Three-Dimensional Landing Zone (3D-LZ) refers to a series of Air Force Research Laboratory (AFRL) programs to develop high-resolution, imaging ladar to address helicopter approach and landing in degraded visual environments with emphasis on brownout; cable warning and obstacle avoidance; and controlled flight into terrain. Initial efforts adapted ladar systems built for munition seekers, and success led to a the 3D-LZ Joint Capability Technology Demonstration (JCTD) , a 27-month program to develop and demonstrate a ladar subsystem that could be housed with the AN/AAQ-29 FLIR turret flown on US Air Force Combat Search and Rescue (CSAR) HH-60G Pave Hawk helicopters. Following the JCTD flight demonstration, further development focused on reducing size, weight, and power while continuing to refine the real-time geo-referencing, dust rejection, obstacle and cable avoidance, and Helicopter Terrain Awareness and Warning (HTAWS) capability demonstrated under the JCTD. This paper summarizes significant ladar technology development milestones to date, individual LADAR technologies within 3D-LZ, and results of the flight testing.
The Three-Dimensional Landing Zone (3D-LZ) Joint Capability Technology Demonstration (JCTD) is a 27-month program to develop an integrated LADAR and FLIR capability upgrade for USAF Combat Search and Rescue HH-60G Pave Hawk helicopters through a retrofit of current Raytheon AN/AAQ-29 turret systems. The 3D-LZ JCTD builds upon a history of technology programs using high-resolution, imaging LADAR to address rotorcraft cruise, approach to landing, landing, and take-off in degraded visual environments with emphasis on brownout, cable warning and obstacle avoidance, and avoidance of controlled flight into terrain. This paper summarizes ladar development, flight test milestones, and plans for a final flight test demonstration and Military Utility Assessment in 2014.
A joint-service team led by the Air Force Research Laboratory's Munitions and Sensors Directorates completed a
successful flight test demonstration of the 3D-LZ Helicopter LADAR Imaging System. This was a milestone
demonstration in the development of technology solutions for a problem known as "helicopter brownout", the loss of
situational awareness caused by swirling sand during approach and landing. The 3D-LZ LADAR was developed by
H.N. Burns Engineering and integrated with the US Army Aeroflightdynamics Directorate's Brown-Out Symbology
System aircraft state symbology aboard a US Army EH-60 Black Hawk helicopter. The combination of these systems
provided an integrated degraded visual environment landing solution with landing zone situational awareness as well as
aircraft guidance and obstacle avoidance information. Pilots from the U.S. Army, Air Force, Navy, and Marine Corps
achieved a 77% landing rate in full brownout conditions at a test range at Yuma Proving Ground, Arizona. This paper
will focus on the LADAR technology used in 3D-LZ and the results of this milestone demonstration.
Direct detection imaging Laser Radar (LADAR) produces 3-dimensional range imagery that can be processed to provide target acquisition and precision aimpoint definition in real time. This paper describes the current status of the Parallel Multichannel Imaging LADAR Receiver (PMR), developed under an SBIR Phase II program by the Air Force Research Laboratory, Munitions Directorate (AFRL/MN). The heart of the PMR is the Multichannel Optical Receiver Photonic Hybrid (MORPH), a high performance 16-channel LADAR receiver card which includes fiber-coupled detectors, pulse discrimination, and range counting circuitry on a 3 X 5 inch circuit card. The MORPH provides high downrange resolution (3 inches), multiple-hit (8 per channel) range and reflectance data for each detector. Silicon (Si) and indium gallium arsenide (InGaAs) pin diode or avalanche photodiode (APD) detectors are supported. The modular PMR uses an array of MORPH circuit cards to form a compact multichannel imaging LADAR receiver with any multiple of 16 channels. A 32-channel system measures 3 X 5 X 1.4 inches and weighs 1 lb. A prototype PMR system is currently undergoing field-testing. This paper focuses on field test results and applications of the PMR technology.
Active imaging laser radars form 3D images which can be processed to provide target identification and precision aimpoint definition in real time. Earlier raster-scanned and pushbroom-scanned 3D imaging laser radar receivers required multiple laser pulses to assemble a complete 3D image frame. Platform/target motion and atmospheric effects caused tearing and jitter in the assembled 3D images, which complicated the subsequent image processing and necessitated the use of stabilized scanning systems. This paper describes the current status of the parallel/multichannel imaging laser radar receiver (PMR) which is being developed under an SBIR Phaser II program by the USAF Wright Laboratories Armament Directorate. The PMR uses an array of multichannel laser radar receivers to form single-pulse, 3D laser radar images, thus eliminating the complex and costly scanning system, and enabling much higher frame rates than were ever before possible. The heart of the PMR is the multichannel optical receiver photonic hybrid (MORPH), a high performance 16-channel laser radar receiver module which uses an array of InGaAs avalanche photodiodes for eyesafe operation. The MORPH provides high downrange resolution, multihit range data for each detector on a compact circuit card. Optical flux is transferred from the receiver focal plane to each MORPH via a fiber optic ribbon cable. An array of MORPHs are plugged into a compact passive backplane, along with a single digital control card (DCC). The DCC, which is the same form factor as the MORPH, synchronizes the MORPHs and transfers the digital range information to the host processor over a standard parallel data interface cable. The system described here illustrates one approach to integrating and packaging high-density photonic arrays and their associated signal processing electronics to yield a compact, low power, scannerless, high performance imaging laser radar receiver, using existing technology.
In 1995, under a USAF SBIR Phase I program, Burns Engineering Corporation investigated the application of new integrated photonics technologies and hybrid manufacturing processes to the miniaturization of an imaging laser radar receiver which has complete receiving and range counting circuitry for each pixel in a 25-by-25 element avalanche photodiode array. The `parallel multichannel' receiver (PMR) is a compact, robust, and modular laser radar subsystem which can produce high resolution 3D range imagery at 1 kHz frame rates without the use of a scanner. The modular PMR is attractive as a common module solution for a wide variety of high performance, low cost, autonomous laser-guided seeker applications. The system described illustrates one approach to integrating and packaging high-density photonic arrays and associated signal processing electronics to yield a high-performance imaging laser radar receiver using existing technology. Burns Engineering has been selected by the USAF to build a benchtop prototype, proof-of-concept demonstrator in a follow-on, SBIR Phase II program.
A pulsed GaAs laser rangefinder is analyzed and designed. Expressions for background and signal power, noise, and signal-to-noise ratio are derived. The effects of pulse rise time, receiver bandwidth, and SNR on probability of detection and range accuracy are discussed. A computer simulation is used to optimize laser power, receiver aperture, and preamplifier bandwidth. A method ofthreshold detection is presented and discussed. Experimental results include receiver preamplifier transfer function and threshold detector performance.
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