Laser flashlight

• US 6,142,650 A
• Filed: 07/07/1998
• Issued: 11/07/2000
• Est. Priority Date: 07/10/1997
• Status: Expired due to Term

• Current Assignee: LE Sys Incorporated
• Original Assignee: LE Sys Incorporated
• Inventors: Brown, David C., Nelson, Richard J., Casazza, Titus A., Kohoe, Jay
• Primary Examiner(s): Spyrou, Cassandra
• Assistant Examiner(s): Treas, Jared
• Application Number:
  US09/111,335
• Time in Patent Office: 854 Days
• Field of Search: 362/259, 362/109, 362/116, 362/118, 353/42, 353/43, 372/22
• US Class Current: 362/259
• CPC Class Codes: F41H 13/0056 for blinding or dazzling, i.e. by overstimulating the opponent's eyes or the enemy's sensor equipment
• CPC Class Codes: H01S 3/005 Optical devices external to the laser cavity, specially adapted for lasers, e.g. for homogenisation of the beam or for manipulating laser pulses, e.g. pulse shaping shaping laser beam for working metal or other materials B23K26/06; optical elements, systems or apparatus in general G02B
• CPC Class Codes: H01S 3/025 of solid state lasers, e.g. housings or mountings
• CPC Class Codes: H01S 3/0405 Conductive cooling, e.g. by heat sinks or thermo-electric elements
• CPC Class Codes: H01S 3/09415 the pumping beam being parallel to the lasing mode of the pumped medium, e.g. end-pumping
• CPC Class Codes: H01S 3/109 Frequency multiplication, e.g. harmonic generation
• CPC Class Codes: H01S 5/02251 using optical fibres
• CPC Class Codes: H01S 5/02325 Mechanically integrated components on mount members or optical micro-benches

Abstract

A laser flashlight employs a laser emitter disposed within a housing for emitting a coherent light along an optical axis toward the light emitting end of the housing. A power supply selectively applies electricity from a battery pack disposed within the housing to the laser emitter. An optical system disposed within the housing intermediate the laser emitter and the light emitting end of the housing includes a laser element pumped by the laser emitter, a frequency/wavelength converter, and a resonator, to form the coherent light into a laser beam. A beam expander receives the laser beam, disperses the laser beam, and transmits the dispersed laser beam from the light emitting end of the housing into the ambient environment. The dispersion of the laser beam is such that the laser beam is safe for the human eye at the light emitting end of the housing.

Claims

1. A hand-held laser flashlight for emitting an eyesafe light dispersion pattern into an ambient environment comprising:

a housing having first and second ends;

a first laser emitter disposed within the housing for emitting a first coherent light beam toward the first end of the housing along an optical axis;

a power controller powered by at least one battery for selectively applying an electrical input to the first laser emitter;

an optical system disposed within the housing along the optical axis intermediate the first laser emitter and the first end of the housing and responsive to the coherent light beam for generating a laser beam for projection along the optical axis, the optical system including a resonator having an optical element comprising an optically transmissive material for propagating laser energy along the optical axis and a converter, the optical element receiving the first coherent light beam emitted by the diode and emitting a first laser beam having a first wavelength, the converter receiving the first laser beam from the optical element, converting the first wavelength to a second wavelength, respectively, and emitting a second laser beam having the second wavelength toward the first end of the housing, the optical element having a substantially flat end surface facing the first laser emitter, the converter having a convex end surface facing the first end of the housing, the end surface of the optical element and the convex end surface of the converter defining the resonator; and

a light transmissive beam expander disposed at the first end of the housing along the optical axis, the beam expander having oppositely disposed input and output optical surfaces, the laser beam impinging the input surface at a first beam diameter and exiting the exit surface at a second beam diameter, the laser beam exiting the exit surface having an intensity which may not be greater than 26 mW/cm².

2. The laser flashlight of claim 1 wherein the first laser emitter includes a diode and the optical system includes an optical element comprising an optically transmissive material for propagating laser energy along the optical axis and a converter, the optical element receiving the first coherent light beam emitted by the diode and emitting a first laser beam having a first wavelength, the converter receiving the first laser beam from the optical element, converting the first wavelength to a second wavelength, respectively, and emitting a second laser beam having the second wavelength to the beam expander.

