Abstract: A method is provided for greatly increasing the ratio of direct sunlight to earthshine in a sun sensor used on a spacecraft which is orbiting the earth and is used for the attitude determination of spacecraft with respect to the sun illuminated earth. The sun sensor is provided with a detector in which radiation applied thereto is restricted to a spectral region where the earth's atmosphere is extremely absorbent. Therefore, the detector only receives radiation in that spectral region directly from the sun, while any reflected light from the earth in the selected spectral region is absorbed by the earth's atmosphere, thereby never reaching the detector. One suitable spectral region is the ultraviolet absorption band from 200-290 nm and a UV enhanced silicon detector would be used in the sun sensor.

Abstract: A temperature measuring apparatus is provided for determining the temperature of a target material to be measured as compared with the temperature of a spaced reference source which has a temperature control for controlling the temperature of the reference source. A differential radiation detector having a first detector exposed to the target material and a second detector which is shielded from the target material and exposed to the reference source provides a differential output or error signal which is used to control the temperature of the reference source. When the reference source temperature is the same as the target, the temperature of the reference source is read out which is the temperature of the target material regardless of the emissivity. The differential radiation detector is positioned in spaced relation to the target material and is focused onto the target and the reference material and the error signal generated is used for controlling the temperature of the reference source.

Abstract: Selective thermal examination of a target is provided by scanning the field of view of an infrared detector over predetermined areas of a target. The selection is made by a plurality of infrared fibers having first and second ends with the first ends being stationarily mounted in a fixed array suitable for being scanned by the detector or a detector coupled to each first end which are electrically scanned, while the second ends of the infrared fibers are directed by the user to selected areas of the target which are desired to be thermally examined. The infrared detector or detectors are then scanned over the first ends of the infrared fibers in the fixed array for sequentially thermally examining the selected areas of the target. The selected areas may be changed simply by rearranging and redirecting the second ends of the infrared fibers with respect to the target areas desired to be examined.

Abstract: A scanning horizon sensor for indicating orientation by sensing a line of discontinuity in optical radiation in a field of view between a reference body and outer space is provided in which a scanning turret is mounted on one end of a motor shaft of any conventional design or make. A detector is positioned on the optical axis of the horizon sensor for detecting optical radiation applied thereto by the scanning turret generating detector signals in accordance with the intensity of the optical radiation applied. The motor shaft is provided with a small hole drilled axially through the motor shaft which houses an optical fiber which serves to transfer the focal point from one end of the motor shaft to the other where a stationary lens focuses the radiation emitted from the outer end of the optical fiber onto the detector.

Abstract: A visible-ultraviolet horizon sensor and a method for using the same are provided for obtaining attitude information from a satellite. A plurality of detectors selectively responsive to scattered sunlight in the visible and ultraviolet spectral bands view the earth's disc at a plurality of equally spaced locations around the earth. The detectors are scanned across the earth's disc at a plurality of locations thereby generating electrical signals in response to the intensity of visible-ultraviolet radiation from the crescent or fully illuminated earth's disc. Logic circuitry is provided for processing the electrical signals applied thereto from the detectors for producing attitude information for the satellite which is indicative of the satellite's position with respect to the earth.

Abstract: A furnace burner flame monitoring method and apparatus are provided for controlling the burner fuel mixture in order to operate a furnace at maximum burning efficiency. A radiometer having an infrared detector views the flame and detects infrared radiation emitted from the flame. A filter wheel is interposed between the infrared detector and the flame for transmitting at least three different, discrete, infrared radiation bands from the flame to the detector with the detector thereby generating at least three signals in response to radiation received from the three infrared radiation bands. A control parameter is derived using a ratio of at least two of the signals from the infrared radiation bands which are compensated for flame length using a third of the signals generated by the infrared detector. The control parameter may then be utilized for controlling the fuel/air mixture which is burned for thus monitoring and maintaining the furnace at maximum efficiency.

Abstract: A common path interferometer is provided using one or more roof mirrors for effecting an optical path delay required to generate an interferogram of a target signature. The optical arrangement using the roof mirror separates the beam of radiation transmitted from the target to produce a fixed delay between the separated beams and, by rotating the roof mirror, a variable delay between the beams is obtained without leaving the target, thus generating an interferogram between the two interfering beams. The resultant interferogram is converted to a spectrum using conventional inverse Fourier transform techniques.

Abstract: An infrared vidicon system having capacitive type target elements is provided with a means for modulating the target scene with a duty cycle of less than 50% and the reading of the target scene in a predetermined sequence when modulation is not being applied to the vidicon tube. The sequentially read target scene is stored and continuously played back to prevent flicker. This operation allows signal buildup, because the target scene is not discharged every frame.This vidicon system also reduces the non-uniformity of responsivity across the surface of the target of the tube by illuminating the target by an adjustable uniform source of infrared radiation.

Abstract: An infrared line scanning instrument is provided which scans a single line in a field of view of the instrument. The scan is performed by a scanning mirror which is transparent in the visible and reflective in the infrared region of the spectrum. The infrared radiation is applied to an infrared detector which feeds a display in the form of a light-emitting diode array to light an element in the array in accordance with the amplitude of the IR irradiance seen by the instantaneous field of view throughout the scan. The display is superimposed from the back side of the scanning mirror upon the visible field of view seen by the observer and/or a camera. The instrument thus generates a record of the thermal profile of a single line of a viewed target which is spatially correlated with its location on the target.