Tuned dynamic eigen spectroscopy systems
First Claim
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1. An apparatus for detecting gas concentrations, the apparatus comprising:
- a coded filter to oscillate at a selected frequency;
a photo detector positioned below the coded filter such that the coded filter selectively blocks light that is directed at the photo detector;
optics for projecting spectral information on to the coded filter; and
a processor for analyzing a signal received from the photo detector, wherein the processoris adapted to weight harmonics of the signal, wherein the slits are positioned to pass at least two AC components of the spectrally separated light corresponding to a gas not of interest such that the AC components cancel out on the photo detector.
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Abstract
An apparatus for detecting gas concentrations includes a coded filter to oscillate proximate a resonant frequency. A photo detector is positioned below the coded filter such that the coded filter selectively blocks light that is directed at the photo detector. Optics are positioned to project spectral information on to the coded filter. A processor analyzes a signal received from the photo detector. The processor is adapted to weight a harmonic attic signal.
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Citations
19 Claims
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1. An apparatus for detecting gas concentrations, the apparatus comprising:
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a coded filter to oscillate at a selected frequency; a photo detector positioned below the coded filter such that the coded filter selectively blocks light that is directed at the photo detector; optics for projecting spectral information on to the coded filter; and a processor for analyzing a signal received from the photo detector, wherein the processor is adapted to weight harmonics of the signal, wherein the slits are positioned to pass at least two AC components of the spectrally separated light corresponding to a gas not of interest such that the AC components cancel out on the photo detector. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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8. A device for detecting gas concentrations comprising:
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a movable coded filter having multiple slits in a proof mass; an optical element positioned to receive gas filtered light and spectrally separate the gas filtered light onto the coded filter wherein spectral bands run in the same direction as the slits, the slits positioned to cancel AC signals corresponding to at least one gas not of interest; a photo detector positioned to receive the spectrally separated light through the oscillating slits in the moveable coded filter to provide an AC signal representative of a selected gas; and a controller coupled to receive the AC signal, convert the AC signal to a digital signal, to weight a harmonic of the received AC signal, and to correlate an amplitude of the AC signal with the weighted harmonic to a concentration of the selected gas. - View Dependent Claims (9, 10, 11, 12, 13, 14)
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15. A method for detecting a gas, the method comprising:
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receiving light from a light source through a plume of gas; spectrally separating the light; oscillating a coded filter to selectively pass portions of the spectrally separated light onto a single photo detector; detecting an AC signal via the single photo detector representative of a gas of interest; weighting a harmonic of the AC signal; and combining the AC signal with the weighted harmonic of the AC signal to detect the gas, wherein the coded filter is configured to pass at least two AC components of the spectrally separated light corresponding to a gas not of interest such that the AC components cancel out on the photo detector. - View Dependent Claims (16, 17, 18, 19)
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Specification