Apparatus and method for laser imaging

• US 5,638,164 A
• Filed: 08/09/1995
• Issued: 06/10/1997
• Est. Priority Date: 08/09/1994
• Status: Expired due to Fees

• Current Assignee: Rafael Limited
• Original Assignee: Development Authority Rafael State of Israel--Ministry of Defense Armament
• Inventors: Landau, Uzi
• Primary Examiner(s): Buczinski, Stephen C.
• Application Number:
  US08/512,901
• Time in Patent Office: 671 Days
• Field of Search: 356/5.01, 356/141.1, 356/141.4, 356/376, 356/380, 250/342, 348/164-168, 348/143-148, 382/103, 382/106
• US Class Current: 356/5.01
• 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 7/4802 using analysis of echo signal for target characterisation; Target signature; Target cross-section
• CPC Class Codes: G01S 7/4814 of transmitters alone
• CPC Class Codes: G01S 7/51 Display arrangements

Abstract

This invention discloses a laser imager for imaging a scene having targets comprising a laser scanner operative to scan the scene at a given spacing with a laser beam, a receiver which receives laser light reflected from the scene and determines the range and reflectance of an object reflecting said laser light at various scan positions and control logic which changes the given spacing in response to the determined range.

Claims

1. A laser imager for imaging a scene having targets comprising:

a laser scanner operative to scan the scene at a given spacing with a laser beam;

a receiver which receives laser light reflected from the scene and determines the range of an object reflecting said laser light at various scan positions; and

control logic which changes the given spacing in response to the determined range.

4. A laser imager according to claim 1 wherein the control logic also changes the resolution of said scan in response to the results of a comparison between an array of values at scan positions and a pre-set array of values representing a target signature.

6. A laser imager according to claim 1 wherein the values at scan positions represent target range.

8. A laser imager according to claim 1 wherein the laser source is a GaAs type laser.

10. A laser imager according to claim 1 wherein the laser source is a NdYaG type laser.

12. A laser imager according to claim 1 wherein the laser source is a NdYLF type laser.

16. A system according to claim 10 and also comprising a target shape memory storing target shape information wherein the laser receiver determines candidate target locations by comparing the shape of identified objects with the target shape information.

19. A system according to claim 10 and also comprising a target color memory storing target color information wherein the laser receiver determines candidate target locations by comparing the color of identified objects with the target color information.

2. A laser imager for imaging a scene having targets comprising:

a laser scanner operative to scan the scene at a given spacing with the laser beam;

a receiver which receives laser light reflected from the scene and determines the reflectance of an object reflecting said laser light at various scan positions; and

control logic which changes the given spacing in response to the determined reflectance.

3. A laser imager according to claim 2 wherein the receiver is also operative to determine the range of an object reflecting said laser light at a scan position, and wherein the control logic is also responsive to the determined variations in range and reflectance.

5. A laser imager according to claim 2 wherein the control logic also changes the resolution of said scan in response to the results of a comparison between an array of values at scan positions and a pre-set array of values representing a target signature.

7. A laser imager according to claim 2 wherein the values at scan positions includes target reflectance values.

9. A laser imager according to claim 2 wherein the laser source is a GaAs type laser.

11. A laser imager according to claim 2 wherein the laser source is a NdYaG type laser.

13. A laser imager according to claim 2 wherein the laser source is a NdYLF type laser.

14. A laser imaging system for imaging a scene including targets, the system comprising:

a laser scanner operative to scan the scene at a given resolution with a laser beam;

a laser receiver which receives and analyzes laser light reflected from the scene to determine candidate target locations; and

a laser scanner controller operative to increase the resolution of the scan and to pinpoint the scan to at least one candidate target location.

15. A system according to claim 14 and also comprising a target size memory storing target size information wherein the laser receiver determines candidate target locations by comparing the size of identified objects with the target size information.

18. A method according to claim 14 and also comprising scanning at least a portion of said specific criterion satisfying location at a third resolution higher than said second resolution with said laser beam, only until a highly characteristic target feature is found.

17. A laser imaging method for imaging a scene including targets, the method comprising:

scanning at least a portion of the scene at a first resolution with a laser beam and analyzing the light reflected back, only until a region of interest satisfying at least one general target-characterizing criterion is found; and

scanning at least a portion of said region of interest at a second resolution higher than said first resolution with said laser beam, only until a location satisfying at least one specific target-characterizing criterion is found.

20. A method for 3D imaging of at least a portion of a scene, the method comprising:

generating a 3D representation of a first portion of the scene at a first resolution; and

upon receipt of a control signal, generating a 3D representation of a second portion of the scene at a second resolution.

21. A method according to claim 20 wherein said control signal comprises an indication that a putative target has been encountered.

22. A method according to claim 20 wherein said second resolution is greater than said first resolution.

23. A method according to claim 20 and also comprising the step of generating a 3D representation of a third portion of the scene at a third resolution.

24. A method according to claim 20 wherein generating comprises laser scanning a portion of the scene.