LASER DETECTION SYSTEM AND METHOD

• US 20130293882A1
• Filed: 06/21/2012
• Published: 11/07/2013
• Est. Priority Date: 06/21/2011
• Status: Active Grant

• Current Assignee: Alakai Defense Systems, Inc.
• Original Assignee: Alakai Defense Systems, Inc.
• Inventors: Dottery, Ed, Vilardi, Frank, Pohl, Kennth, Vunck, Darius, Waterbury, Robert
• Granted Patent: US 9,157,801 B2
• Time in Patent Office: Days
• US Class Current: 356/301
• CPC Class Codes: G01J 3/0235 using means for replacing an element by another, for replacing a filter or a grating
• CPC Class Codes: G01J 3/0289 Field-of-view determination; Aiming or pointing of a spectrometer; Adjusting alignment; Encoding angular position; Size of measurement area; Position tracking
• CPC Class Codes: G01J 3/44 Raman spectrometry; Scattering spectrometry ; Fluorescence spectrometry
• CPC Class Codes: G01N 2021/1793 Remote sensing
• CPC Class Codes: G01N 21/65 Raman scattering

Abstract

A system comprises a processing system, a laser system, a telescope system, a detector system and optical systems operatively arranged such that the laser system may be capable of outputting multiple wavelengths to a common telescope system, and the detector system is capable of receiving signatures from the same telescope system, under the control of a control system. The processor system processes signals received from the detector system to determine substances identified by known signatures. For example, a plurality of detectors in the detector system each receive a range of wavelengths of the signatures received by the telescope system. For example, a variable beam diverger and variable beam expander operatively control expansion and divergence of the output the laser system. For example, a beam reducer and lenslet array may operatively transmit signatures via optical fiber bundle to one or more of the detectors.

Claims

1. A laser detection system for use in stand-off detection of electromagnetic signatures of substances on a surface of a target, the system comprising:

a laser system comprising optical elements and a single wavelength source beam for producing an output beam;

a telescope system arranged with the laser system such that the output beam is directed through the telescope system via an optical component, the optical component comprising a reflective surface for reflecting the output beam, the signatures or both the output beam and the signatures, such that the output beam is directed onto the surface of the target through the telescope system and the electromagnetic signatures of substances on the surface of the target are captured through the same telescope system and are directed by the telescope system to the optical component;

a detector system comprising an optical system, at least one spectrometer operatively coupled to the optical system, and a processing unit electrically coupled with the at least one spectrometer such that electrical signals from the at least one spectrometer are analyzed by the processing unit, the optical system of the detector system being optically coupled to the telescope system via the optical component of the laser system; and

a control unit electronically coupling and controlling the laser system, the telescope system and the detector system, such that signatures are capable of being detected at a stand-off distance of at least 40 meters or greater.

2. The system of claim 1, wherein the laser system further comprises a variable beam expander and a variable beam diverger, operatively arranged such that at least a portion of the output beam passes through the variable beam expander and the variable beam diverger prior to being directed to the telescope system.

3. The system of claim 2, further comprising a rangefinder electrically coupled with the control unit, wherein the variable beam expander and the variable beam diverger include movable components capable of focusing the at least a portion of the output beam on the surface of the target under control of the control unit based on signals received by the control unit from the rangefinder, and the control unit controls the movement of the movable components of the variable beam expander and the variable beam diverger in combination with movement of a secondary mirror of the telescope system in relation to a primary mirror of the telescope system.

4. The system of claim 2, wherein the variable beam expander and the variable beam diverger result are controlled by the control unit such that the output beam exits the telescope system such that the output beam is eye safe.

5. The system of claim 4, wherein the output beam is collimated.

6. The system of claim 2, wherein the optical system of the detector system comprises:

a beam reducer;

a lenslet array; and

an optical fiber bundle having a plurality of optical fibers operatively arranged such that at least a portion of the signatures are directed through the beam reducer, are directed through the lenslet array and are directed into a plurality of the plurality of optical fibers, such that signatures are directed by the plurality of the plurality of optical fibers to the at least one spectrometer.

