Horticultural sensor

Abstract

A gas sensing system having a networked web of gas sensors having an ability to detect a chemical species in a gas sensor has a beam emitter that emits a first beam comprising laser, a beam-splitting interferometer, a spectrometer and a detector, wherein the first beam is to strike the gas that produces a second beam comprising a Raman signal, the beam-splitting interferometer is to create a phase delay in the second beam is disclosed. The gas sensing system could be used for spectroscopic detection of ethylene by generating a first beam comprising laser, striking the first beam to a gas comprising ethylene 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 a Raman signature of ethylene. The gas sensing system could be used for the determination of the extent of ripening in a specific field area.

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 gas sensing system comprising a networked web of gas sensors having an ability to detect a chemical species in a gas, wherein said gas sensor comprises a beam emitter that emits a first beam comprising a laser, a beam-splitting interferometer, a spectrometer and a detector, wherein said first beam strikes the gas that produces a second beam comprising a Raman signal, said beam-splitting interferometer creates a phase delay in the second beam, and said phase delay providing information on overlapping Raman signals.

2. The gas sensing system of claim 1, wherein the chemical species is ethylene.

3. The gas sensing system of claim 1, further comprising optical elements to collect the second beam and concentrate the second beam.

4. The gas sensing system of claim 1, wherein the spectrometer comprises diffraction gratings.

5. The gas sensing system of claim 1, further comprising a microprocessor, wherein the microprocessor contains a library of Raman spectra.

6. The gas sensing system of claim 5, wherein the detector is an array detector.

7. The gas sensing system of claim 1, wherein the detector is a charge coupled device, a transducer or a photodiode.

8. The gas sensing system of claim 1, further comprising a sample collection device.

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

10. The gas sensing system 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 ethylene, comprising generating a first beam comprising laser, striking the first beam to a gas comprising ethylene 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 a Raman signature of ethylene.

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 a detector by the spectrometer.

15. The method of claim 14, wherein the 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 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 detector.

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

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

20. A method for determining the extent of ripening in a specific field area, comprising generating a first beam comprising laser, striking the first beam in the specific field area, wherein the field area comprises ethylene, 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 analyzing the Raman signal of the second beam by an analyzer, wherein the analyzer maps the extent of ripening in the specific field area as a function of the ethylene concentration in the specific field area.