LASER RADAR SYSTEM AND METHOD FOR ACQUIRING 3-D IMAGE OF TARGET

• US 20140240691A1
• Filed: 06/12/2013
• Published: 08/28/2014
• Est. Priority Date: 06/14/2012
• Status: Active Grant

• Current Assignee: Electronics and Telecommunications Research Institute
• Original Assignee: Electronics and Telecommunications Research Institute
• Inventors: MHEEN, Bongki, Oh, MyoungSook, Kim, Kisoo, Sim, Jae-Sik, Nam, Eun Soo, Kwon, Yong-Hwan
• Granted Patent: US 9,234,964 B2
• Time in Patent Office: Days
• US Class Current: 356/4.07
• CPC Class Codes: G01S 17/89 for mapping or imaging
• CPC Class Codes: G01S 7/4815 using multiple transmitters
• CPC Class Codes: G01S 7/4818 using optical fibres
• CPC Class Codes: G01S 7/484 Transmitters
• CPC Class Codes: G01S 7/4863 Detector arrays, e.g. charge-transfer gates

Abstract

Disclosed are a laser radar system and a method for acquiring an image of a target, and the laser radar system includes: a beam source to emit the laser beam; a beam deflector disposed between the beam source and the target, and configured to deflect the laser beam emitted from the beam source in a scanning direction of the target as time elapses; and an optical detector configured to detect the laser beam reflected from the target, which is provided a plurality of beam spots having a diameter D_RBS; and a receiving optical system disposed between the target and the optical detector and configured to converge the laser beam reflected from the target, and the optical detector includes a detecting area having a diameter D_DA that satisfies an equation of √{square root over (/2)}×P_RBS+2×D_RBS≦D_DA≦2×D_lens and an equation of (4/π)×λ×F_number<D_RBS<D_lens.

Claims

1. A laser radar system acquiring an image of a target by using a laser beam, comprising:

a beam source to emit the laser beam;

a beam deflector disposed between the beam source and the target, and configured to deflect the laser beam emitted from the beam source in a scanning direction of the target as time elapses;

an optical detector configured to detect the laser beam reflected from the target, which is provided a plurality of beam spots having a diameter D_RBS; and

a receiving optical system disposed between the target and the optical detector and configured to converge the laser beam reflected from the target,

wherein the optical detector comprises a detecting area having a size D_DA that satisfies [Equation 1] and [Equation 2] below, and

√

{square root over (/2)}×

P_RBS+2×

D_RBS≦

D_DA≦

2×

D_lens 

 

[Equation 1]

wherein P_RBS represents a maximum pitch between the beam spots, D_RBS represents the diameter of the beam spot, and D_lens represents a pupil diameter of the receiving optical system, and

(4/π

)×

λ

×

F_number<

D_RBS<

D_lens 

 

[Equation 2]

wherein λ

represents the wavelength of the laser beam and F_number represents an F number depending on the pupil diameter of the receiving optical system.

2. The laser radar system of claim 1, further comprising:

a signal reading unit configured to read a signal output from the optical detector by using information on another location of the target as time elapses, which is used in the beam deflector.

3. The laser radar system of claim 2, further comprising:

an image processing unit configured to calculate distance and/or reflected beam intensity information of the target by using laser beam information read by the signal reading unit and determine a 3-D image of the target by using the calculated distance and/or reflected beam intensity information.

4. The laser radar system of claim 3, further comprising:

a camera configured to acquire a 2-D image of the target,

wherein the image processing unit corrects or synthesizes the determined 3-D target image and the 2-D target image acquired by the camera.

5. The laser radar system of claim 1, wherein:

the optical detector comprises a single detecting area.

6. The laser radar system of claim 1, wherein:

the optical detector comprises two or more divided detecting areas,

wherein, a plurality of signals output from divided detecting areas is combined to be processed as a single output signal.

7. The laser radar system of claim 1, wherein:

the beam deflector periodically deflects the laser beam to viewing points of the target.

8. The laser radar system of claim 1, wherein:

when the laser beam is reflected on one or more locations in the target, one or more coordinate information is obtained by detecting the reflected laser beams.

9. The laser radar system of claim 1, wherein:

the beam deflector comprises a plurality of beam scanning units, and

the respective beam scanning units are disposed to scan the laser beam to different regions or some superimposed regions, or at different angles with respect to the target.

10. The laser radar system of claim 9, wherein:

the respective beam scanning units scan the laser beam in a time-division manner.

11. The laser radar system of claim 1, wherein:

the optical detector comprises a plurality of optical detectors,

wherein, some optical detectors are disposed in parallel or obliquely in order to detect a reflected laser beam which is not detected by the remaining optical detectors.

12. The laser radar system of claim 11, wherein:

the receiving optical system comprises a plurality of receiving lenses having different wide angle characteristics, which are correspond to the plurality of the optical detectors.

13. The laser radar system of claim 1, wherein:

the beam deflector comprises at least any one of a Galvano mirror and a rotary polygon minor, an acousto-optic deflector and a bi-axial driven scan minor, an MEMS scanner, and an MEMS reflector.

14. The laser radar system of claim 1, wherein:

the beam deflector comprises an electro-optic (EO) scanner or a fiber array laser.

15. A method for acquiring an image of a target by using a laser beam in a laser radar system, the method comprising:

emitting the laser beam;

deflecting the laser beam in a scanning direction of the target as time elapses;

converging, by a receiving optical system, the laser beam reflected from the target; and

detecting, by an optical detector, the laser beam converged by the receiving optical system, which is provided a plurality of beam spots having a diameter D_RBS,

wherein the optical detector comprises a detecting area having a diameter D_DA that satisfies [Equation 1] and [Equation 2] below, and

√

{square root over (/2)}×

P_RBS+2×

D_RBS≦

D_DA≦

2×

D_lens 

 

[Equation 1]

wherein P_RBS represents a maximum pitch between the beam spots, D_RBS represents the diameter of the beam spot, and D_lens represents a pupil diameter of the receiving optical system, and

(4/π

)×

λ

×

F_number<

D_RBS<

D_lens 

 

[Equation 2]

wherein λ

represents the wavelength of the laser beam and F_number represents an F number depending on the pupil diameter of the receiving optical system.

16. The method of claim 15, further comprising:

calculating distance and/or reflected beam intensity of the target by using information of the detected laser beam; and

determining an image of the target by using the calculated distance and/or reflected beam intensity.