LADAR TRANSMITTING AND RECEIVING SYSTEM AND METHOD

• US 20110085155A1
• Filed: 10/08/2009
• Published: 04/14/2011
• Est. Priority Date: 10/08/2009
• Status: Active Grant

• Current Assignee: United States Of America As Represented By The Secretary Of The Army (Government of the United States of America)
• Original Assignee: United States Of America As Represented By The Secretary Of The Army (Government of the United States of America)
• Inventors: Stann, Barry Lee, Lawler, William B., Giza, Mark M.
• Granted Patent: US 8,081,301 B2
• Time in Patent Office: Days
• US Class Current: 356/5.09
• CPC Class Codes: G01C 3/08 Use of electric radiation detectors

Abstract

A compact LADAR transmitting and receiving apparatus includes a pulse laser generating pulses of light; a transmitter collimating and directing the pulses of light toward a target; a receiver collecting reflected pulses of light, the reflected pulses of light having been reflected from the target, the receiver comprising a tapered fiber bundle; a sensor operatively connected to the tapered fiber bundle, where the sensor comprises a photosensitive region and outputs a photocurrent; an amplifier amplifying the photocurrent; and a power divider splitting the amplified photocurrent between a high gain channel and a low gain channel; a RF interface accepting the high gain channel, the low gain channel, and an undelayed sample of a pulse of light generated from the pulse laser as input; a processing unit accepting output from the RF interface; and a display unit displaying output from the processing unit.

Claims

1. A compact Laser Detection And Ranging (LADAR) system comprising:

a pulse laser generating pulses of light;

a transmitter collimating and directing said pulses of light toward a target;

a receiver collecting reflected pulses of light, said reflected pulses of light having been reflected from said target, said receiver comprising;

a tapered fiber bundle;

a sensor operatively connected to said tapered fiber bundle, wherein said sensor comprises a photosensitive region and outputs a photocurrent;

an amplifier amplifying said photocurrent; and

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

a radio frequency (RF) interface accepting said high gain channel, said low gain channel, and an undelayed sample of a pulse of light generated from said pulse laser as input;

a processing unit accepting output from said RF interface; and

a display unit displaying output from said processing unit.

2. The LADAR system of claim 1, wherein said pulse laser comprises an Erbium fiber laser.

3. The LADAR system of claim 1, wherein said amplifier comprises a microwave amplifier.

4. The LADAR system of claim 1, wherein said sensor comprises an InGaAs PIN photo detector.

5. The LADAR system of claim 1, further comprising an analog-to-digital converter (ADC) coupled to said RF interface and said processing unit and sampling input from said RF interface to produce sampling data.

6. The LADAR system of claim 5, wherein said processing unit comprises a field programmable gate array (FPGA) processing sampling data from said ADC.

7. The LADAR system of claim 5, wherein said processing unit comprises a first-in-first-out (FIFO) memory storing sampling data from said ADC.

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

9. The LADAR system of claim 8, wherein said processing unit controls said MEMS mirror.

10. The LADAR system of claim 8, further comprising a telescope coupled to said MEMS mirror, wherein said pulses of light generated from said pulse laser are reflected from said MEMS mirror is amplified by said telescope.

11. The LADAR system of claim 8, further comprising a high voltage amplifier producing analog voltages that controls a pointing direction of said MEMS mirror.

12. The LADAR system of claim 11, further comprising a digital-to-analog converter (DAC) coupled to said high voltage amplifier.

13. The LADAR system of claim 12, wherein said processing unit is coupled to said DAC, and wherein said processing unit generates a digital signal to control said pointing direction of said MEMS mirror.

14. The LADAR system of claim 1, wherein said processing unit controls said pulse laser in generating said pulses of light.

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

a tapered fiber bundle;

a plurality of sensors coupled to said tapered fiber bundle, 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.

16. The apparatus of claim 15, wherein said feedback circuit comprises a single capacitor, a single resistor, and a single inductor.

17. The apparatus of claim 15, wherein said feedback circuit comprises an LC circuit.

18. The apparatus of claim 15, wherein said microwave amplifier comprises a wideband monolithic microwave integrated circuit (MMIC) amplifier.

19. The apparatus of claim 15, wherein each of said plurality of sensors comprises an InGaAs PIN photo detector.

20. A method of processing pulses of light from a Laser Detection And Ranging (LADAR) transmitter, said method comprising:

receiving said pulses of light via a tapered fiber bundle;

producing a plurality of photocurrents, wherein each photocurrent is produced from a sensor coupled to said tapered fiber bundle and each sensor comprises a photosensitive region to output said photocurrent;

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

providing 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;

combining said plurality of amplified photocurrents using a microwave combiner, wherein the number of inputs said microwave combiner accepts is as least as great as the number of microwave amplifiers; and

processing and displaying said combined output.