Analysis of Space to Ground Ladar Performance with Non-Traditional Optics

Two major obstacles to space-based LADAR systems are low power returns from targets and limitations on size and weight for transporting large optics into orbit. Signals incur significant losses during roundtrip propagation through the atmosphere and from diffuse scattering off of targets. Models, such as the Laser Environmental Effects Definition and Reference (LEEDR) simulator and High Energy Laser End to End Operational Simulation (HELEEOS) can predict these losses due to the atmosphere and optical components for a variety of atmospheric and environmental conditions across the globe. A transmissometer is used to validate these models. These losses are used to determine if sufficient power would reach a space-borne receiver. One way of ensuring sufficient power is to increase the size of the optic. For this reason, optics in space tend to be large. However, to get desired performance, these optics quickly become prohibitively large and heavy to transport in a satellite. Many non-traditional optics have emerged in recent years that show promise for providing lightweight and volume constrained solutions polymer-based, gradient index (GRIN) optics. These optics were acquired and characterized for their potential use in creating large direct detection LADAR system in space. The results from these characterizations were used to provide feedback on photon link budgets. The feasibility of space based direct detection LADAR is reported from a radiometric standpoint