SCANNING LADAR WITH ADJUSTABLE OPERATIONAL PARAMETERS

• US 20080278715A1
• Filed: 05/11/2007
• Published: 11/13/2008
• Est. Priority Date: 05/11/2007
• Status: Active Grant

• Current Assignee: Rosemount Aerospace, Inc. (Rtx Corporation)
• Original Assignee: Rosemount Aerospace, Inc. (Rtx Corporation)
• Inventors: Ray, Mark D., Meneely, Clinton T., McIntosh, Malcolm B., Swenson, James W.
• Granted Patent: US 7,697,125 B2
• Time in Patent Office: Days
• US Class Current: 356/141.5
• CPC Class Codes: G01S 17/10 using transmission of interrupted, pulse-modulated waves determination of distance by phase measurements G01S17/32
• CPC Class Codes: G01S 17/42 Simultaneous measurement of distance and other co-ordinates indirect measurement G01S17/46
• CPC Class Codes: G01S 17/88 Lidar systems specially adapted for specific applications
• CPC Class Codes: G01S 17/89 for mapping or imaging
• CPC Class Codes: G01S 7/4812 transmitted and received beams following a coaxial path
• CPC Class Codes: G01S 7/4817 relating to scanning
• CPC Class Codes: G01S 7/483 Details of pulse systems
• CPC Class Codes: G02B 19/0028 refractive and reflective surfaces, e.g. non-imaging catadioptric systems
• CPC Class Codes: G02B 19/0085 for use with both a detector and a source , e.g. in a transceiver, G02B19/009, G02B19/0095 take precedence
• CPC Class Codes: G02B 26/105 with one or more pivoting mirrors or galvano-mirrors G02B26/101 takes precedence

Abstract

A LADAR has adjustable operational parameters to accommodate surveillance of a particular site. The LADAR includes a controller, a laser source governed by the controller to generate a laser beam pulsed at a pulse repetition rate, an optical scanner, a first set of optics, a first drive assembly governed by the controller, a second drive assembly governed by the controller, a light detector, a second set of optics for guiding laser echo pulses, and a processor coupled to the light detector to accommodate surveillance of the particular site.

Claims

1. A laser radar (LADAR) having adjustable operational parameters to accommodate surveillance of a particular site, said LADAR, comprising:

a controller;

a laser source governed by said controller to generate a laser beam pulsed at a pulse repetition rate;

an optical scanner;

a first set of optics for guiding said pulsed laser beam from said laser source to said optical scanner;

a first drive assembly governed by said controller for operating said optical scanner to direct said pulsed laser beam through an azimuth field of regard;

a second drive assembly governed by said controller for operating said optical scanner to direct said pulsed laser beam through an elevation field of regard;

a light detector;

a second set of optics for guiding laser echo pulses returned from said azimuth and elevation fields of regard to said light detector which converts said laser echo pulses into electrical echo pulses representative thereof; and

a processor coupled to said light detector for receiving said electrical echo pulses and operative to process said electrical echo pulses to generate a range map of the combined azimuth and elevation fields of regard to accommodate surveillance of said particular site.

2. The LADAR of claim 1, further including:

a data entry device coupled to said controller for entering data into said controller which is operative, based on said entered data, to adjust operational parameters thereof in governing said laser source and first and second drive assemblies;

wherein the controller is operative to accept entered data of a maximum range for the LADAR at the particular site; and

wherein based on the entered maximum range, the controller is operative to adjust the pulse repetition rate to a desired pulse repetition rate for governing the laser source.

3. The LADAR of claim 2, wherein:

the controller is operative to adjust all azimuth scan time based on the desired pulse repetition rate of the laser source; and

the controller governs the first drive assembly to operate the optical scanner to direct the pulsed laser beam through a single scan of the azimuth field of regard at said azimuth scan time.

4. The LADAR of claim 3, wherein the controller is operative to adjust the azimuth scan time based on a function of the azimuth field of regard, an azimuth spacing between laser pulses as the pulsed laser beam is directed through the azimuth field of regard, and the desired pulse repetition rate.

5. The LADAR of claim 3, wherein:

the controller is operative to accept entered data of a time frame for scanning the pulsed laser beam through both of the azimuth and elevation fields of regard; and

based on the entered maximum range and time frame, the controller is operative to adjust the elevation field of regard for governing the second drive assembly.

6. The LADAR of claim 3, wherein:

the controller governs the first drive assembly to operate the optical scanner to direct the pulsed laser beam through multiple scans of the azimuth field of regard in a single scan of the elevation field of regard; and

the controller is operative to adjust the elevation field of regard based on a function of the entered frame time, the adjusted azimuth scan time, and an elevation spacing between the multiple scans of the azimuth field of regard.

