Abstract: Spatial acquisition and precision beam pointing functions are critical to spaceborne laser communication systems. In the present invention a single high bandwidth CCD detector is used to perform both spatial acquisition and tracking functions. Compared to previous lasercom hardware design, the array tracking concept offers reduced system complexity by reducing the number of optical elements in the design. Specifically, the design requires only one detector and one beam steering mechanism. It also provides means to optically close the point-ahead control loop. The technology required for high bandwidth array tracking was examined and shown to be consistent with current state of the art. The single detector design can lead to a significantly reduced system complexity and a lower system cost.

Abstract: An array of diode lasers, either a two-dimensional array of surface emitting lasers, or a linear array of stripe lasers, is phase locked by a diode laser through a hologram which focuses the output of the diode laser into a set of distinct, spatially separated beams, each one focused onto the back facet of a separate diode laser of the array. The outputs of the diode lasers thus form an emitted coherent beam out of the front of the array.

Abstract: A multi-rate digital command system is disclosed which uses the composite signal of a .mu.-type ranging system as a subcarrier to transmit range codes and data from a station to a receiver where the range codes are sequentially phase modulated on a subcarrier of frequency f.sub.sc by one of its own subharmonics as follows:C.sub.i = f.sub.sc .sym. f.sub.sc /2.sup.iand data is phase modulated on a selected ranging component, C.sub.i, where i is a number selected from the sequence 1, 2 . . . n in which the ranging components are transmitted. A range cleanup loop in a spacecraft locks the phase of a locally generated reference component C.sub.i to a received ranging component C.sub.i and retransmits the component to a ground station. When the inverse phase, C.sub.i , of a ranging component is received and detected, the cleanup loop is modified to demodulate phase modulated command symbols while continuing tracking the same ranging component C.sub.i.