Laser beam combiner: applications to space-borne laser communications.

An attractive source for spaceborne laser communications is the directly modulated single-mode GaAs/GaAlAs injection laser. GaAlAs lasers, however, show low power per diode and wide beam divergence. A simple optical concept for a laser beam combiner overcomes diode laser limitations: an array of closely packed parallel collimated laser beams can be handled in an optical system as a single beam. Diffractive spreading causes all bundle beams to overlap in the far field, producing incoherent power addition with 50% power throughput and good far-field performance.

Quasi-microscope concept for planetary missions.

Viking lander cameras have returned stereo and multispectral views of the Martian surface with a resolution that approaches 2 mm/lp in the near field. A two-orders-of-magnitude increase in resolution could be obtained for collected surface samples by augmenting these cameras with auxiliary optics that would neither impose special camera design requirements nor limit the cameras field of view of the terrain. Quasi-microscope images would provide valuable data on the physical and chemical characteristics of planetary regoliths.