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The Air Force Research Laboratory/Directed Energy Directorate (AFRLIDE) via the ALVA (Applications of Lidars for Vehicles with Analysis) program installed in late 2000 a wideband, 12J 15Hz CO2 laser radar (ladar) on the 3.67 meter aperture AEOS (Advanced Electro-Optics System) telescope. This system is part of the Maui Space Surveillance System (MSSS), on the summit ofHaleakala, Maui, HI. This ladar adopts the technology successfully demonstrated by the first generation HI-CLASS (fflgh Performance ço2 kadar surveillance sensor) operating on the nearby 0.6 meter aperture Laser Beam Director (LBD) and developed under the Field Ladar Demonstration program jointly sponsored by AFRL/DE and the Army's Space and Missile Defense Command.The moderate power (-4 80 watts) HI-CLASS/AEOS system generates multiple, coherent waveforms for precision satellite tracking and characterization of space objects for 1 m2 targets at ranges out to 10,000 km. This system also will be used to track space objects smaller than 30 cm at ranges to 2,000 km. A third application of this system is to provide data for developing satellite identification, characterization, health and status techniques. This paper will discuss the operating characteristics and innovative features of the new system. The paper will also review recent results in support of AF needs, demonstrations, experiments, as well as planned activities that directly support applications in the DoD, scientific, and commercial arenas.

Mode-locked CO2 lasers have been developed which can produce long coherent pulse trains consisting of many narrow subpulses. This laser waveform may be used to numerically generate range-Doppler images (inverse synthetic aperture radar images) of a target wherein the Doppler spread of a spinning target is used to create a synthetic cross-range target dimension. The narrow micro-pulse temporal width provides good range resolution, and the long coherent pulse train provides good frequency resolution of the (cross-range) target Doppler spread. In this paper we examine the algorithms and imaging capabilities of this waveform as implemented for the FLD and Hi-CLASS laser radar (ladar) systems which are now being installed in the AMOS facility on Mt. Haleakala, Maui and in an aircraft testbed. INTRODUCTIONThe U.S. Army, Space and Strategic Defense Command, and the U.S. Air Force, Phillips Laboratory, are developing high power CO2 lasers under the Field Ladar Demonstration (FLD) and High-performance CO2 Ladar Surveillance Sensor (Hi-CLASS) programs. These lasers may be operated in either the natural 'pulse-tone" waveform or in a mode-locked "pulse-burst" waveform depending on the desired measurements and targets. A first generation ladar system is being installed in an aircraft, and a second generation ladar system is being installed at the Air Force Maui Optical Station (AMOS) on Maui using a 60 cm telescope with beam director. This paper addresses the algorithms and capabilities of the FLD/Hi-CLASS mode-locked laser waveform (pulseburst) mode of operation: the narrow mode-locked laser pulses of less than 2 ns duration provide good range resolution, and the long coherent pulse train of greater than 10 gus, with selectable duration, provides good frequency resolution. This good frequency resolution allows a measurement of the target's Doppler spread as a function of the target's range extent and can thus be used to form a synthetic image of a spinning target in a single pulse. Images of non-spinning or slowly spinning targets can be constructed using tomographic imaging techniques, which requires many "looks", has been previously discussed in reference one. GENERATION OF THE MODE-LOCKED CO, LASER WAVEFORMWhen a laser is mode-locked, many longitudinal laser modes are lasing simultaneously inside the laser resonator, and these modes are all in-phase or "phase-locked". As a result, outside the resonator the E-field is the sum of the individual mode E-fields which results in a string of narrow pulses. The instantaneous E-field is given by the real part of the summation 40 ISPIE Vol. 2702 0-8194-2076-X/96/$6.00Downloaded From: http://proceedings.spiedigitallibrary.org/ on 06/23/2016 Terms of Use: http://spiedigitallibrary.org/ss/TermsOfUse.aspx

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The jgh Performance O2 Ldar Lurveillance Lensor system (HI-CLASS) is a state-ofthe-art coherent ladar system which will provide precision tracking and high resolution imaging at the Air Force Maui Optical Station (AMOS). System development is occurring in 3 phases representing increasing hardware/software complexity and system capability. The recently-completed Phase I HI-CLASS system employs a compact, pulsed, coherent CO2 oscillator, a heterodyne receiver, and signal recorder coupled to the AMOS O.6m Laser Beam Director (LBD) to demonstrate target (satellite) acquisition and tracking, illumination, return signal detection, signal recording, and off-line processing for range and range rate extraction and range-amplitude imaging. A description of the Phase I satellite ranging and ground-based remote sensing tests verifying the FLD system operating concept will be presented. The cooperative target range and range rate measurements, as well as imaging precursor demonstration, will be discussed. The talk will include a discussion of the 21 km demonstration of remote sensing using natural terrain returns. Results generated on phase I data with the phase II algorithm will also be described. INTRODUCTIONThe HI-CLASS system, encompassing a coherent, high power CO2 transmitter and a receiver-processor coupled to existing beam directors and associated subsystems, will be capable of state-of-the-art target measurements at the United States Air Force Maui Optical Station (AMOS). These measurements will include precision trajectory determination and high resolution range-Doppler image generation. The system, scheduled for completion in late 1996, is being developed in three phases.Phase I involved the initial demonstration of a complete, pulsed, 100 watt class ladar system with an off-line data processing capability. This effort culminated with a series of ladar tests employing sun-lit cooperative (retro-equipped) targets (GEOS-C and LACE) which yielded satellite range and range rate as a function of time. A series of tests with a wide bandwidth waveform (pulse-burst) also provided an initial demonstration of the system imaging resolution.Phase II , a brass-board oscillator and receiver-processor to extract real-time range and range rate data and to record satellite image data for post-mission analysis is now being tested at AMOS. Phase III will incorporate the full-power, kilowatt system (oscillatoramplifier) for real-time trajectory and image data generation. + This paper is an update of SPIE paper 2702-07 presented at the SPIE conference in San Jose in January, 1996. As such, it contains a review of material previously published along with new material generated since the previous publication date. O-8194-2129-4196/$6.QQ SPIE Vol. 2748 / 309 Downloaded From: http://proceedings.spiedigitallibrary.org/ on 06/24/2016 Terms of Use: http://spiedigitallibrary.org/ss/TermsOfUse.aspx