SYSTEM FOR LASER DETECTION WITH ENHANCED FIELD OF VIEW

• US 20150177383A1
• Filed: 03/21/2013
• Published: 06/25/2015
• Est. Priority Date: 09/13/2012
• Status: Active Grant

• Current Assignee: The United States Of America As Represented By The Secretary Of The Army
• Original Assignee: US Army Research Laboratory (Government of the United States of America)
• Inventors: Ruff, William C., Stann, Barry Lee, Giza, Mark M., Lawler, William B.
• Granted Patent: US 9,678,209 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• 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 7/4816 of receivers alone
• CPC Class Codes: G01S 7/4861 Circuits for detection, sampling, integration or read-out
• CPC Class Codes: G02B 26/0833 the reflecting element being a micromechanical device, e.g. a MEMS mirror, DMD G02B26/0825 takes precedence; micromechanical devices in general B81B
• CPC Class Codes: G02B 6/06 the relative position of the fibres being the same at both ends, e.g. for transporting images

Abstract

A system comprising a laser for transmitting a beam of light towards a target area; a controller for controlling the output of the laser; a receiver for collecting reflected pulses of light reflected from the target area, the receiver comprising a plurality of receive elements, each of the receive elements having a different field of view; a combiner for combining the outputs of the receive elements into one composite signal of the target area; an interface circuitry for converting the composite signal into an image; display unit displaying output from interface circuitry.

Claims

1. A system comprising:

a laser for transmitting a beam of light towards a target area;

a controller for controlling the output of the laser;

a receiver for collecting reflected pulses of light reflected from the target area, the receiver comprising a plurality of receive elements, each of the receive elements having a different field of view;

a combiner for combining the outputs of the receive elements into one composite signal of the target area;

an interface circuitry for converting the composite signal into an image;

display unit displaying output from interface circuitry.

2. The system of claim 1, wherein the receive elements comprise a plurality of lenses and a plurality of sensors coupled to said plurality of lenses, and wherein each sensor comprises a photosensitive region and outputs a photocurrent;

a plurality of microwave amplifiers, wherein each amplifier is coupled to a sensor and amplifies said photocurrent;

a plurality of feedback circuits, wherein each feedback circuit is coupled to an input and output of a microwave amplifier and raises the bandwidth of a circuit comprising said sensor and said microwave amplifier; and

wherein the combiner is a microwave combiner that combines the photocurrent from each of said plurality of microwave amplifiers to a combined output.

3. The system of claim 1 wherein the combiner produces a summation of the outputs of the receive elements.

4. The system of claim 1, wherein the controller comprises a MEMS mirror and wherein the receive element comprises a lens and an InGaAs PIN photo detector.

5. The system of claim 1, further comprising an analog-to-digital converter coupled to the interface circuitry and at least one processor, wherein input from the interface circuitry is sampled to produce sampling data.

6. The system of claim 5, wherein the at least one processor comprises a field programmable gate array for processing sampling data from the analog-to-digital converter and wherein the at least one processor operates to control the laser in generating said pulses of light.

7. The system of claim 5, wherein the at least one processor comprises a first-in-first-out memory storing sampling data from the analog-to-digital converter.

8. The system of claim 1, wherein said transmitter comprises a microelectromechanical system mirror to direct pulses of light.

9. The system of claim 8, wherein the at least one processor controls the microelectromechanical system mirror.

10. The system of claim 8, further comprising a telescope coupled to the microelectromechanical system mirror, wherein said pulses of light generated from said laser are reflected from the microelectromechanical system mirror is amplified by said telescope and further comprising a high voltage amplifier producing analog voltages that controls a pointing direction of the microelectromechanical system mirror and wherein a digital-to-analog converter is coupled to the high voltage amplifier and at least one processor is coupled to the digital to analog converter, and wherein the at least one processor generates a digital signal to control the pointing direction of microelectromechanical system mirror.

11. An apparatus for receiving pulses of light from a Laser Detection and Ranging (LADAR) transmitter comprising:

a plurality of lenses;

a plurality of sensors coupled to said plurality of lenses, wherein each sensor comprises a photosensitive region and outputs a photocurrent;

a plurality of microwave amplifiers, wherein each amplifier is coupled to a sensor and amplifies said photocurrent;

a plurality of feedback circuits, wherein each feedback circuit is coupled to an input and output of a microwave amplifier and raises the bandwidth of a circuit comprising said sensor and said microwave amplifier; and

a microwave combiner combining said photocurrent from each of said plurality of microwave amplifiers to a combined output.

12. The apparatus of claim 11, wherein the microwave amplifier comprises a wideband monolithic microwave integrated circuit amplifier.

13. The apparatus of claim 11, wherein each of said plurality of sensors comprises an InGaAs PIN photo detector.

14. A ladar system comprising:

a pulse laser generating pulses of light;

a transmitter transmitting pulses of light toward a target;

a receiver for collecting light reflected from said target, the receiver comprising;

a plurality of receive elements;

each receive element comprising a lens and a sensor coupled to the lens, each sensor comprising

a photosensitive region and outputting a photocurrent;

an amplifier for amplifying said photocurrent;

an electrical switch operating to select a predetermined receive element containing the amplified photocurrent;

a power divider splitting the amplified photocurrent between a high gain channel and a low gain channel;

a radio frequency (RF) interface operatively connected to the high gain and low gain channels;

at least one processor operatively connected to the RF interface; and

a display unit displaying output from the at least one processor.

15. The system of claim 14 further comprising:

a plurality of microwave amplifiers for amplifying the photocurrent, wherein each amplifier is coupled to a sensor;

a plurality of feedback circuits, wherein each feedback circuit is coupled to an input and output of a microwave amplifier and raises the bandwidth of a circuit comprising the sensor and said microwave amplifier.

16. The system of claim 14 wherein the system comprises a rotorcraft advanced surveillance and collision avoidance system used for landing rotary aircraft at night in areas containing obstacles.

17. The system of claim 14 wherein a 3-D image of the landing zone and obstacle size is provided on the display unit for viewing by the pilot of the rotorcraft.

18. The system of claim 16 wherein the plurality of receive elements are operatively connected to a fiber optic bundle and the sensor comprises an array of detectors, and amplification and summing electronic circuits, and wherein the fiber optic bundle magnifies the light collection area of the detector array and gathers light monotonically over an approximately 60°

FOV, and wherein each detector in the array then converts the light signal into an electrical signal which is amplified and electrically summed to produce a single output voltage.