Dual mode laser target designator/rangefinder with an optical parametric oscillator-optical parametric amplifier (OPO-OPA) converter

Patent metadata

Field	Value
Publication number	US-10852432-B2
Application number	US-201615352029-A
Country	US
Kind code	B2
Filing date	Nov 15, 2016
Priority date	Nov 15, 2016
Publication date	Dec 1, 2020
Grant date	Dec 1, 2020

Abstract

The current disclosure is directed to an apparatus and method of a Laser Designator/Rangefinder (LDR) having two wavelengths of 1064 nm and 1572 nm. The 1064 nm wavelength laser is generated by a pump diode by exciting Nd:YAG medium (source). The 1572 nm wavelength laser is produced using an OPO-OPA converted which is located in a by-pass path. Because the 1572 nm wavelength uses near diffraction limited signal, it provides long range identification and tracking capability needed for advanced tactical platforms, while using the smallest transmit aperture, in a low Size, Weight and Power Consumption (SWaP) package.

First claim

What is claimed:

1. A long range laser target designator/rangefinder (LDR) system, comprising:
a 1064 nm wavelength laser, wherein a medium of the laser is adapted to be excited by a laser pumping source;
an optical beam selector, wherein the optical beam selector is selectable between a range finding mode and a target designation mode;
an optical parametric oscillator-optical parametric amplifier (OPO-OPA) converter system wherein the converter system comprises an OPO-OPA converter, a half wave plate and a beam reducer, wherein the 1064 nm wavelength laser passes through the OPO-OPA converter system if the range finding mode is selected and bypasses the OPO-OPA converter system if the target designation mode is selected;
a polarizer located between the half wave plate and an optical parametric oscillator (OPO) of the OPO-OPA converter system, wherein the polarizer splits the 1064 nm wavelength laser into a first split laser beam and a second split laser beam, wherein the first split laser beam has a low energy level of less than or equal to 20 mJ; and
a beam reducer located between the polarizer and the OPO, wherein the beam reducer is configured to reduce a diameter of the first split laser beam prior to entering a cavity defined by the OPO-OPA converter, wherein the diameter of the reduced first split laser beam is reduced to less than 1 mm.

2. The LDR system of claim 1 , further comprising a beam expander located between the laser pumping source and the half wave plate.

3. The LDR system of claim 1 , wherein the optical beam selector is a switch.

4. The LDR system of claim 1 , further comprising a first mirror located between the beam reducer and the OPO.

5. The LDR system of claim 1 , further comprising a beam expander located between an optical parametric oscillator (OPO) of the OPO-OPA converter and an optical parametric amplifier (OPA) of the OPO-OPA converter.

6. The LDR system of claim 5 , further comprising a second mirror located between the beam expander and the OPA.

7. The LDR system of claim 1 , wherein the OPO-OPA converter includes one or more crystals and wherein the crystals are comprised of Potassium Titanyl Phosphate (KTP), KTiOAsO 4 (KTA), RbTiOPO 4 (RTP), or RbTiOAsO 4 (RTA).

8. The LDR system of claim 1 , wherein the laser pumping source is selectively operated in a continuous pulse mode or burst pulse mode.

9. The LDR system of claim 8 , wherein the laser pumping source is operated in the continuous mode and is operated at a pulse repetition rate of from 8 Hz up to 20 Hz.

10. The LDR system of claim 8 , wherein the laser pumping source is operated in the burst pulse mode and is operated at a pulse repetition rate of from 0.2 kHz up to 1 kHz.

11. A method of determining a range of a target and designating the target comprising:
providing a long range laser target designator/rangefinder (LDR system) including an Optical Parametric Oscillator-Optical Parametric Amplifier converter (OPO-OPA converter) having a beam expander, a half wave plate and a polarizer;
pumping a laser source;
generating a 1064 nm wavelength laser beam;
selecting between a range finding mode and a target designation mode via an optical beam selector, wherein the target designation mode bypasses the OPO-OPA converter;
directing the 1064 nm wavelength laser beam through the beam expander, through the half wave plate and into the polarizer;
splitting the laser beam in the polarizer into a first split laser beam and a second split laser beam, wherein the first split laser beam has a low energy level of less than or equal to 20 mJ;
directing the first split laser beam into a beam reducer;
reducing a diameter of the first split laser beam in the beam reducer to less than 1 mm; and
directing the reduced diameter first split laser beam into an OPO of the OPO-OPA converter, wherein the OPO generates a diffraction limited beam from the reduced diameter first split laser beam and a cavity defined by the OPO-OPA converter.

12. The method of claim 11 , further comprising:
directing the first split laser beam through a beam reducer and into the cavity defined by the OPO-OPA converter;
circulating the first split laser beam in the cavity by reflecting the first split laser beam off a plurality of mirrors and through one or more crystals in an OPO of the OPO-OPA converter until the wavelength reaches approximately 1570 nm; and
directing the 1570 nm first split laser beam through an output coupler through a second beam expander and into an OPA of the OPO-OPA converter.

13. The method of claim 12 , further comprising:
utilizing the 1570 nm first split laser beam in the OPA as a seed source;
directing the second split laser beam from the polarizer into the OPA;
converting the wavelength of at least part of the second split laser beam to 1570 nm using the seed source.

14. The method of claim 13 , further comprising;
deflecting a remaining part of the second split laser beam exiting the OPA and
transmitting the 1570 nm wavelength lasers directly out of the OPA and
range finding the target using the 1570 nm wavelength lasers for range finding the target.

15. The method of claim 11 , further comprising:
electronically controlling the laser pumping source and
selecting to operate the laser pumping source in a continuous pulse mode or a burst pulse mode.

16. The method of claim 15 , wherein the laser pumping source is operated in the continuous pulse mode at a pulse repetition rate of from 8 Hz up to 20 Hz.

17. The method of claim 15 , wherein the laser pumping source is operated in the burst pulse mode at a pulse repetition rate of from 0.2 kHz up to 1 kHz.

18. The method of claim 11 , wherein the generated laser has energy; and the method further comprises:
passing the generated laser through a half wave plate.

19. The method of claim 11 , further comprising:
directing the first split laser beam through a beam reducer and into a cavity defined by the OPO-OPA converter;
circulating the first split laser beam in the cavity by reflecting the first split laser beam off a plurality of mirrors and through one or more crystals in an OPO of the OPO-OPA converter until the wavelength reaches 1570 nm; and
directing the 1570 nm first split laser beam through an output coupler through a second beam expander and into an OPA of the OPO-OPA converter.

Assignees

• Bae Sys Inf & Elect Sys Integ

Inventors

• Kelly David P
• Mccarthy John C
• Miller Christopher A
• Pretorius Hermanus S
• Snell Katherine J

Classifications

• G01S17/10 Primary

  using transmission of interrupted, pulse-modulated waves (determination of distance by phase measurements G01S17/32) · CPC title

• G02F1/39

  for parametric generation or amplification of light, infrared or ultraviolet waves · CPC title

• G01S7/4814

  of transmitters alone · CPC title

• H01S3/0092

  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 title

• F41G3/145

  using a target illuminator · CPC title