Laser radar scanning system

• US 5,200,606 A
• Filed: 07/02/1991
• Issued: 04/06/1993
• Est. Priority Date: 07/02/1991
• Status: Expired due to Term

• Current Assignee: Lockheed Martin Corporation (Martin Marietta Corporation)
• Original Assignee: LTV Missiles and Electronics Group
• Inventors: Flowers, Edward M., Krasutsky, Nicholas J., Minor, Lewis G.
• Primary Examiner(s): Nelms, David C.
• Assistant Examiner(s): Lee, John R.
• Application Number:
  US07/724,794
• Time in Patent Office: 644 Days
• Field of Search: 250/216, 250/203.2, 250/203.3, 250/234, 250/235, 250/236, 356/4, 356/4.5, 356/5
• US Class Current: 250/216
• CPC Class Codes: F41G 7/2213 maintaining the axis of an orientable seeking head pointed at the target, e.g. target seeking gyro
• CPC Class Codes: F41G 7/2246 Active homing systems, i.e. comprising both a transmitter and a receiver
• CPC Class Codes: F41G 7/2293 using electromagnetic waves other than radio waves
• 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 7/481 Constructional features, e.g. arrangements of optical elements
• CPC Class Codes: G01S 7/4817 relating to scanning
• CPC Class Codes: G01S 7/484 Transmitters
• CPC Class Codes: G02B 27/106 for splitting or combining a plurality of identical beams or images, e.g. image replication
• CPC Class Codes: G02B 27/108 for sampling a portion of a beam or combining a small beam in a larger one, e.g. wherein the area ratio or power ratio of the divided beams significantly differs from unity, without spectral selectivity
• CPC Class Codes: G02B 27/1093 for use with monochromatic radiation only, e.g. devices for splitting a single laser source
• CPC Class Codes: G02B 27/143 using macroscopically faceted or segmented reflective surfaces
• CPC Class Codes: G02B 27/283 used for beam splitting or combining

Abstract

An apertured mirror permits an outgoing, transmitted laser beam to pass and reflects a return, reflected beam onto a detector array.

Claims

1. Apparatus for splitting reflected light from transmitted light, comprising:

an optical system operable to transmit a first, diverging beam of light along a first axis and to receive a second, reflected beam coaxial with the first beam, the second beam having greater cross-sectional area than the first beam, said optical system including

a splitter mirror lying in a plane at an angle to the first axial and having an off-center aperture coaxial with the first beam, the aperture being smaller in area than the second beam, and the mirror being sized to reflect a substantial portion of the second beam.

2. A laser scanning system, comprising:

a. a laser light source operable to emit a laser beam along a first optical path;

b. a turning mirror being positioned to redirect the laser beam along a second optical path;

c. a mirror having an aperture therein, the aperture being off-center and located in the second optical path such that the redirected laser beam passes therethrough; and

d. a scanning mirror being positioned in the second optical path to scan the redirected laser beam passing through said aperture along a third optical path.

4. The system, as set forth in claim 2, wherein:

the scanning mirror positioned to receive reflected light from the laser beam along the third optical path and redirect the reflected light along the second optical path toward the apertured mirror; and

the apertured mirror is positioned to receive the reflected light along the second optical path and to redirect a substantial portion of the received reflected light along a fourth optical path.

5. The system, as set forth in claim 4, further comprising:

e. collection optics being positioned to receive the substantial portion of the received reflected light along the fourth optical path.

6. The system, as set forth in claim 5, wherein the collection optics comprise:

a filter being positioned to receive the substantial portion of the received reflected light and to deliver filtered light having a preselected wavelength;

condensing optics being positioned to receive the filtered light and to deliver a focused beam of the filtered light;

a fiber optic bundle having a first end and a second end, the first end of the fiber optic bundle being positioned to receive the focused beam; and

a detector array being coupled to the second end of the fiber optic bundle, the detector array converting the focused beam into an electrical signal.

3. A method of transmitting and receiving laser light comprising the steps of:

a. generating a laser beam;

b. passing the laser beam through an off-center aperture in a receiving mirror;

c. scanning the laser beam in a scan pattern to reflect the beam off a target;

d. receiving light of the laser beam reflected from the target; and

e. reflecting the received light off the receiving mirror.

7. The method, as set forth in claim 3, further comprising the steps of:

collecting the received light reflected off the receiving mirror; and

converting the collected light into an electrical signal correlative to a position of the target.

8. The method, as set forth in claim 7, wherein said step of converting comprises:

filtering the collected light;

focusing the filtered light; and

directing the focused light onto a fiber optic bundle, the fiber optic bundle being coupled to a detector array, the detector array converting the focused light into an electrical signal.

9. A laser scanning system comprising:

a laser light source operable to emit a laser beam;

a mirror having an aperture therein, the aperture being off-center with respect to said mirror and being positioned to pass said laser beam therethrough;

a scanning device being positioned to receive said laser beam passing through said aperture, said scanning device redirecting said laser beam along a predetermined path; and

an afocal Cassegrainian telescope being positioned to receive said redirected laser beam from said scanning device, said telescope transmitting said laser beam toward a target and receiving reflections of said transmitted laser beam from said target.

10. The system, as set forth in claim 9, wherein said telescope comprises:

a primary mirror having a forwardly facing reflective surface and having a central aperture therein; and

a secondary mirror having a rearwardly facing reflective surface, said primary mirror and said secondary mirror being positioned relative to one another with said forwardly facing reflective surface facing said rearwardly facing reflective surface.

11. The system, as set forth in claim 10, wherein said redirected laser beam from said scanning device passes through said aperture in said primary mirror, reflects off of said rearwardly facing reflective surface of said secondary mirror onto said forwardly facing reflective surface of said primary mirror, and reflects off of said forwardly facing reflective surface of said primary mirror toward said target.

12. The system, as set forth in claim 11, wherein said received reflections of said transmitted laser beam from said target reflect off of said forwardly facing reflective surface of said primary mirror onto said rearwardly facing reflective surface of said secondary mirror, and reflect off of said rearwardly facing reflective surface of said secondary mirror through said aperture in said primary mirror and onto said scanning device which transmits said received reflections to said mirror.

13. The system, as set forth in claim 9, further comprising:

a beam segmenter being positioned between said laser light source and said mirror to receive said laser beam, said beam segmenter splitting said laser beam into a plurality of beams and delivering said plurality of beams to said scanning device by passing said beams through said aperture in said mirror.

14. The system, as set forth in claim 13, wherein said plurality of beams are arranged in a fan-shaped array.