3. The laser flashlight of claim 2 wherein the converter includes a resonator comprising a harmonic generating crystal, the resonator shifting the first wavelength of the first laser beam to an intermediate wave length and the harmonic generating crystal shifting the intermediate wave length to the second wavelength of the second laser beam.

4. The laser flashlight of claim 3 wherein the harmonic generating crystal is a second harmonic generating crystal, the first wavelength is substantially equal to 808 nm, the intermediate wave length is substantially equal to 1064 nm, and the second wavelength is substantially equal to 532 nm.

5. The laser flashlight of claim 3 wherein the harmonic generating crystal is a second harmonic generating crystal, the first wavelength is substantially equal to 808 nm, the intermediate wave length is substantially equal to 945 nm, and the second wavelength is substantially equal to 473 nm.

6. The laser flashlight of claim 3 wherein the optical system further includes an optically transmissive heat conductive element having a thermal conductivity greater than or equal to that of the optical element and a heat sink, the heat sink being in thermal contact with the optical element via the heat conductive element.

7. The laser flashlight of claim 6 wherein the heat conductive element has opposed first and second axially spaced end surfaces, the second end surface of the heat conductive element being adjacent to the optical element, the first and second end surfaces being coated with a material that is anti-reflective at the first wavelength.

8. The laser flashlight of claim 7 wherein the optical element has opposed first and second axially spaced end surfaces, the first end surface of the optical element being adjacent to the second surface of the heat conductive element, the first end surface of the optical element being coated with a material that is highly transmissive at the first wavelength and highly-reflective at the intermediate and second wavelengths.

9. The laser flashlight of claim 3 wherein the optical system further includes an outcoupler disposed intermediate the converter and the beam expander, the outcoupler having opposed first and second axially spaced end surfaces, the first end surface of the outcoupler being disposed adjacent the converter and having a concave shape.

10. The laser flashlight of claim 9 wherein the first end surface of the outcoupler is coated with a material which is highly-reflective at the intermediate wavelength and highly-transmissive at the second wavelength.

11. The laser flashlight of claim 9 wherein the first end surface of the outcoupler is coated with a material which is partially-reflective at the intermediate wavelength.

12. The laser flashlight of claim 3 wherein the optical system further comprises an optically transmissive harmonic mirror element axially disposed intermediate the optical element and the harmonic generating crystal, the harmonic mirror having opposed first and second axially spaced end surfaces, the second end surface of the harmonic mirror facing the harmonic generating crystal and being coated with a material that is highly-transmissive at the intermediate wavelength and highly-reflective at the second wavelength.

13. The laser flashlight of claim 3 wherein the harmonic generating crystal has an end surface facing the optical element, the end surface of the harmonic generating crystal being coated with material which is highly-transmissive at the intermediate wavelength and highly-reflective at the second wavelength.

14. The laser flashlight of claim 3 wherein the harmonic generating crystal has a substantially flat first end surface and a convex-shaped second end surface, the first end surface facing the optical element.

15. The laser flashlight of claim 2 wherein the optical system further includes at least one lens disposed intermediate the first laser emitter and the optical element.

16. The laser flashlight of claim 2 wherein the beam expander comprises at least one collimating lens disposed on the optical axis and the optical system further includes a gradient index or ashperic lens disposed on the optical axis intermediate the converter and the collimating lens.

17. The laser flashlight of claim 1 wherein the first laser emitter comprises a diode and an optical fiber having a first end for receiving the first coherent light beam emitted by the diode and a second end for transmitting the first coherent light beam to the optical system.

18. The laser flashlight of claim 1 wherein the first laser emitter comprises a diode and a collimating lens for receiving, collimating and transmitting the first coherent light beam emitted by the diode to the optical system.

19. The laser flashlight of claim 18 wherein the optical system comprises an optical fiber disposed coaxially with the optical axis, the optical fiber having a first end for receiving the first coherent light beam emitted by the collimating lens and a second end for transmitting the laser beam to the beam expander.

20. The laser flashlight of claim 19 wherein the optical system further comprises a gradient index or aspheric lens disposed on the optical axis intermediate the second end of the optical fiber and the beam expander.

