The digital star tracker represents a novel departure from previous analog designs in terms of circuit implementation and operational capabilities. As an element of an all-digital spacecraft control system, it combines proven low-level analog signal processing with digital error control and command functions. Additional capabilities that are obtainable with the digital circuitry include programmable intensity threshold gates, commanded electronic pointing control, and an acquisition/control algorithm which minimizes the effects of straylight disturbances. The capabilities inherent in the implementation have been successfully demonstrated in a laboratory model of the instrument.

A high performance, f/1.5 objective lens of 229 mm (9 inches) focal length has been designed and produced for use in a variety of military low light level systems. The latest version of this lens has an integral coaxial 10X beam expander for a 1.06//m laser beam. This allows the lens to be used in a laser rangefinder/target designator role as well as to produce an ambient light image of a 20° field of view for intensification in a direct-view periscope. In this paper, the configuration and optical performance of this new objective lens are described, and the means used to solve some of the unique problems associated with transmission of the laser beam are discussed.

This paper describes an infrared television system used for observing HF continuous chemical laser gas flows. The prime goal for these experiments was the flow visualization of the supersonic free jets provided by the IR HF emissions which were generated by the reaction of hydrogen and fluorine flowing out of selected nozzle configurations. The spatial flow patterns for three IF laser configurations were observed and monitored with this IR television system. The mechanical configuration, optics, and operating parameters associated with each configuration are discussed in this report. The uniformity of the laser medium and the properties of the jet are also described.

A pair of identical multi-aperture templates is described that enable beam collimation to be rapidly evaluated at discrete points over the beam aperture. The technique is independent of the accuracy of other optical components and is inexpensive to implement. A method for fabricating the two templates is indicated, and an application to rapid evaluation of a lens used as a collimator is described.

This is our last issue as Editor of Optical Engineering. We end our brief term with a sense of satisfaction at having introduced several mechanical changes in the Journal which we think improve it, but we are saddened by the fact that SPIE and the Optical Society of America have not yet agreed to merge.