Abstract: An interference filter is deposited on a high temperature transparent plastic film which passes normal incident radiation below 694 nm and reflects other wavelengths out to 1064 nm regardless of the angle of incidence of the laser radiation applied thereto. The interference filter is optically bonded directly onto a ballistic protective plastic substrate which transmits visible radiation thereby providing a laser shield having ballistic properties as well as laser radiation rejection properties. The ballistic protective plastic substrate may also contain absorbing dyes for absorbing laser radiation in the region of high sensitivity of 400 to 700 nm. The interference filter is then optically bonded directly onto the transparent ballistic protective plastic substrate thereby providing a protective laser shield having ballistic protection properties as well as hybrid filter properties both absorbing and reflecting laser radiation.

Abstract: A horizon sensor which senses the horizon and produces a signal which indicates orientation with respect thereto is provided for scanning the horizon or distant line of discontinuity in optical radiation by a detector sensitive to such radiation and using the signals generated by the detector in crossing the line of discontinuity in optical radiation for attitude control of moving bodies. A scanner for the detector has two successive reflecting elements in optical alignment with the detector for reflectively applying predetermined optical radiation from a scanned field of view which includes the line of discontinuity in optical radiation.

Abstract: A narrow-band filter for absorbing radiation at a wavelength in the range of 9.2 to 10.8 microns and for transmitting radiation in a surrounding 8 to 12 micron band having a high transmission ratio. The filter is comprised of a pure or mixed alkali-halide crystal having optical incidence and transmission surfaces and thiocyanate or borofluoride as an impurity.

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: A selected impurity in a crystal is provided as a narrow-band absorption filter for optical radiation. The crystal lattice constant may be adjusted, for example, by forming a mixed crystal, to adjust the absorption frequency.

Abstract: Three axis attitude information is provided by a horizon sensor for a spin stabilized satellite having an optical system on the spinning member viewing normal to the spin axis with a linear array of detectors in its focal plane which scans a zone around the earth. The detectors are self scanned and sensitive to visible and UV light and respond to the sun illuminated crescent of the earth, moon, stars or other illuminated bodies. Accordingly, a linear array of detectors mounted on a rotating portion of the satellite views a line in space which scans a zone on the celestial sphere and from the position of two celestial objects within this zone such as the earth and the sun, and the known time, pitch, roll and yaw can be established. The system also has an automatic alignment feature in which the array can be accurately aligned with the spin axis and any misalignment can be determined from orbital data and corrections made in flight. With the wide 360.degree.

Abstract: Pitch and roll attitude information of an orbiting body is provided by sensing the discontinuity of optical radiation in a scan field of view between the reference body and outer space using a scanner which simultaneously scans two concentric conical paths through the field of view about the same axis of rotation of the orbiting body. The scanner comprises a scanning mirror split into two halves which are tilted through an angle with respect to each other and are also displaced in phase with respect to each other about the axis of rotation. The scanner may also be a prism having angled faces on opposite sides of the optical axis of the scanner which are also displaced in phase. Either scanner results in having a detector view two instantaneous fields of view simultaneously. An infrared detector receiving the radiation from these two fields of view produces signals which can be used to determine pitch and roll attidue as well as altitude on each scan which identifies four points around the horizon.

Abstract: A radiation detector is scanned over two fan fields of view by first and second cylindrical lenses spaced about the axis of rotation of a common optical element positioned on the axis of rotation. The optical element is rotated about the optical axis by a motor or the rotation of the orbiting body on which the scanner is mounted. In one form the common optical element is a chisel mirror having the first and second cylindrical lenses positioned on opposite sides thereof and tilted at an angle of 45.degree. with respect to the axis of rotation producing two fan fields which are 180.degree. apart in phase. As an alternative the common optical element may comprise a cylinder having the second cylindrical lens positioned along with a bevelled reflective upper surface for producing a vertical fan field.

