This book is in part an introduction to ladar (or lidar), providing the technical building blocks for understanding the technology, but also provides in-depth coverage of aspects of coherent detection. It covers the mathematical background of traditional direct-detection architecture, including a detailed description of photon-counting detection, which is usually achieved with Geiger-mode APD technology. The book also dives into details of coherent detection architecture, explaining various imaging techniques such as synthetic aperture lidar and vibration sensing lidar. This book can serve as a reference for readers who want to become more acquainted with lidar technology and can also be used as a textbook on the subject.
Raytheon has been funded by DARPA to develop an FPA for single shot eyesafe ladar operation. The goal of the program is to develop new high speed imaging arrays to rapidly acquire high resolution, three dimensional images of tactical targets at ranges as long as 7 to 10 kilometers. This would provide precision strike, target identification from rapidly moving platforms, such as air-to-ground seekers, which would enhanced counter-counter measure (CCM) performance and the ability to lock-on after launch. Also a goal is to demonstrate the acquisition of hidden, camouflaged and partially obscured targets. Raytheon's approach consists of using HgCdTe APD arrays which offer unique advantages for high performance eyesafe LADAR sensors. In this paper we present the progress to date on the program. The detector array is coupled with a Readout Integrated Circuit, ROIC, that captures all the information required for accurate range determination. The two components encompass a hybrid imaging array consisting of two IC circuit chips vertically integrated via an array of indium metal “bumps.” The results of the first phase of the program are given, along with the second phase plans.
Michael Jack, James Asbrock, C. Anderson, Steven Bailey, George Chapman, E. Gordon, P. Herning, Murray Kalisher, Kim Kosai, V. Liquori, Valerie Randall, Joseph Rosbeck, Sanghamitra Sen, P. Wetzel, Maurice Halmos, Patrick Trotta, Andrew Hunter, John Jensen, Terence de Lyon, W. Johnson, B. Walker, Ward Trussel, Andy Hutchinson, Raymond Balcerak
HgCdTe APDs and APD arrays offer unique advantages for high-performance eyesafe LADAR sensors. These include: operation at room temperature, low-excess noise, high gain, high-quantum efficiency at eyesafe wavelengths, GHz bandwidth, and high-packing density. The utility of these benefits for systems are being demonstrated for both linear and area array sensors. Raytheon has fabricated 32 element linear APD arrays utilizing liquid phase epitaxy (LPE), and packaged and integrating these arrays with low-noise amplifiers. Typical better APDs configured as 50-micron square pixels and fabricated utilizing RIE, have demonstrated high fill factors, low crosstalk, excellent uniformity, low dark currents, and noise equivalent power (NEP) from 1-2 nW. Two units have been delivered to NVESD, assembled with range extraction electronics, and integrated into the CELRAP laser radar system. Tests on these sensors in July and October 2000 have demonstrated excellent functionality, detection of 1-cm wires, and range imaging. Work is presently underway under DARPA's 3-D imaging Sensor Program to extend this excellent performance to area arrays. High-density arrays have been fabricated using LPE and molecular beam epitaxy (MBE). HgCdTe APD arrays have been made in 5 X 5, 10 X 10 and larger formats. Initial data shows excellent typical better APD performance with unmultiplied dark current < 10 nA; and NEP < 2.0 nW at a gain of 10.
Maurice Halmos, Michael Jack, James Asbrock, C. Anderson, Steven Bailey, George Chapman, E. Gordon, P. Herning, Murray Kalisher, Louis Klaras, Kim Kosai, V. Liquori, Mike Pines, Valerie Randall, Robin Reeder, Joseph Rosbeck, Sanghamitra Sen, Patrick Trotta, P. Wetzel, Andrew Hunter, John Jensen, T. DeLyon, Charlie Trussell, James Hutchinson, Raymond Balcerak
Raytheon has recently been funded by DARPA to develop an FPA for single shot eyesafe ladar operation. The goal of the program is to develop new high speed imaging rays to rapidly acquire high resolution, 3D images of tactical targets at ranges as long as 7 to 10 kilometers. This would provide precision strike, target identification from rapidly moving platforms, such as air-to-ground seekers, which would enhance counter-counter measure performance and the ability to lock-on after launch. Also a goal is to demonstrate the acquisition of hidden, camouflaged and partially obscured targets. Raytheon's approach consists of using HgCdTe APD arrays which offer unique advantages for high performance eyesafe LADAR sensors. These include: eyesafe operation at room temperature, low excess noise, high gain to overcome thermal and preamp noise, Ghz bandwidth and high packing density. The detector array will be coupled with a Readout Integrated Circuit, that will capture all the information required for accurate range determination. The two components encompass a hybrid imaging array consisting of two IC circuit chips vertically integrated via an array of indium metal 'bumps'. The chip containing the PAD detector array and the silicon signal processing readout chip are independently optimized to provide the highest possible performance for each function.
Hughes Aircraft Co. has been involved with laser range finders and laser radars for over 20 years. This paper tries to summarize some of the typical laser radar sensors and applications in the last few years. The first half of the paper is to give a brief analytical description of the current issues in designing a modem ladar. The second half gives a review of laser sensors that have been developed by Hughes and by other companies highlighting some of the key features of those sensors.
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