Optochemical sensor

Abstract

A sensor containing a beam emitter that emits a first beam having laser, a beam-splitting interferometer and an array detector, wherein the first beam is to strike a sample that produces a second beam comprising a Raman signal, the beam-splitting interferometer is to create a phase delay in the second beam, and the array detector comprises a plurality of detectors is disclosed. The sensor could be used for spectroscopic detection of a sample by generating a first beam comprising laser, striking the first beam to a sample to produce a second beam comprising a Raman signal, creating a phase delay in the second beam and detecting the Raman signal of the second beam. The uses of the sensor include detection of biological and chemical warfare agents, narcotics, among others for homeland security.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows representative Raman signals to distinguish chemical variants having a common structural backbone.

FIG. 2 shows representative Raman signals showing where different chemical variants have overlapping Raman peaks.

FIG. 3 shows transmittance spectrum of long and short wave pass edge filters.

FIG. 4 shows an embodiment of the Raman lidar based optical sensor.

FIG. 5 shows an embodiment of an array detector.

FIG. 6 shows the mechanism of beam splitting by a beam-splitting interferometer.

Claims

1. A sensor comprising a beam emitter that emits a first beam comprising laser, a beam-splitting interferometer, a spectrometer and an array detector comprising a plurality of detectors, wherein the first beam is to strike a sample that produces a second beam comprising a Raman signal, said beam-splitting interferometer creates a phase delay in the second beam, wherein said phase delay provides information on overlapping Raman signals.

2. The sensor of claim 1, further comprising optical elements to collect the second beam and concentrate the second beam.

3. The sensor of claim 1, further comprising an edge filter.

4. The sensor of claim 1, wherein the spectrometer comprises diffraction gratings.

5. The sensor of claim 1, further comprising a microprocessor.

6. The sensor of claim 5, wherein the microprocessor contains a library of Raman spectra.

7. The sensor of claim 1, wherein the array detector comprises a detector which is a charge coupled device, a transducer or a photodiode.

8. The sensor of claim 1, further comprising a sample collection device.

9. The sensor of claim 1, wherein the interferometer comprises an optical bench, a wafer having optical structures, an optical splitter or an optical waveguide.

10. The sensor of claim 9, wherein the optical splitter or the optical waveguide comprises optical fibers coupled to each other to form the optical splitter or the optical guide.

11. A method for spectroscopic detection of a sample, comprising generating a first beam comprising laser, striking the first beam to a sample to produce a second beam comprising a Raman signal, creating a phase delay in the second beam, passing the second beam through a spectrometer and detecting the Raman signal of the second beam.

12. The method of claim 11, further comprising permitting transmission of the Raman signal of the second beam through a filtering device that substantially rejects non-Raman signals of the second beam.

13. The method of claim 11, wherein the second beam is modified to substantially exclude all IR signals and include substantially only the Raman signal.

14. The method of claim 11, further comprising spreading the Raman signal onto an array detector by the spectrometer.

15. The method of claim 14, wherein the array detector has a sensitivity to resolve overlapping Raman signals having a Raman scattering cross-section as low as about 10−29 cm2/molecule.

16. The method of claim 15, further comprising analyzing an output of the array detector.

17. The method of claim 16, further comprising comparing Raman spectra stored in a library to a Raman spectrum from an output of the array detector.

18. The method of claim 11, further comprising collecting the sample in a sample collection device.

19. The method of claim 11, wherein the sample is at a distance of greater than 30 meters from the array detector.

20. A method of manufacturing a sensor, comprising locating (a) a beam emitter that emits a first beam comprising laser, (b) a beam-splitting interferometer, (c) a spectrometer and (d) a detector within the sensor in a manner such that the first beam strikes a sample and produces a second beam comprising a Raman signal, and the beam-splitting interferometer creates a phase delay in the second beam.