Abstract: A module, capable of being mounted on a printed circuit board, containing optical components necessary for optical correlation and a unique folded light path technique for conversion from a Vander Lugt optical correlator to a joint-transform optical correlator, or visa versa, with no electronic changes required. The folded optical path permits a polarizing filter to be positioned in the beam path reflected by a filter SLM but before a correlation detector means when the correlator is in a Vander Lugt mode and permits the polarizing filter to be removed, and an auxilliary mirror or other optical components positioned in the beam path to eliminate the filter SLM and to direct the beam path toward the correlation detector means when the optical correlator is to become a two-cycle joint-transform optical correlator and simultaneously match the Fourier transform plane to the detector plane of the detector means.

Abstract: The present invention is directed to a purified polyalkylsiloxane composition having a boiling point, under atmospheric conditions, of less than about 250.degree. C. and containing high boiling impurities, including siloxanes and silanol-terminated siloxanes, that have boiling points, under atmospheric conditions, of greater than about 250.degree. C. in a total concentration of less than 14 ppm. The present invention is further directed to a method of producing a purified polyalkylsiloxane composition, having a boiling point, under atmospheric conditions, of less than about 250.degree. C., by distilling a polyalkylsiloxane starting material containing high boiling impurities having boiling points, under atmospheric conditions, of greater than about 250.degree. C. in a total concentration of at least 14 ppm, under conditions effective to produce a purified polyalkylsiloxane composition having a boiling point under atmospheric conditions of less than about 250.degree. C.