21. The laser flashlight of claim 1 further comprising means for pulsing the second laser beam.

22. The laser flashlight of claim 21 wherein the means for pulsing the second laser beam selectively interrupts the second laser beam to produce intermittent asymmetric laser beam pulses.

23. A laser flashlight for emitting a light dispersion pattern into an ambient environment comprising:

a housing having a light emitting end;

a laser emitter disposed within the housing, the laser emitter emitting a coherent light toward the light emitting end of the housing along an optical axis upon the application of electricity;

a power supply for selectively applying electricity to the laser emitter;

an optical system disposed within the housing, along the optical axis, intermediate the laser emitter and the light emitting end of the housing, the optical system including a laser element pumped by the laser emitter, a converter, and a resonator, the laser element receiving the coherent light emitted by the laser emitter and emitting a first laser beam having a first wavelength, the resonator shifting the first laser beam to an intermediate laser beam having an intermediate wave length, the converter receiving the intermediate laser beam and converting the intermediate laser beam to a second laser beam having a second wavelength and emitting the second laser beam along the optical axis, the optical system further comprising an optically transmissive mirror element axially disposed intermediate the laser element and the converter, the mirror element being highly-transmissive at the intermediate wavelength and highly-reflective at the second wavelength; and

a light transmissive beam expander disposed at the light emitting end of the housing and along the optical axis, the beam expander receiving and dispersing the second laser beam, wherein the second laser beam has an intensity not greater than 26 mW/cm².

24. The laser flashlight of claim 23 wherein the converter comprises a second harmonic generating crystal, the first wavelength is substantially equal to 808 nm, the intermediate wave length is substantially equal to 1064 nm, and the second wavelength is substantially equal to 532 nm.

25. The laser flashlight of claim 23 wherein the optical system further includes an optically transmissive heat conductive element having a thermal conductivity greater than or equal to that of the laser element and a heat sink, the heat sink being in thermal contact with the laser element via the heat conductive element.

26. A hand-held laser flashlight for emitting an eyesafe light dispersion pattern into an ambient environment comprising:

a housing having first and second ends;

a first laser emitter disposed within the housing for emitting a first coherent light beam toward the first end of the housing along an optical axis;

a second laser emitter emitting a second coherent light beam along a light path;

a power controller powered by at least one battery for selectively applying an electrical input to the first and second laser emitter;

an optical system including a polarizer disposed within the housing in the light path and along the optical axis intermediate the first laser emitter and the first end of the housing and responsive to the first and second coherent light beams for generating a laser beam for projection along the optical axis; and

a light transmissive beam expander disposed at the first end of the housing along the optical axis, the beam expander having oppositely disposed input and output optical surfaces, the laser beam impinging the input surface at a first beam diameter and exiting the exit surface at a second beam diameter, the laser beam exiting the exit surface having an intensity which may not be greater than 26 mW/cm².

27. The laser flashlight of claim 26 wherein the optical system further comprises first and second beam forming optics disposed intermediate the first and second laser emitters and the polarizer.

28. The laser flashlight of claim 26 wherein the optical system further comprises a beam expander lens disposed on the optical axis intermediate the polarizer and the beam expander.

29. The laser flashlight of claim 26 wherein the first and second coherent light beams each have a wavelength, the wavelength of the second coherent light beam being different from the wavelength of the first coherent light beam.

30. The laser flashlight of claim 29 wherein the first laser emitter comprises a diode-pumped, frequency doubled Nd:

YVO₄ laser and the second laser emitter comprises a red diode laser.

31. The laser flashlight of claim 26 wherein the laser beam transmitted by the polarizer is composed of a portion of the first coherent light beam having an s-polarization and a portion of the second coherent light beam having a p-polarization.

32. The laser flashlight of claim 26 wherein the laser beam transmitted by the polarizer is composed of a portion of the first coherent light beam having a p-polarization and a portion of the second coherent light beam having an s-polarization.

33. The laser flashlight of claim 26 wherein the first laser emitter is a diode laser, the optical system comprises an optical fiber disposed on the optical axis having a first end for receiving the first coherent light beam emitted by the first laser emitter and a second end for transmitting the laser beam to the beam expander.