Abstract: A Michelson-type interferometer which includes apparatus for producing a suitable collimated interferometer input beam; a beam splitter and recombiner for first splitting the input beam into two beams which have components arranged to travel along parallel forward paths and then to recombine them into a single output beam as they are returned along reverse paths to the beam splitter and recombiner; an OPD scanner for scanning the optical path difference between the two split beams travelling along said paths while substantially maintaining the parallelism between the components, and a beam reverser common to the parallel beam components for reversing their direction of travel along the reverse paths and returning them for recombination into the single output beam at the beam splitter and recombiner.

Abstract: There is described an improvement for an apparatus employing a plurality of operational elements adapted to cooperate for producing an electrical signal representing the variation of an ordinate quantity with respect to an abscissa quantity changing at a controlled rate. At least one of said elements requires an adjustment during operation such as is capable of causing spurious transients in the electrical signal. The apparatus further comprises a filter for filtering the electrical signal before feeding the signal to a suitable utilization device such as a recorder. The improvement includes control means which operate to interrupt the ordinate quantity signal and cut off the filter response prior to any element adjustment. There is disclosed means for storing the output of the filter at cut off and for memorizing the point along the impulse characteristic of the filter at which cut off takes place.

Abstract: Apparatus for controlling the width of an adjustable slit in response to the product of two variable functions, one of which is programmed, which includes at least one adjustable optical slit; slit width programming apparatus for producing a first displacement that is a logarithmic function of the instantaneous slit width conforming to a predetermined program; antilogarithm generating elements for producing a second displacement that is the antilogarithm of the first displacement; a phase adjusting mechanism for controlling the phasing between the first displacement and the second displacement; slit width selection apparatus operative on the phase adjusting mechanism for controlling the phasing in accordance with a given slit width selection; and actuating elements responsive to the second displacement and operative on the optical slit for controlling its width.