liquid crystal television is incident, the 4f lens system filtering unwanted diffraction orders from the modulated light;

a volume hologram having a focal plane, the volume hologram i) being illuminated with the filtered, modulated light from the 4f lens system, ii) including a binary pattern recorded therein and iii) outputting an optical identification of the spectral signature by diffracting the filtered, modulated light through the binary pattern;

a diffuser located at the focal plane of the hologram, the optical identification being incident upon the diffuser; and

a camera upon which light from the diffuser is incident, the camera monitoring the optical identification.

11. The apparatus as defined in claim 10, wherein an output from the camera is input to processor and compared to a reference signal.

12. The apparatus as defined in claim 10, wherein the volume hologram is prerecorded with the optical identification within an area of the volume hologram illuminated with the filtered, modulated light, the area having a shape of the spectral signature.

13. The apparatus as defined in claim 10, wherein the spectral signature is input to the liquid crystal television through a controller.

14. The apparatus as defined in claim 10, wherein the spectral signature is input to the liquid crystal television through a computer in real time.

15. The apparatus as defined in claim 10, wherein the volume hologram outputs a word to the diffuser.

16. The apparatus as defined in claim 10, wherein the volume hologram outputs a symbol to the diffuser.

17. The apparatus as defined in claim 10, wherein the hologram includes a plurality of binary patterns recorded therein and outputting an optical identification includes outputting a plurality of optical identifications of the spectral signature by diffracting the filtered, modulated light through the plurality of binary patterns.

19. The apparatus as claimed in claim 16, wherein the volume hologram outputs a spot to a location on the detector array.

18. Apparatus for analyzing a spectral signature, comprising:

a laser;

a liquid crystal television connected to the laser, the liquid crystal television modulating light from the laser in accordance with spatial features of the spectral signature;

a 4f lens system upon which modulated light from the liquid crystal television is incident, the 4f lens system filtering unwanted diffraction orders from the modulated light;

a volume hologram having a focal plane, the volume hologram i) being illuminated with the filtered, modulated light from the 4f lens system, ii) including a binary pattern recorded therein, and iii) outputting an optical identification of the spectral signature by diffracting the filtered, modulated light through the binary pattern; and

a detector array located at the focal plane of the volume hologram, the optical identification being incident upon the detector array.

20. The apparatus as defined in claim 18, wherein the volume hologram includes a plurality of binary patterns recorded therein and outputting an optical identification includes outputting a plurality of optical identifications of the spectral signature by diffracting the filtered, modulated light through the plurality of binary patterns.

21. The apparatus as defined in claim 18, wherein the liquid crystal television is controlled by a computer.

23. The apparatus defined in claim 21, wherein the identification includes a symbol.

24. The apparatus as defined in claim 21, wherein the identification includes a word.

25. The apparatus as defined in claim 21, wherein the identification includes a spot.

26. The apparatus as defined in claim 21, further comprising

a third mask connected to the first collimation optic, positionable in the path of the reference beam adjacent the volume of holographic material, having a cut-out portion representing the spatial features of a reciprocal of the spectral signature and delimiting an area of the volume of holographic material illuminated by the laser beam to a shape of the reciprocal of the spectral signature;

and

a fourth mask connected to the second collimation optic, positionable in the path of the object beam and containing a cut-out portion representing a negative identification of the spectral signature.

22. Apparatus for recording a hologram for use in an apparatus which identifies a spectral signature having spatial features, the apparatus for recording a hologram comprising:

a laser producing a laser beam;

a beam splitter connected to the laser, the beam splitter splitting the laser beam into an object beam and a reference beam, each of said object beam and said reference beam having a path;

a first collimation optic located in the path of the reference beam the first collimation optic collimating the reference beam;

a second collimation optic located in the path of the object beam the second collimation optic collimating the object beam;

a volume of holographic material located in the path of the reference beam and located in the path of the object beam;

a first mask connected to the first collimation optic, positionable in the path of the reference beam adjacent the volume of holographic material, having a cutout portion representing the spatial features of the spectral signature and delimiting an area of the volume of holographic material illuminated by the laser beam to a shape of the spectral signature;

a second mask connected to the second collimation optic, positionable in the path of the object beam and containing a cut-out portion representing an identification of the spectral signature; and

a diffuser adjacent the second mask which diffuses light passing through the cut-out portion of the second mask,

whereby the volume of holographic material is recorded with an interference between the object beam and reference beam such that an identification is recorded in the volume of holographic material within an area in the shape of the spectral signature.

27. A method of analyzing a spectral signature of a constituent, comprising:

acquiring the spectral signature of the constituent;

modulating light from a laser light source in accordance with spatial features of the spectral signature of the constituent;

filtering the modulated light;

illuminating an area of a hologram in accordance with spatial features of the spectral signature with the filtered and modulated light, said hologram including a binary pattern recorded therein;

outputting an optical identification symbol from the hologram by diffracting the filtered and modulated light through the binary pattern; and

detecting the optical identification symbol.

28. The method of claim 27, wherein outputting an optical identification includes outputting a plurality of identification symbols from the hologram.