Optical apparatus for forming correlation spectrometers and optical processors

• US 5,905,571 A
• Filed: 08/30/1995
• Issued: 05/18/1999
• Est. Priority Date: 08/30/1995
• Status: Expired due to Term

• Current Assignee: Ahura Scientific, Inc. (Thermo Fisher Scientific Incorporated), United States Department of Energy
• Original Assignee: Sandia Corporation (Martin Marietta Corporation)
• Inventors: Butler, Michael A., Sinclair, Michael B., Senturia, Stephen D., Ricco, Antonio J.
• Primary Examiner(s): Font, Frank G.
• Assistant Examiner(s): Smith, Zandra V.
• Application Number:
  US08/522,202
• Time in Patent Office: 1,357 Days
• Field of Search: 356/326, 356/328, 356/334, 356/305, 359/375, 359/369
• US Class Current: 356/328
• CPC Class Codes: G01J 3/18 using diffraction elements, e.g. grating gratings per se G02B
• CPC Class Codes: G01J 3/457 Correlation spectrometry, e.g. of the intensity G01J3/453 takes precedence
• CPC Class Codes: G02B 26/0808 by means of one or more diffracting elements
• CPC Class Codes: G06E 3/005 using electro-optical or opto-electronic means

Abstract

Optical apparatus for forming correlation spectrometers and optical processors. The optical apparatus comprises one or more diffractive optical elements formed on a substrate for receiving light from a source and processing the incident light. The optical apparatus includes an addressing element for alternately addressing each diffractive optical element thereof to produce for one unit of time a first correlation with the incident light, and to produce for a different unit of time a second correlation with the incident light that is different from the first correlation. In preferred embodiments of the invention, the optical apparatus is in the form of a correlation spectrometer; and in other embodiments, the apparatus is in the form of an optical processor. In some embodiments, the optical apparatus comprises a plurality of diffractive optical elements on a common substrate for forming first and second gratings that alternately intercept the incident light for different units of time. In other embodiments, the optical apparatus includes an electrically-programmable diffraction grating that may be alternately switched between a plurality of grating states thereof for processing the incident light. The optical apparatus may be formed, at least in part, by a micromachining process.

Claims

1. Optical apparatus for processing incident light from a source, comprising:

(a) at least one diffractive optical element formed on a substrate and comprising a plurality of elongate grating elements within each diffractive optical element, the grating elements having a multi-periodic spaced relationship with a plurality of different periodicities and a varying height of adjacent grating elements, each diffractive optical element for a unit in time receiving and processing light; and

(b) modulation means comprising an addressing element in the form of an electro-mechanical actuator further comprising a motor coupled to a pair of the diffractive optical elements for alternately moving each of the pair of diffractive optical elements into a path of the light for receiving the light at a preselected fixed angle of incidence, thereby addressing each diffractive optical element to produce for one unit of time a first correlation with the light, and to produce for a different unit of time a second correlation with the light that is different from the first correlation.

2. Optical apparatus for processing incident light from a source comprising:

(a) at least one diffractive optical element formed on a substrate and comprising a plurality of elongate grating elements within each diffractive optical element, the grating elements having a multi-periodic spaced relationship with a plurality of different periodicities and a varying height of adjacent grating elements, each diffractive optical element for a unit in time receiving and processing light; and

(b) modulation means comprising at least one addressing element in the form of an electrostatic actuator which programs each diffractive optical element between at least two grating states thereof for addressing each diffractive optical element to produce for one unit of time a first correlation with the incident light, and to produce for a different unit of time a second correlation with the incident light that is different from the first correlation.

3. The optical apparatus in claim 2 wherein the electrostatic actuator is formed at least in part on the substrate containing each diffractive optical element.

4. The optical apparatus in claim 3 further including a plurality of electrodes on the substrate for addressing the electrostatic actuator.

5. The optical apparatus in claim 4 further including addressing circuitry on the substrate connected to the plurality of electrodes.

6. Optical apparatus for processing incident light from a source, comprising:

a plurality of pairs of diffractive optical elements in the form of an array on a substrate, each diffractive optical element comprising elongate grating elements in a multi-periodic spaced relationship with a plurality of different periodicities and a varying height of adjacent grating elements and each diffractive optical element in a particular pair for a unit in time receiving and process light;

(b) modulation means comprising light-beam deflector for addressing each diffractive optical element in the particular pair to alternately produce for one unit of time a first correlation with the incident light, and to produce for a different unit of time a second correlation with the incident light that is different from the first correlation; and

(c) selection means for selecting the particular pair of diffractive optical elements from among the array.

7. The optical apparatus in claim 6 wherein the modulation means for addressing each diffractive optical element includes at least one addressing element selected from the group consisting of electro-mechanical actuators, electrostatic actuators, and light-beam deflectors.

8. A correlation spectrometer for analyzing at least one material of interest comprising:

(a) a first diffractive optical element for intercepting and processing for one unit of time light from a source having impressed thereon a spectral response characteristic of each material of interest, the first diffractive optical element receiving the light at a preselected fixed angle of incidence and processing the light to produce a first spectrum including at least a portion of the spectral response characteristic of each material of interest;

(b) a second diffractive optical element for receiving the light at the preselected fixed angle of incidence and processing the light for a different unit of time to produce a second spectrum shifted in wavelength from the first spectrum;

(c) detector means for receiving the light and generating an output signal therefrom; and

(d) modulation means for addressing each of the diffractive optical elements for intercepting the light.

9. The correlation spectrometer in claim 8 further including signal processing means for receiving the output signal from the detector means and recovering information about each material of interest.

10. The correlation spectrometer in claim 8 wherein the first and second diffractive optical elements are formed on a common substrate.

