SPECTROSCOPIC SYSTEM

• US 20090040516A1
• Filed: 08/10/2007
• Published: 02/12/2009
• Est. Priority Date: 08/10/2007
• Status: Abandoned Application

• Current Assignee: Honeywell International Inc.
• Original Assignee: Honeywell International Inc.
• Inventors: Wang, Tzu-Yu, Fritz, Bernard S., Krafthefer, Brian C., Cox, James A., Bauhahn, Paul E.
• Application Number:
  US11/837,359
• Publication Number:
  US 20090040516A1
• Time in Patent Office: Days
• US Class Current: 356/301
• CPC Class Codes: G01J 3/02 Details
• CPC Class Codes: G01J 3/021 using plane or convex mirrors, parallel phase plates, or particular reflectors
• CPC Class Codes: G01J 3/0229 using masks, aperture plates, spatial light modulators or spatial filters, e.g. reflective filters
• CPC Class Codes: G01J 3/4412 Scattering spectrometry particle sizing by light scattering G01N15/0205; optical velocimetry of particles G01P5/20, G01P5/26

Abstract

A spectroscopic system having a coded aperture as a gating device. Light of a Raman scattering may enter the system and encounter a mask gate. The mask may have a matrix of micro mirrors some of which pass light on to a diffraction grating when the gate is on. Some of the mirrors will not pass on light thereby resulting in coded light to the grating. If the gate is off, then no light is passed on to the grating. The grating may pass the coded and spectrally spread light on to a detector array. The array signals representing the light on the array may go to a processor so one can obtain information about the target that emanated the Raman scatter when impinged by a light beam.

Claims

1. A spectrometer system comprising:

a light gate;

an optical grating proximate to the light gate; and

a detector array proximate to the grating.

2. The system of claim 1, wherein the light gate comprises:

an array of mirrors; and

wherein;

at least some of the mirrors of the array have an on position and an off position;

a mirror in an on position can reflect incoming light to the grating; and

a mirror in an off position cannot reflect incoming light to the grating.

3. The system of claim 2, wherein the array of mirrors is a reflective mask to incoming light.

4. The system of claim 3, wherein the reflective mask has an encoding pattern when at least some of the mirrors are in an on position.

5. The system of claim 4, wherein the pattern has a form of a Hadamard S-matrix.

6. The system of claim 4, wherein the pattern is a 2-dimensional pattern.

7. The system of claim 6, wherein:

the light gate is for passing certain light to the grating and blocking other light from the grating; and

the certain light is light scattered from a sample by a light source.

8. The system of claim 1, wherein:

the light gate is for passing certain light to the grating and blocking other light from the grating; and

the certain light is Ram an scattered light.

9. The system of claim 8, further comprising:

a filter for blocking light having a wavelength shorter than a wavelength of the certain light, from the light gate; and

a filter for blocking light having a wavelength longer than the certain light, from the detector array.

10. The system of claim 7, wherein:

the light gate is a coded aperture; and

the light received by the detector array is decoded for obtaining spectral information about the certain light.

11. The system of claim 10, wherein the coded aperture is a digital micromirror device.

12. A spectrometric analyzer comprising:

a gating device;

a diffraction device proximate to the gating device; and

a detector array proximate to the diffraction device; and

wherein the gating device is a coded aperture.

13. The analyzer of claim 12, wherein the coded aperture is a digital micromirror device.

14. The analyzer of claim 12, wherein:

the coded aperture has a mask;

the mask has a plurality of pixels;

each pixel a first position and a second position;

the first position conveys light received by the pixel to the diffraction device;

the second position prevents light received by the pixel from going to the diffraction device;

when the gating device is on, the mask is encoded with some pixels in a first position and some pixels, if any, in a second position; and

when the gating device is off, the mask should have no pixels in the first position.

15. The analyzer of claim 14, wherein the mask is encoded with a Hadamard S-matrix.

16. The analyzer of claim 15, wherein:

the gating device is on upon receipt of Raman scattered light; and

the gating device is off when not in receipt of Raman scattered light.

17. The analyzer of claim 16, further comprising:

a first filter for light going to the gating device; and

a second filter for light going from the diffraction device to the detector array; and

wherein;

the first filter is for passing light only having a wavelength about the same or longer than the wavelength of Raman scattering; and

the second filter is for passing light only having a wavelength about the same or shorter than the wavelength of the Raman scattering.

18. A method for spectroscopy comprising:

receiving scattered light;

focusing the light on a coded aperture gate;

opening the gate for light that is Raman scattered light from a sample impinged by light from a light source;

closing the gate as soon as the Raman scattered light is no longer received; and

letting the light be directed by the open gate to a diffractive device to be diffracted according to wavelength on a detector array.

19. The method of claim 18, wherein:

the coded aperture gate is an array of a plurality of mirrors;

each mirror can swivel between a first position and a second position;

in the first position, a mirror reflects impinging light to the diffractive device;

in the second position, a mirror reflects impinging light to a light dump;

for an open gate, each mirror is in either open position or a closed position; and

for a closed gate each mirror is in a closed position.

20. The method of claim 19, wherein when the gate is open, the light is reflected as encoded light according to the mirrors'"'"' positions.