Abstract: Interconnection module for connection to other interconnection modules to provide a back plane of any desired size and configuration in electronic data shelf arrangements. The module has optical terminals extending from a front face for signal transmission and reception relationship terminals, preferably optical terminals, for signal interconnection with at lest one other interconnection module. Signal conductors extend from the terminals of the front face to the terminals of the other face. Flat cables are conveniently used to interconnect modules which may be relatively positioned horizontally or vertically spaced or both.

Abstract: A method and apparatus for optically determining the distribution of normal force present at the mating surfaces of an electrical surface connector uses the birefringent properties of a photoelastic material. Photoelastic members are distributed between the two planar surfaces, and plane-polarized, narrow-band wave-length light is coupled into each member with an optical fiber. The light is directed to propagate along a principle strain axis of the photoelastic member. The temporarily birefringent photoelastic material provides a relative propagation delay between vector components of the light in each member which are perpendicular to the propagation direction. The light exiting each member is input to a plane polarizer, the output of which is measured with an intensity meter. The relative delay between the vector components creates a detectable change in intensity at the intensity meter.