Modular Laser Communications Package

We propose a modular laser communications package that is compatible with a wide range of commercial astronomical telescopes.  This package would bolt onto the Nasmyth or Cassegrain focus of the primary telescope. No other modifications are necessary. By adding this package to an unmodified 0.5 m to 1.0 m aperture astronomical telescope,  the telescope is converted into a fully functioning Laser Communications Ground Terminal (LGT).  The bolt-on package (Optics Head) would contain both the transmit and receive optics in a shared aperture configuration, capable of linking with an SDA 3.1 / 4.0  capable LEO satellite terminal.  The user data is transmitted to and from the Optics Head via optical fiber.  The user data interface is a 19in rack mount chassis that also contains all the photonics and amplifiers required by the LGT.  When the package is used with a 0.7 m aperture or larger telescope, then the LGT is capable of communicating with satellites in MEO and GEO orbits. The system comes with an SDA compatible modem, but it is modem agnostic and comes with a fiber optics switching system allowing remote selection of user supplied 1550 nm based optical modems, based on which satellite is being tracked.  The two components: the Optics Head and the Chassis, are controlled using a commercial software package. This package provides remote control of all alignment, calibration, and operation of the LGT, including operation of the telescope and dome.   The software includes advanced Pointing Acquisition, and Tracking algorithms that allow stock astronomical telescopes control systems to track to the accuracies required for bi-directional ground to space laser communication. Advanced metric calibration algorithms allow this package to be used for transportable telescope systems.  The system is designed to be installed by two people in less than a day, with no special tools. Finally, the system is designed with upgrading in mind, these upgrades include: the addition of an Inertial Navigation System for shipboard operation, and operation with high bandwidth (100 Gbps) coherent detection modems.  This is a dual use system, designed to support R&D related to the Proliferated Warfighter Space Architecture (PWSA) as well as university laser communicaitons programs.