Description:
TECHNOLOGY AREA(S): Sensors, Electronics, Battlespace
OBJECTIVE: Design, fabricate, and test laser detection and ranging (LADAR) sensor laser and detector components for 3-D imaging. The technologies should be designed to support operations from a platform with tight size weight, power, and cost (SWAP-C) constraints.
DESCRIPTION: The AF has a need to develop sensors to support Globally Integrated Intelligence, Surveillance, and Reconnaissance (GIISR) and Global Precision Attack (GPA) capabilities. This includes the development of high sensitivity, very narrow field of view optical sensors for target identification. Typical sensing scenarios cue the LADAR to an object or location to collect a sequence of return pulse measurements. This measured data may be processed for immediate display in the cockpit, downlinked to an image analyst, and/or sent to an automatic or aided target recognition system. Current linear mode and Geiger mode receivers in production or under development provide good sensitivity and clocking rates in large format arrays, as indicated in Reference 1 and 3. Recent linear mode receivers are designed to provide clock rates on the order of nanoseconds, while Geiger mode receivers an order of magnitude faster. Pixel pitch of production receivers are < 100 um, while newer development nears 30 um. Sensitivity of large array linear mode receivers has not reached the capability of counting photons. Ranging performance and sensitivity are primary drivers in the receiver. In an effort to improve LADAR focal plane arrays (FPA), this topic seeks to reduce the size of the unit cell in the readout integrated circuit (ROIC) of a linear mode or Geiger mode LADAR and improve detector sensitivity of avalanche photodiodes (APD), minimizing detector pitch while improving sensitivity and range precision. Of interest are new design ideas for timing circuits and noise suppression. The goal of the unit cell design is to develop a high bandwidth (BW) detector with single photon detection sensitivity, capable of providing 2-D imagery, with high dynamic range for generation of 3-D point clouds with improved range estimation performance. It is envisioned that innovation in the detection logic and timing circuitry may address this challenge, however all approaches are of interest. Performance goals include noise equivalent input < 10 photons, single photon sensitivity, detection BW of GHz to THz at short scene depths, capable of imaging scene depths from 30 m to over 500 m, provide data to support video frame rates of > 20 Hz, in a 1024 x 1024 format or larger array with pixel pitch < 30 um operating in the 1 to 2 um wavelength region. Low crosstalk, large dynamic range > 10 bit, cooling, and damage threshold are considerations. A focus on the development of APDs or ROIC is acceptable, with a requirement of developing a path toward integration and completion of a full LADAR receiver. Initial design should be 16 x 16 format or larger. The detection circuit logic for each unit cell is expected to be the same for the entire array, but could be implemented to provide various detection methods such as first surface, first and last surface, multiple surfaces, etc., supporting imaging though obscurants such as camouflage netting. The LADAR receiver would be capable of being triggered from a pulsed laser, potentially digitizing the outgoing pulse. Cost and SWAP for the full receiver would need to be considered for the final design, where low cost insertion into small unmanned aerial vehicles (SUAV) is a goal. As a threshold, a receiver with supporting electronics should fit into a 4 x 4 x 4 volume, and the cost of a complete LADAR system < $250k. No required use of Government materials, equipment, facilities or data is envisioned.
PHASE I: Develop design ideas for unit cells, detection logic, detectors, and laboratory test configurations for fabrication of a direct detection LADAR receiver and provide circuit simulations. Develop a program plan, Statement of Work (SOW), and performance expectations for a small format 16 x 16 or larger receiver, scalable to 1024 x 1024 or larger. Develop a commercialization plan.
PHASE II: Design, develop, and test a 16 x 16 format or larger LADAR receiver capable of photon counting. Provide laboratory test results, details of test methods. Deliverable includes small format LADAR receiver with supporting electronics for laboratory testing. A focus on the development of APDs or ROIC is acceptable. Develop a program plan, SOW, and performance expectations for a large format receiver capable of insertion into an SUAV, targeting pod, or turret.
PHASE III: Design, develop, and test a large format receiver capable of flight testing a brassboard system in an airborne laboratory type environment. Develop a program plan to integrate into a targeting pod or turret and perform flight testing. Explore integration into SUAVs and fielded systems.
REFERENCES:
1. Reference 1) Michael Jack; George Chapman; John Edwards; William Mc Keag; Tricia Veeder; Justin Wehner; Tom Roberts; Tom Robinson; James Neisz; Cliff Andressen; Robert Rinker; Donald N. B. Hall; Shane M. Jacobson; Farzin Amzajerdian; and T. Dean Cook; Advances in LADAR Components and Subsystems at Raytheon. Proc. SPIE 8353, Infrared Technology and Applications XXXVIII, 83532F (May 1, 2012).
2. Reference 2) Mark A. Itzler; Mark Entwistle; Mark Owens; Ketan Patel; Xudong Jiang; Krystyna Slomkowski; Sabbir Rangwala; Peter F. Zalud; Tom Senko; John Tower; and Joseph Ferraro; Design and performance of single photon APD focal plane arrays for 3-D LADAR imaging. Proc. SPIE 7780, Detectors and Imaging Devices: Infrared, Focal Plane, Single Photon, 77801M (August 17, 2010).
3. Reference 3) Xiaogang Bai; Ping Yuan; James Chang; Rengarajan Sudharsanan; Michael Krainak; Guangning Yang; Xiaoli Sun; and Wei Lu; Development of high-sensitivity SWIR APD receivers. Proc. SPIE 8704, Infrared Technology and Applications XXXIX, 87042H
4. Reference 4) Beck JD, Scritchfield R, and Mitra P, et al; Linear mode photon counting with the noiseless gain hgcdte e-avalanche photodiode. Opt. Eng. 53(8), 081905 (Apr 25, 2014).
KEYWORDS: LADAR, Photon Counting, 3-D Imaging
