Chirped amplitude modulation ladar for range and Doppler measurements and 3-D imaging

Abstract

ABSTRACT Shipboard infrared search and track (IRST) systems can detect sea-skimming anti-ship missiles at long ranges, but cannot distinguish missiles from slowly moving false targets and clutter. In a joint Army-Navy program, the Army Research Laboratory (ARL) is developing a ladar to provid e unambiguous range and veloc ity measurements of targets detected by the distributed aperture system (DAS) IRST system being developed by the Naval Research Laboratory (NRL) sponsored by the Office of Naval Research (ONR). By using the ladar's range and velocity data, false alarms and clutter objects will be distinguished from incoming missiles. Because the ladar uses an array receiver, it can also provide three-dimensional (3-D) imagery of potential threats at closer ranges in support of the force protection/situational awarene ss mission. The ladar development is being accomplished in two phases. In Phase I, ARL designed, built, and reported on an initial breadboard ladar for pr oof-of-principle static platform field tests. In Phase II, ARL was tasked to design, and test an advanced breadboard ladar that corrected various shortcomings in the transmitter optics and receiver electronics and improved the signal processing and display code. The advanced breadboard will include a high power laser source utilizing a long pulse erbium amplifier built under contract. Because award of the contract for the erbium amplifier was delayed, final assembly of the advanced ladar is delayed. In the course of this year’s work we built a “research receiver” to facilitate design revisions, and when combined with a low-power laser, enabled us to demonstrate the viability of the compone nts and subsystems comprising the advanced ladar. Key Words : Ladar, Lidar, fm-cw, chirped AM, range-Doppler, tracking, 3D imaging, cruise missile, force protection, IRST