LCWG steered laser transmitter and situational awareness sensor with wavelength conversion

• US 9,904,081 B2
• Filed: 06/20/2016
• Issued: 02/27/2018
• Est. Priority Date: 06/20/2016
• Status: Active Grant

• Current Assignee: Raytheon Company (Rtx Corporation)
• Original Assignee: Raytheon Company (Rtx Corporation)
• Inventors: Uyeno, Gerald P., Keller, Sean D.
• Primary Examiner(s): LUU, THANH X
• Application Number:
  US15/187,221
• Publication Number:
  US 20170363887A1
• Time in Patent Office: 617 Days
• CPC Class Codes: G01S 17/04 Systems determining the presence of a target
• CPC Class Codes: G01S 17/42 Simultaneous measurement of distance and other co-ordinates indirect measurement G01S17/46
• CPC Class Codes: G01S 17/89 for mapping or imaging
• CPC Class Codes: G01S 7/4814 of transmitters alone
• CPC Class Codes: G01S 7/4817 relating to scanning
• CPC Class Codes: G02B 5/001 Axicons, waxicons, reflaxicons
• CPC Class Codes: G02B 5/08 Mirrors vehicle mirrors involving special optical features B60R1/08
• CPC Class Codes: G02F 1/1313 specially adapted for a particular application
• CPC Class Codes: G02F 1/1326 Liquid crystal optical waveguides or liquid crystal cells specially adapted for gating or modulating between optical waveguides
• CPC Class Codes: G02F 1/292 by controlled diffraction or phased-array beam steering controlled diffraction for optical switching G02F1/31
• CPC Class Codes: G02F 1/3501 Constructional details or arrangements of non-linear optical devices, e.g. shape of non-linear crystals
• CPC Class Codes: G02F 1/3503 Structural association of optical elements, e.g. lenses, with the non-linear optical device
• CPC Class Codes: G02F 1/3507 Arrangements comprising two or more nonlinear optical devices
• CPC Class Codes: G02F 1/3509 Shape, e.g. shape of end face
• CPC Class Codes: G02F 1/3532 Arrangements of plural nonlinear devices for generating multi-colour light beams, e.g. arrangements of SHG, SFG, OPO devices for generating RGB light beams
• CPC Class Codes: G02F 1/37 for second-harmonic generation G02F1/3532 takes precedence
• CPC Class Codes: H01S 3/0071 Beam steering, e.g. whereby a mirror outside the cavity is present to change the beam direction
• CPC Class Codes: H01S 3/0092 Nonlinear frequency conversion, e.g. second harmonic generation [SHG] or sum- or difference-frequency generation outside the laser cavity nonlinear frequency conversion per se G02F1/35
• CPC Class Codes: H01S 3/2308 Amplifier arrangements, e.g. MOPA

Abstract

A steerable laser transmitter and situational awareness sensor uses a liquid crystal waveguide (LCWG) to steer a spot-beam onto a conical mirror, which in turn redirects the spot-beam to scan a FOV. The spot-beam passes through one or more annular sections of non-linearly material (NLM) formed along the axis and around the conical mirror. Each NLM section converts the wavelength of the spot-beam to a different wavelength while preserving the steering of the spot-beam. The LCWG may shape or move the spot-beam along the axis of the conic mirror to sequentially, time or time and spatially multiplex the spot-beam between the original and different wavelengths. This provides multispectral capability from a single laser source. The transmitter also supports steering the spot-beam at a wavelength at which the LCWG cannot steer directly.

Claims

1. A laser device, comprising:

a laser configured to generate a collimated spot-beam at an input wavelength along an optical axis;

a liquid crystal waveguide (LCWG) along the optical axis responsive to command signals to steer the collimated spot-beam at the input wavelength in two-dimensions about the optical axis;

a controller configured to issue command signals to the LCWG to steer the collimated spot-beam;

a fixed mirror including a first conic section oriented along the optical axis that redirects the collimated spot-beam to scan a two-dimensional field-of-view (FOV); and

a first annular cylindrical shaped optical element with a first optical non-linear material oriented along an axis coincident with the optical axis, said redirected collimated spot-beam passing through the first optical non-linear material to convert the input wavelength to a different first output wavelength while preserving the steering of the collimated spot-beam over the FOV.

2. The laser device of claim 1, further comprising:

a detector configured to sense a reflected component of the collimated spot-beam at the output wavelength.

3. The laser device of claim 1, wherein the LCWG is configured to steer the collimated spot-beam in a range about the input wavelength, wherein the different first output wavelength lies outside said range.

4. The laser device of claim 1, wherein the fixed mirror includes a second conic section different than said first conic section, said second conic section configured to redirect the collimated spot-beam parallel to the redirected collimated spot-beam from the first conic section whereby the collimated spot-beam is transmitted at a second output wavelength different than said first output wavelength, said controller configured to issue command signals to the LCWG to steer the collimated spot-beam to said first and second different conic sections to scan a multispectral spot-beam over the two-dimensional FOV.

5. The laser device of claim 4, wherein the collimated spot-beam redirected from the second conic section is transmitted at the input wavelength as the second output wavelength over the FOV.

6. The laser device of claim 4, further comprising:

a second annular cylindrical shaped optical element with a second optical non-linear material oriented along the axis coincident with the optical axis, said collimated spot-beam redirected from the second conic section passing through the second optical non-linear material to convert the optical wavelength to the different second output wavelength while preserving the steering of the collimated spot-beam over the FOV.