12. The method of claim 1, wherein the elevation field of regard is adjusted based on a function of the entered frame time, the adjusted single azimuth field of regard scan time, and an elevation spacing between the multiple scans of the pulsed laser beam through the azimuth field of regard.

7. A method of operating a laser radar (LADAR) with adjustable operational parameters to accommodate surveillance of a particular site, said method comprising:

entering data based on said surveillance of the particular site into said LADAR;

adjusting a pulse repetition rate, a single azimuth field of regard scan time, and an elevation field of regard of said LADAR as a function of said entered data;

generating a laser beam pulsed at said adjusted pulse repetition rate;

scanning said pulsed laser beam through the adjusted elevation field of regard;

scanning said pulsed laser beam through multiple azimuth fields of regard during said scan of the adjusted elevation field of regard, said pulsed laser beam being scanned through each azimuth field of regard at said adjusted single azimuth field of regard scan time;

receiving laser echo pulses returned from said azimuth and elevation fields of regard;

converting said received laser echo pulses into electrical echo pulses representative thereof; and

processing said electrical echo pulses to generate a range map of the combined azimuth and elevation fields of regard to accommodate surveillance of said particular site.

8. The method of claim 7, wherein:

the step of entering data includes entering data of a maximum range for the LADAR at the particular site; and

the step of adjusting includes adjusting the pulse repetition rate of the laser beam based on the entered maximum range.

9. The method of claim 8, wherein the step of adjusting includes adjusting the single azimuth field of regard scan time based on the adjusted pulse repetition rate of the laser source.

10. The method of claim 9, wherein the single azimuth field of regard scan time is adjusted based on a function of the azimuth field of regard, an azimuth spacing between laser pulses as the pulsed laser beam is scanned through the azimuth field of regard, and the adjusted pulse repetition rate.

11. The method of claim 7, wherein:

the step of entering data includes entering data of a time frame for scanning the pulsed laser beam through both of the azimuth and elevation fields of regard and a maximum range for the LADAR at the particular site; and

the step of adjusting includes adjusting the elevation field of regard based on the entered maximum range and time frame.

13. A laser radar (LADAR) having adjustable operational parameters to accommodate surveillance of a particular site, said LADAR comprising:

a controller operative to adjust operational parameters of said LADAR to accommodate surveillance of said particular site;

a laser source governed by said controller to generate a laser beam pulsed at an adjustable pulse repetition rate;

an optical scanner;

a first set of optics for guiding said pulsed laser beam from said laser source to said optical scanner;

a first drive assembly governed by said controller for operating said optical scanner to direct said pulsed laser beam through an adjustable elevation field of regard;

a second drive assembly governed by said controller for operating said optical scanner to direct said pulsed laser beam through multiple azimuth fields of regard during said scan of the elevation field of regard, said pulsed laser beam being scanned through each azimuth field of regard at an adjustable single azimuth field of regard scan time;

a light detector;

a second set of optics for guiding laser echo pulses returned from said azimuth and elevation fields of regard to said light detector which converts said laser echo pulses into electrical echo pulses representative thereof; and

a processor coupled to said light detector for receiving said electrical echo pulses and operative to process said electrical echo pulses to generate a range map of the combined azimuth and elevation fields of regard to accommodate surveillance of said particular site.

14. The LADAR of claim 13, wherein the optical scanner comprises a scan mirror for reflecting the pulsed laser beam through the azimuth and elevation fields of regard.

15. The LADAR of claim 14, wherein the second drive assembly comprises a motor mechanically linked to the scan mirror for rotating the scan mirror through the azimuth fields of regard.

16. The LADAR of claim 14, wherein the first drive assembly comprises a motor mechanically linked to the scan mirror for rotating the scan mirror through the elevation field of regard.

17. The LADAR of claim 14, wherein:

the optical scanner comprises a counter rotating Risley prism pair assembly disposed in an optical path of the pulsed laser beam between the first set of optics and the scan mirror; and

the first drive assembly is operative to rotate the pair of Risley prisms in relation to each other to cause said scan mirror to reflect the pulsed laser beam through the elevation field of regard.

18. The LADAR of claim 17, wherein the scan mirror and Risley prism pair assembly are linked to rotate in azimuth together.

19. The LADAR of claim 14:

further including a cylindrical chamber;

wherein the scan mirror is disposed within the chamber to rotate in azimuth with said chamber; and

wherein the second drive assembly comprises a torque ring motor disposed about said chamber for rotating said chamber and scan mirror disposed therein through the azimuth fields of regard.

20. The LADAR of claim 13, wherein each azimuth field of regard is three hundred and sixty degrees.