11. The correlation spectrometer in claim 10 wherein the substrate comprises a substrate material selected from the group consisting of metals, glasses, ceramics, sapphire, diamond, fused silica, crystalline quartz, semiconductors, plastics, and epoxy resins.

12. The correlation spectrometer in claim 8 wherein at least one of the diffractive optical elements includes a light-reflective upper surface comprising a metal layer.

13. The correlation spectrometer in claim 8 wherein the modulation means includes at least one addressing element selected from the group consisting of electro-mechanical actuators, electrostatic actuators, and light-beam deflectors.

14. The correlation spectrometer in claim 13 wherein each addressing element is an electro-mechanical actuator comprising a motor coupled to each diffractive optical element for alternately moving each diffractive optical element into and out of a path of the light.

15. The correlation spectrometer in claim 13 wherein each addressing element is a light-beam deflector for coupling the light alternately to the first and second diffractive optical elements.

16. The correlation spectrometer in claim 8 further including selection means for selecting the first and second diffractive optical elements from a plurality of pairs of diffractive optical elements in the form of an array.

17. The correlation spectrometer in claim 8 wherein the plurality of pairs of diffractive optical elements forms an analysis atlas with each pair of diffractive optical elements being programmed for analysis of the spectral signature of a different preselected material of interest.

18. A correlation spectrometer for analyzing at least one material of interest by means of light from a source having impressed thereon a spectral signature due to interaction of the light with each material of interest, the correlation spectrometer comprising at least one diffractive optical element formed on a substrate and comprising within each diffractive optical element a plurality of independently addressable grating elements with adjacent adjacent grating elements being independently moveable relative to each other and configurable in at least two grating states including a first grating state selectable for an unit of time for receiving and processing the light to produce a first spectrum including at least a portion of the spectral signature of each material of interest, and a second grating state selectable for a different unit of time for receiving and processing the light to produce a second spectrum shifted in wavelength from the first spectrum.

19. The correlation spectrometer in claim 18 further including detector means for receiving the light and generating an output signal therefrom.

20. The correlation spectrometer in claim 19 further including signal processing means for receiving the output signal from the detector means and recovering information about each material of interest.

21. The correlation spectrometer in claim 18 wherein the substrate is silicon.

22. The correlation spectrometer in claim 18 further including addressing circuitry for providing a plurality of programming voltages to the grating elements for configuring the elements in at least two grating states.

23. The correlation spectrometer in claim 22 wherein the addressing circuitry is located at least in part on the substrate.

24. The correlation spectrometer in claim 22 wherein each programming voltage includes an alternating-current component having a predetermined modulation frequency.

25. A correlation spectrometer for analyzing at least one material of interest by means of light from a source having impressed thereon a spectral signature due to interaction of the light with each material of interest, the correlation spectrometer comprising:

(a) at least one diffractive optical element formed on a substrate and comprising a plurality of grating elements hinged for translatory motion, with at least one electrode on the substrate for addressing the grating elements and selecting between at least two grating states including a first grating state selectable for a unit of time for receiving and processing the light to produce a first spectrum including at least a portion of the spectral signature of each material of interest, and a second grating state being selectable for a different unit of time for receiving and processing the light to produce a second spectrum shifted in wavelength from the first spectrum.

26. The correlation spectrometer in claim 25 further including detector means for receiving the light and generating an output signal therefrom.

27. The correlation spectrometer in claim 26 further including signal processing means for receiving the output signal from the detector means and recovering information about each material of interest.

28. The correlation spectrometer in claim 25 wherein the substrate comprises a substrate material selected from the group consisting of metals, glasses, ceramics, sapphire, diamond, fused silica, crystalline quartz, semiconductors, plastics, and epoxy resins.

29. The correlation spectrometer in claim 25 wherein the substrate is silicon.

30. The correlation spectrometer in claim 25 further including addressing circuitry for providing at least one programming voltage to the diffractive optical element for selecting between the at least two grating states.

31. The correlation spectrometer in claim 30 wherein the addressing circuitry is located at least in part on the substrate.

32. The correlation spectrometer in claim 30 wherein each programming voltage includes an alternating-current component having a predetermined modulation frequency.

33. A correlation spectrometer for analyzing at least one material of interest by means of light from a source having impressed thereon a spectral signature due to interaction of the light with each material of interest, the correlation spectrometer comprising:

(a) at least one diffractive optical element formed on a substrate and comprising a plurality of grating elements hinged for angular motion of the grating elements about an axis parallel to a major axis of each of the grating elements and further having at least one electrode on the substrate for addressing the grating elements and selecting between at least two grating states thereof including a first grating state selectable for a unit of time for receiving and processing the light to produce a first spectrum including at least a portion of the spectral signature of each material of interest, and a second grating state being selectable for a different unit of time for receiving and processing the light to produce a second spectrum shifted in wavelength from the first spectrum.

34. The correlation spectrometer in claim 33 further including detector means for receiving the light and generating an output signal therefrom.

35. The correlation spectrometer in claim 34 further including signal processing means for receiving the output signal from the detector means and recovering information about each material of interest.

36. The correlation spectrometer in claim 33 wherein the substrate comprises a substrate material selected from the group consisting of metals, glasses, ceramics, sapphire, diamond, fused silica, crystalline quartz, semiconductors, plastics, and epoxy resins.

37. The correlation spectrometer in claim 33 wherein the substrate is silicon.

38. The correlation spectrometer in claim 33 further including addressing circuitry for providing at least one programming voltage to the diffractive optical element for selecting between the at least two grating states.

39. The correlation spectrometer in claim 38 wherein the addressing circuitry is located at least in part on the substrate.

40. The correlation spectrometer in claim 38 wherein each programming voltage includes an alternating-current component having a predetermined modulation frequency.