Upgrades to DELTAS NRC (Defense Laser Target Signatures Code) for the evaluation of advanced ladar technologies

Abstract

DELTAS<SUB>NRC</SUB><SUP>TM</SUP> is a laser radar signature modeling and simulation code that was developed to evaluate potential LADAR systems for defense applications. DELTAS<SUB>NRC</SUB><SUP>TM</SUP> strength is in its flexibility. The user can create scenarios with realistic targets (the target model is based on constructive solid geometry) and real materials, and model coherent or direct detection LADAR systems at any wavelength (limited only to availability of material reflectance information). This paper focuses on recent improvements to the direct and coherent detection imaging capabilities of the code. These improvements were mandated by the BMDO Discriminating Interceptor Technology Program (DITP) which requires LADAR system models for the next generation of LADAR imaging systems on an interceptor platform. We introduce upgrades to the range-Doppler imaging algorithms that improve the fidelity of the laser cross section calculation and the range-Doppler image. We describe a model that introduces ambiguity in direct detection angle- angle-range images as a result of pulse duration and detector bandwidth. A direct detection receiver model has also been implemented. This model introduces optical modulation transfer functions and receiver noise to the direct detection images. The result of these improvements is an end-to-end LADAR simulation which can be used as a stand alone code or as part of a suite of sensor models capable of generating signatures which can be used for discrimination algorithm development, system analysis, etc. Demonstrations of these improvements as applied to DITP are presented, and a discussion of current applications of DELTAS<SUB>NRC</SUB><SUP>TM</SUP> in simulations such as Synthetic Scene Generation Model is included.