Abstract: The apparatus is an earth horizon crossing indicator used in a spacecraft attitude control system, which uses power from a self-contained battery rather than power from the spacecraft electrical system. The battery is typically of the lithium thionyl chloride type. This reduces the weight and complexity of the spacecraft attitude control system and allows the resources of the spacecraft electrical system to be used for other devices.

Abstract: A process for making an infra-red detector array wherein an array of m * n first electrodes is formed on a substrate and a layer of plastic material having a polarization sensitive to infra-red radiation is deposited over the electrodes. The layer is partitioned into individual films each over an associated first electrode and second electrodes are positioned on the films on the side opposite to the associated first electrodes.

Abstract: A thermal detector is made from a pair of electrodes and a plastic material disposed therebetween which material has a polarization sensitive to IR radiation. Preferably the detector is formed on a substrate with the plastic material being deposited by spin-casting. The material is a copolymer of TrFE and PVDF. The detector may be partitioned into an array of sensors and used in an apparatus wherein the image of an object is projected onto the array and a chopper is used to block the image from the sensors at regular intervals.

Abstract: The attitude of a satellite is determined by using an array of IR detectors receiving an image of space and the Earth. The detectors are positioned so that at least one detector monitors the radiance from the Earth's horizon and a second detector monitors a region of the Earth adjacent to said horizon. The output of the first detector is compensated for variations in the radiance of the Earth by using the output of the second detector.

Abstract: The attitude of a satellite is determined by using an array of IR detectors receiving an image of space and the Earth. The detectors are spaced so that at least in a central zone, the sun will not enter the optical field of more than one detector. The signals from each detector are monitored and if a signal is very high, indicating that the sun's image is falling on the detector, that signal is ignored.

Abstract: A temperature sensor assembly for monitoring railroad car wheels includes an array of temperature detectors arranged to generate a temperature profile of the wheel. The array may be formed integrally with imaging elements and signal conditioning elements on a single IC chip. The assembly may be arranged to monitor the wheel either transversely or in parallel to the direction of wheel movement.

Abstract: An intrusion detection system includes an array of infrared radiation-sensitive elements, each element comprises first and second spaced electrodes between which pyroelectric material is positioned, and each element is operative to produce a voltage proportional to the rate of change of infrared radiation incident thereon. A pair of oppositely poled detector elements is connected to a first signal processing channel and a second pair of oppositely poled detector elements is connected to a second signal processing channel. The system also includes coincidence means such that an alarm output in response is produced in response to concurrent application of intruder signals of opposite polarity to the two signal processing channels.

Abstract: A dual pyroelectric crystal sensor suitable for infrared intruder alarms and the like having two separate closely spaced identical pyroelectric crystal detectors connected in parallel opposition. The sensor includes a single ended field effect transistor amplifier with the entire sensor encapsulated in a TO-5 can. The two crystals each have one end cemented to a ceramic substrate in a cantilevered fashion, permitting shock or vibration to affect each crystal equally. Therefore, voltages due to the piezoelectric responses of the crystals are equal and cancel. If both crystals are irradiated by a common heat source, the pyroelectric generated voltages will cancel. If either crystal is irradiated separately, an output voltage will be produced.

Abstract: A dual pyroelectric crystal sensor, connected electrically in series opposition to provide ambient temperature compensation, drives a single ended amplifier. The load resistor for the sensor is a center tapped high megohm resistor with the center tap connected to the common electrode connections between the dual crystals to bleed off static charges that build up on the sensor due to the very high impedance of the crystal material.

Abstract: A pyroelectric detector comprising a body of pyroelectric material having a front surface for receiving radiation, a rear surface, a relatively thin coating of radiation absorbing and transmitting and electrically conducting material applied to the entire front surface, and a pair of relatively thicker areas of radiation reflecting and electrically conducting material applied to the rear surface in spaced-apart relation. Two heat sensitive charge generators are defined in the two regions of the pyroelectric body between the coating on the front surface and the two areas on the rear surface, and output electrical leads are attached to the two areas on the rear surface. When radiation is absorbed by either of the heat sensitive charge generators, an electrical current flows in a circuit connected to the output leads thereby providing an indication of the radiation.