REMOTE SENSING APPARATUS AND METHODS

• US 3,768,908 A
• Filed: 01/04/1971
• Issued: 10/30/1973
• Est. Priority Date: 01/04/1971
• Status: Expired due to Term

• Current Assignee: Solomon Zaromb
• Original Assignee: Solomon Zaromb
• Inventors: Zaromb, Solomon
• Primary Examiner(s): Wibert, Ronald L.
• Assistant Examiner(s): Clark, Conrad
• Application Number:
  US05/103,507
• Time in Patent Office: 1,030 Days
• Field of Search: 356/103,207,256,75 250/71,218,104
• US Class Current: 356/338
• CPC Class Codes: G01J 3/44 Raman spectrometry; Scattering spectrometry ; Fluorescence spectrometry
• CPC Class Codes: G01N 2021/1793 Remote sensing
• CPC Class Codes: G01N 21/39 using tunable lasers
• CPC Class Codes: G01N 33/0027 concerning the detector

Abstract

A lidar spectroscopic apparatus comprises a laser transmitter and a receiver in which the radiation return is spectranalyzed, a fluorescent target at a considerable distance from said transmitter and receiver, and means for aiming said transmitter and receiver at said fluorescent target. The presence of pollutants between the lidar system and said target is deduced from the attenuation of the radiation return at several wavelengths and/or from the Raman backscatter due to specific air pollutants.

Claims

1. Remote sensing apparatus comprising a laser transmitter and a receiver, said receiver comprising an optical system for focusing radiation incident thereon onto a spectro-analyser, said spectroanalyser comprising means for measuring the radiation received at several selected wavelengths, said transmitter and receiver being located near each other and so directed that the laser beam from said transmitter approximately coincides with the volume viewed by said receiver, a fluorescent target at a considerable distance from said transmitter and receiver, said target having quantitatively established fluorescence characteristics, and means for aiming the radiation emitted from said transmitter at said fluorescent target.

2. Apparatus as claimed in claim 1 wherein said transmitter transmits radiation in the 0.25- 0.3 micron wavelength range.

3. Apparatus as claimed in claim 2, comprising a neodymium type laser with second and fourth harmonic generators yielding radiation of approximately 0.53 micron and 0.265 micron wavelength, respectively.

4. Apparatus as claimed in claim 1 wherein said target fluoresces in the 0.28- 0.4 micron range.

5. Apparatus as claimed in claim 1 wherein said target fluoresces in the 0.35- 0.5 micron range.

6. Apparatus as claimed in claim 1 wherein the fluorescent material in said target is supported by a sheet-like polymeric substrate.

7. Apparatus as claimed in claim 1 wherein the fluorescent material in said target is supported by metal foil.

8. Apparatus as claimed in claim 1 wherein said target is air-borne.

9. Apparatus as claimed in claim 1 comprising means for generating said target in the form of a cluster of numerous small air-borne fluorescent particles.

10. A method of detecting air pollutants at a distance which comprises:

transmitting laser radiation to a fluorescent target, measuring the intensity of the radiation returning from said target at several different wavelengths, and deducing the presence of said pollutants from the attenuation of the radiation which is emitted by said target.

11. A method as claimed in claim 10 wherein said fluorescent target is air-borne.

12. A method as claimed in claim 11 wherein said target is lifted by a ballon and held down by strings which are manipulated to maintain said target in the desired position.

13. A method as claimed in claim 11 comprising generating a cluster of air-borne fluorescent particles at a large distance from said lidar system.

14. A method of remotely detecting sulfur dioxide and ozone which comprises:

transmitting laser radiation of at least two distinct wavelengths from a lidar system, at least one of said wavelengths being in the wavelength range of 0.25 to 0.3 micron, measuring the intensity of the radiation returning to said lidar system at several wavelengths which are different than the transmitted wavelengths, some of said different wavelengths arising from the Raman-scattering of the transmitted radiation by at least one major atmospheric constituent, especially nitrogen, and comparing the attenuation of said returning radiation at said different wavelengths.

15. A method as claimed in claim 14 wherein the presence of pollutants is also deduced from an enhancement of said returning radiation at wavelengths corresponding to the Raman-shifted backscatter due to carbon dioxide and water.

16. A method as claimed in claim 15 comprising tracking a pollutant plume to its source by measuring the density of the pollutants along different directions and following along the direction of highest pollutant density.