Abstract: A horizon sensor having a pair of adjacent infrared detectors which view the earth's horizon either statically or by scanning is provided with a second order radiance correction to reduce errors in determining the true position of the horizon due to radiance variations of the earth due to changes in latitude and seasons particularly at lower altitudes. The second order correction is empirically determined from a large number of horizon profiles, and in two illustrative examples for different types of sensors, the correction may be readily obtained from a linear function related to the peak radiance of the horizon profiles.

Abstract: The three-axis angular position of a tetrahedral reflector which is mounted on a platform or element is monitored by first and second optical apparatus aimed at the reflector at equal angles on opposite sides of the axis of the reflective element thereby providing off-axis viewing of the reflective element for monitoring the angular movement of that element. The first optical apparatus is an autocollimator having a source of radiation for producing a beam of radiation which is applied to a beam splitter through a collimating lens which is aimed at the reflector. The return image from the reflector is passed through the beam splitter to a detector. The second optical apparatus may simply be a receiver including a second lens in optical alignment with a second detector with the lens being aimed at the tetrahedral reflector. The second optical apparatus may be in the form of an autocollimator of the same type as the first optical apparatus.

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: The cooled infrared detector of an infrared microscope is scanned over a target specimen at ambient temperature, the signal is stored, inverted and added to subsequent radiance signals derived from subsequent scans of the target to provide a continuous correction for the "Narcissus Effect".

Abstract: A laser shield which absorbs narrow band radiation of a laser beam while transmitting broad band radiation encompassing the narrow band is provided by diffusing a layer of a chromophore selected from one or more porphyrin complexes which have been modified by metals forming a metallo-porphyrin complex. The chromophore or chromophores are combined with a solvent which are mixed for dissolving the chromophores in the solvent to provide a dissolved chromophore solution. A transparent matrix material is dipped or otherwise brought into contact with the solution for a predetermined time period at a predetermined temperature for diffusing the chromophore into the surface of the matrix material which has been softened by the solvent at the elevated temperature to thereby provide a layer of diffused chromophore which absorbs radiation in a narrow band corresponding to the characteristics of the chromophore while passing a substantial portion of all radiation applied thereto.

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 transparent protective laser shield and a method for forming the same are provided in which the shield is adapted to be interposed between a laser beam and a viewer for adjustably absorbing more than one narrow band radiation from laser beams while transmitting radiation in a broader band surrounding the narrow band laser beams. A transparent host material comprising a crystalline or amorphous glassy or plastic material having substantial transmission properties of optical radiation has introduced therein a plurality of chromophores selected from a porphyrin complex which has been modified by a metal providing metallo-porphyrin complexes in the transparent material which absorbs optical radiation at predetermined narrow band wave lengths located within the selected broad band wave length passed by the transparent host material.

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: The inside air temperature, the outside air temperature and the temperature of the inside surface of an exterior structure whose `R` value is to be determined and these values are selectively applied to the `R` value apparatus which stores the inside and outside temperatures as voltage analogs and combines them to provide a first difference signal. The inside temperature analog is also applied to a second combination circuit. After the inside and outside temperature analogs are fed to the apparatus and stored therein, then the inside surface temperature of the structure, such as the wall or ceiling, which is being measured, is applied as an analog voltage to the apparatus. The inside structure temperature analog is combined with the inside room temperature analog to provide a second difference signal which is then divided into the first difference signal in an analog divider, a portion of the output being fed directly to a meter calibrated in `R` values.

Abstract: A family of two axis horizon sensors using the same basic scan technique is provided which achieves a relatively wide altitude range with a minimum of moving parts for performing vehicle attitude control and guidance. The horizon sensor for indicating the orientation of a space vehicle senses a line of discontinuity in optical radiation between a reference planet and outer space in at least two planes using a single sensor which includes a single detector means for detecting the optical radiation. The detector is scanned across the line of discontinuity in at least two planes. The scanner includes a rotary element driven by a single motor having at least two stationary reflecting elements positioned therearound. A phase reference signal generator is coupled to the motor and driven in synchronism therewith for generating at least two reference signals at predetermined points in the scan.

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.