Abstract: A method for producing a number of microprisms from a plate of material includes the steps of blocking the plate onto a wedge and cutting a number of fiducial grooves in the wedge which are used in a subsequent step to determine the depth to which a polishing operation is continued. Using the method of the present invention, microprisms measuring approximately 375 microns in width and approximately 5 centimeters in length have been produced.

Abstract: Apparatus for inserting and removing several filters from an optical path and for determining at all times the instantaneous positional relationship of each filter with respect to the optical path includes a set of filters mounted on a carrier which is attached to a resonant piezoelectric system, and further includes reference tracks also located on the carrier and extending in the direction of the oscillatory motion and including a sequence of binary indicia progressing in the direction of the oscillatory motion. The reference tracks are read optically to produce a series of binary electrical signals which are processed to yield the instantaneous position of the carrier and filters with respect to a fixed optical path.