7. The system of claim 6, wherein the plurality of optical fibers are operatively arranged such that the signatures are directed onto a central portion of the optical fiber bundle and are output from a linear array of the plurality of optical fibers.

8. The system of claim 7, wherein the linear array of the plurality of optical fibers are directed through a linear aperture slit of the at least one spectrometer.

9. The system of claim 8, wherein the lenslet array comprises a 10×

10 square lenslet array, defining a outer square of the lenslet array.

10. The system of claim 9, wherein the optical fiber bundle comprises 81 fibers disposed in an array of fibers contained within a circle circumscribed within the outer square of the lenslet array.

11. The system of claim 3, wherein the power and wavelength of the output beam is eye safe as emitted by the laser detection system, and the control unit selects a focal length of the output beam of the laser system, a focal length of the telescope system and a time delay for triggering activation of the at least one spectrometer of the detector system such that electromagnetic signatures of substances on the surface of the target are capable of being detected at stand off distances up to fifty meters or greater from the telescope system.

12. The system of claim 11, wherein the control unit selects a focal length of the output beam of the laser system, a focal length of the telescope system and a time delay for triggering activation of the at least one spectrometer of the detector system such that electromagnetic signatures of substances on the surface of the target are capable of being detected at stand off distances up to one hundred meters or greater from the telescope system.

13. The system of claim 1, wherein the control unit selects a focal length of the output beam of the laser system, a focal length of the telescope system and a time delay for triggering activation of the at least one spectrometer of the detector system such that electromagnetic signatures of substances on the surface of the target are capable of being detected at stand off distances up to three hundred meters or greater from the telescope system.

14. The system of claim 1, wherein the optical elements of the laser system are arranged to produce an output beam selectively comprising more than one wavelength from the single wavelength source, each of at least two different wavelengths being capable of stimulating Raman signatures from substances on the surface of the target, each of the at least two different wavelengths of the output beam being directed to the telescope system via the same optical component coupling the telescope system with the laser system, wherein the optical component comprises coatings capable of reflecting the at least two different wavelengths of the output beam.

15. The system of claim 3, wherein the rangefinder is boresighted with an optical axis of the telescope system.

16. The system of claim 3, further comprising a targeting system comprising a targeting mirror, wherein the targeting system is coupled electronically with the control unit and is coupled with the telescope system such that the output beam emitted from the telescope system is directed to the targeting system and any signatures incident on the targeting mirror of the targeting system is directed to a primary mirror of the telescope system, wherein the targeting mirror of the targeting system is capable of redirecting the output beam onto the surface of the target without moving any of the laser system, the detector system or the telescope system.

17. The system of claim 16, wherein targeting system is capable of redirecting the output beam azimuth and elevation without moving any of the laser system, the detector system or the telescope system.

18. The system of claim 17, wherein the rangefinder is boresighted with the targeting system.

19. The system of claim 17, wherein the targeting system includes a user interface for selecting targets using the targeting system.

20. The system of claim 17, wherein the targeting system automatically selects targets under control of the control unit.

21. The system of claim 20, wherein the targeting system automatically tracks selected targets under control of the control unit.

22. The system of claim 1, further comprising a stabilization and isolation system, wherein the stabilization and isolation system couples the laser detection system to a vehicle.

23. The system of claim 17, further comprising a stabilization and isolation system, wherein the stabilization and isolation system couples the laser detection system to a vehicle, wherein the stabilization and isolation system does not interfere with the targeting system.

24. The system of claim 17, wherein the control unit controls the targeting system, determines a range to a selected target using the rangefinder, moves the movable components of the variable beam expander and the variable beam diverger, moves the secondary mirror of the telescope system in relation to a primary mirror of the telescope system, and operatively activates the at least one spectrometer at a predefined time such that the laser detection system is capable of stand-off distances up to one hundred meters using only a single wavelength source beam.

25. The system of claim 1, wherein the at least one spectrometer of the detector system is a plurality of spectrometers and the optical system of the detector system comprises at least one dichroic or multi-chroic filter that redirects one range of wavelengths of the signatures received by the detector system to a first one of the plurality of spectrometers and a second range of wavelengths of the signatures received by the detector system to a second one of the plurality of spectrometers.