Optical Coherent Transients for Real-Time Atmospheric and Large Aperture Correction

Directed Energy Solutions (DES) proposes a technology program for the development of advanced atmospheric and large aperture correction using optical coherent transients (OCTs). The proposed system utilizes dynamic spatial-spectral holography on aninhomogeneously broadened transition to do image correction / tracking and has the potential to produce phase conjugate signals for high Strehl pointing. The proposed corrector will be able to compensate for both atmospheric and large aperture distortionsat rates well beyond those of conventional mechanical or nonlinear optical correction methods. Other advantages include large fields of view, low thresholds (100s of photons or nW), high efficiencies (reflections > 150%), excellent fidelity, and theability to perform real-time analog optical signal processing. The proposed image correction system will be based upon the 1S0 to 3P1 transition at 791 nm in barium gas. This specific system has advantages for rapid refresh rates (MHz), long coherencetimes, and under the proper experimental conditions can be highly efficient. An inexpensive, robust phase conjugator and image corrector has several possible military and commercial clients. These include possibility of use on the Airborne Laser (ABL) orthe Space Based Laser (SBL). By utilizing large lightweight membrane mirrors in conjunction with a dynamic nonlinear optical beam control method such as OCT phase conjugation, payload weight and logistic costs can be drastically reduced. This technologyis expected to leverage large, lightweight beam expanders which besides ABL and SBL have other commercial targets. These include basic directed energy transfer using lasers, satellite communication systems and surveillance. Agencies such as the NRO, NSA,or NASA would be potential clients for such a system. Because of their dynamic nature, target tracking is a natural extension of OCTs. A low cost, compact and efficient target tracking system has several potential applications including use for trackingplanes at commercial airports, use in satellite tracking systems, as well as use in automated landing systems for unmanned aerials. These types of pointing systems would have high accuracy and allow direct free space laser communications with satellites.This means higher communication rates can be achieved as well as the potential to power these satellites from ground installations.