Abstract: A peristrophic multiplexing system directs a signal light beam and reference light beam onto a selected recording spot in the recording medium. The light beams collectively define a plane of interaction. Either the recording medium or the signal/reference beam are rotated relative to the other through a succession of peristrophic multiplexing angles. Those angles cause relative rotation about an axis that is not perpendicular to the plane of selectivity. The rotation occurs contemporaneously with the modulating of the hologram on the medium.

Abstract: A device for detecting intrusion for security or inventory control purposes includes a mat having loosely superposed metallic foil sheets separated by a sheet of paper or plastic foil dielectric to form a capacitor, and circuitry connected to provide a voltage differential to the capacitor and to detect a change in capacitance caused by weight applied to or removed from the mat. The circuit includes a voltage regulator to regulate the applied voltage differential, a unity gain amplifier to isolate the mat capacitor from change signal amplifier circuitry, a comparator to compare the amplified change signal with user settable thresholds, and a one-shot multivibrator for initiating an alarm signal pulse when one of the thresholds is exceeded. The sheets are preferably aluminum foil backed with plastic film and, in one form, are wrapped one around the other.