7. The laser device of claim 4, wherein the controller is configured to issue command signals to steer the collimated spot-beam sequentially around the first conic section to scan the two-dimensional FOV at the first output wavelength and around the second conic section to scan the two-dimensional FOV at the second output wavelength to sequentially multiplex the first and second output wavelengths.

8. The laser device of claim 4, wherein the controller is configured to issue command signals to steer the collimated spot-beam back-and-forth between the first and second conic sections to time multiplex the first and second output wavelengths to scan the two-dimensional FOV.

9. The laser device of claim 8, wherein the controller is configured to issue command signals to increment the position of the scan in the FOV to time and sequentially multiplex the first and second output wavelengths to scan the two-dimensional FOV.

10. The laser device of claim 4, further comprising:

an L0 optic positioned between the LCWG and the fixed mirror to shape the spot-beam to have an oblong shape whose major axis is oriented along optical axis so that the collimated spot-beam covers both the first and second conic sections to simultaneously generate the multispectral output.

11. The laser device of claim 4, further comprising:

a ring amplifier comprising one or more pumps configured to pump a gain medium in the form of a ring around said optical axis, said ring amplifier configured such that the collimated spot-beam at the input wavelength as redirected from said first or said second conic section passes through the gain medium one or more times to amplify the collimated spot-beam while preserving the steering of the spot-beam over the FOV.

12. The laser device of claim 1, wherein said optical axis is oriented in the Z direction,

said LCWG is configured to steer the collimated spot-beam about the optical axis to a location Theta X and Theta Y from the optical axis where Theta X is the angle between the projection of the instantaneous location of the axis of spot-beam on the X-Y plane and the Z axis and Theta Y is the angle between the instantaneous location of the axis of the spot-beam and the Z axis such that Theta X is in the plane of the X axis and Theta Y is in the plane of the Y axis, Theta Z is the angle between the projection of the instantaneous location of the axis of the steered collimated spot-beam and the Z axis;

said controller is configured to issue command signals to the LCWG to steer the collimated spot-beam to the desired Theta X and Theta Y; and

said fixed mirror'"'"'s conic section is configured to redirect the collimated spot-beam to a location Phi and Theta Z′

where Phi is the angle between the projection of the instantaneous location of the axis of the redirected spot-beam on the X-Y plane and the X axis and Theta Z′

is the angle between the projection of the instantaneous location of the axis of redirected spot-beam on the Z axis and Theta Z′

is greater than Theta Z, wherein the redirected collimated spot-beam scans a field-of-view (FOV) defined by the values of Phi and Theta Z′

.

13. The laser device of claim 1, further comprising:

an optic L1 configured to focus the collimated spot-beam onto the conical section of the fixed mirror;

a structural member configured to provide support primarily in the direction parallel to the sensor axis, said structural support having N discrete apertures formed therein at 360/N degree intervals; and

N transport optic channels placed around the fixed mirror at 360/N degree intervals, each channel comprising a cylindrical optic L2 configured to collimate the redirected spot-beam and a cylindrical optic L3 configured to direct the redirected collimated spot-beam through the corresponding aperture.

14. The laser device of claim 1, wherein the LCWG is not configurable to steer the collimated spot-beam at the first output wavelength.

15. A laser device, comprising:

a laser configured to generate a collimated spot-beam at an input wavelength along an optical axis;

a liquid crystal waveguide (LCWG) along the optical axis responsive to command signals to steer the collimated spot-beam at the input wavelength in two-dimensions about the optical axis;

a fixed mirror including first and second different conic section oriented along the optical axis that redirect the collimated spot-beam to scan a two-dimensional field-of-view (FOV);

a first annular cylindrical shaped optical element with a first optical non-linear material oriented along an axis coincident with the optical axis, said optical element configured such that the collimated spot-beam redirected from said first conic section passes through the first optical non-linear material to convert the input wavelength to a different first output wavelength while preserving the steering of the collimated spot-beam over the FOV; and

a controller configured to issue command signals to the LCWG to steer the collimated spot-beam to said first and second different conic sections to scan a multispectral spot-beam at the first output wavelength and a second output wavelength over the two-dimensional FOV.

16. The laser device of claim 15, wherein the spot-beam redirected from the second conic section is transmitted at the input wavelength as the second output wavelength over the FOV.

17. The laser device of claim 15, further comprising:

a second annular cylindrical shaped optical element with a second optical non-linear material oriented along the axis coincident with the optical axis, said second optical element configured such that the collimated spot-beam redirected from said second conic section passes through the second optical non-linear material to convert the input wavelength to the second output wavelength while preserving the steering of the collimated spot-beam over the FOV.

18. The laser device of claim 15, wherein the controller is configured to issue command signals to steer the collimated spot-beam sequentially around the first conic section to scan the two-dimensional FOV at the first output wavelength and around the second conic section to scan the two-dimensional FOV at the second output wavelength.

19. The laser device of claim 15, wherein the controller is configured to issue command signals to steer the collimated spot-beam back-and-forth between the first and second conic sections to time multiplex the first and second output wavelengths to scan the two-dimensional FOV.

20. The laser device of claim 19, wherein the controller is configured to issue command signals to increment the position of the scan in the FOV to time and sequentially multiplex the first and second output wavelengths to scan the two-dimensional FOV.

21. The laser device of claim 15, further comprising:

an L0 optic positioned between the LCWG and the fixed mirror to shape the collimated spot-beam to have an oblong shape whose major axis is oriented along optical axis so that the collimated spot-beam covers both the first and second conic sections to simultaneously generate the multispectral output.