Abstract: The invention relates to a compound blazed optical phase grating. The grating comprises at least two grating sections which are disposed opposite each other in parallel planes. The gratings have grooves which extend parallel to each other. The grating sections have equal grating periods and are movable relative to each other within their planes and perpendicular to the grooves. Over one grating period, the optical path length varies at least substantially parabolically and symmetrically relative to the grating period. The path length varies in such a manner that when both grating sections are symmetrically arranged relative to a common line perpendicular to the grating planes, the optical path length through the compound grating is uniform across the grating. Various optical switches and switching matrixes can be formed by using such compound phase gratings.

Abstract: A chain link conveyor comprises modules pivotally connected to one another. Each module is designed to be molded as a unit, preferably of an organic plastic material and comprises a number of parallel, spaced links having end sections with aligned holes for snap-together pivot rods, and intermediate sections joined by integral cross members to form a rigid, supporting grid.

Abstract: A reframing method for a T1 carrier type pulse code modulation digital data system utilizes the combination of the terminal frame code and the signalling code wherein four consecutive framing bits provide a unique four bit code indicating any one frame of a 12 frame. The method includes the steps of searching for the terminal frame code, synchronizing the framing code generator with the unique 4 bit code, and thereafter checking the three subsequent frames to insure proper reframing.