Range gated remote measurement utilizing two-photon absorption
First Claim
1. Apparatus for making remote atomic absorption measurements comprising:
- means, including two collimated counter-propagating beams of coherent energy, for establishing two-photon absorption in the earth'"'"'s atmosphere at a number of selectable locations along the direction of said beams, and, means for measuring a two-photon absorption related characteristic of one of said beams after said one beam has participated in establishing two-photon absorption at a selected location.
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Abstract
Two-photon absorption measurements are made at various points remote from monitoring apparatus by apparatus which includes two lasers that produce counter-propagating beams through the earth'"'"'s atmosphere. The lasers are tuned such that the sum of the energies of the photons in each of the laser beams equals that associated with a predetermined transition of a gas in the earth'"'"'s atmosphere. In one embodiment, a pulsed laser and a CW laser are used. The pulse from the pulsed laser propagates along the CW beam produced by the CW laser and overlaps the CW beam at positions determined by a range gating technique, which makes possible the measurement of the two photon absorption at the various positions of overlap or coincidence. In one embodiment, the subject apparatus is utilized for pollution monitoring, in which the frequencies of the lasers are tuned such that the energies of the photons from these lasers add up to a transition of a predetermined pollutant.
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Citations
30 Claims
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1. Apparatus for making remote atomic absorption measurements comprising:
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means, including two collimated counter-propagating beams of coherent energy, for establishing two-photon absorption in the earth'"'"'s atmosphere at a number of selectable locations along the direction of said beams, and, means for measuring a two-photon absorption related characteristic of one of said beams after said one beam has participated in establishing two-photon absorption at a selected location. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18)
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19. Apparatus for making remote atomic absorption measurement comprising:
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means, including two collimated counter-propagating beams of coherent energy, for establishing two-photon absorption in the earth'"'"'s atmosphere at selected locations, means for producing stimulated emission at the locations of two-photon absorption, and, means for measuring said stimulated emission at said selected locations. - View Dependent Claims (20, 21)
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22. Apparatus for measuring atomic absorption associated with atoms or molecules of a gas comprising:
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means, including two collimated counter-propagating beams of coherent energy, for establishing two-photon absorption in said gas, and, means for measuring a two-photon absorption related characteristic of one of said beams after said one beam has participated in establishing two-photon absorption. - View Dependent Claims (23, 24, 25, 26, 27)
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28. Apparatus for measuring atomic absorption associated with atoms or molecules of a gas comprising:
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means, including two collimated counter-propagating beams of coherent energy, one of said beams being linearly polarized, for establishing absorption in said gas, and, means including crossed polarizer detection means for measuring an absorption related characteristic of said linearly polarized beam after said linearly polarized beam has participated in establishing said absorption.
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29. Apparatus for measuring atomic absorption associated with atoms or molecules of an unconfined gas in the earth'"'"'s atmosphere comprising:
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means, including two counter-propagating beams of coherent energy for establishing absorption in said unconfined gas, and, means for measuring an absorption related characteristic of one of said beams after said one beam has participated in establishing said absorption. - View Dependent Claims (30)
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Specification