Abstract: An improved diurnal sun tracking system and methodology for use with a photovoltaic solar collector system mountable on flat roof industrial buildings or multi-unit apartment buildings is provided. The improved tracking system and method rotates or pivots the solar collector system to track the sun during the spring and fall Equinoxes in a first tracking mode, as well as from winter to summer solstices, when the angular rate of the sun's movement does not exactly follow the angular rate at the Equinoxes, in a second tracking mode.

Abstract: A combined diurnal tracking, concentrator, photovoltaic plus domestic hot water solar thermal system is mountable on flat roof industrial buildings or multi-unit apartment buildings for diurnal tracking, and on pitched roofs of single family residences. The systems are configured to reduce the number of solar cells required for given power output, and increased generated heat by a concentration of the sun's insolation on the solar cells. The increased heat is drawn off by anti-freeze fluid circulated in an aluminum extrusion attached to the solar cells and concentrator reflectors for the dual purpose of providing domestic hot water or space heating and maintaining the solar cells cool to enhance their efficiency.

Abstract: An airborne search and rescue scanner is provided to locate a missing person wearing a reflector for reflecting laser energy emitted from a scanner in a high speed aircraft. The scanner and reflector combination enable scanning of a large search area in a relatively short time period. The system is designed to prevent false readings, as for example, sun glint reflected by the reflector, or false alarms resulting from reflections from the terrain being searched and not the reflector worn by the missing person. In an alternative embodiment of the invention, the active laser scanning system is replaced by a passive infrared scanner by replacing the laser scanner with an infrared detector. In this embodiment, it is not necessary for the missing person to wear a reflector.

Abstract: An airborne search and rescue scanner is provided to locate a missing person wearing a reflector for reflecting laser energy emitted from a scanner in a high speed aircraft. The scanner and reflector combination enable scanning of a large search area in a relatively short time period. The system is designed to prevent false readings, as for example, sun glint reflected by the reflector, or false alarms resulting from reflections from the terrain being searched and not the reflector worn by the missing person. In an alternative embodiment of the invention, the active laser scanning system is replaced by a passive infrared scanner by replacing the laser scanner with an infrared detector. In this embodiment, it is not necessary for the missing person to wear a reflector.

Abstract: A three axis attitude readout system for geosynchronous spacecraft operating at geosynchronous and other orbit altitudes has a two axis sun sensor, a two axis Polaris star tracker, and an infrared single axis earth sensor for use when the sun is behind the earth. The three sensors cooperate with each other such that each sensor has characteristics overcoming inherent weaknesses in the other sensors. The overall system results in a highly accurate three axis readout which could not be achieved by using any of the three sensors alone. The sensor system is designed to be of low weight, low volume and low power consumption.

Abstract: An immersed solar concentrator system has a concentrator element for directing light rays onto a solar cell. The solar cell has a surrounding reflective surface for reflecting light rays which are not absorbed by the solar cell but strike the reflective surface. The immersion medium, which is disposed between the solar cell and the concentrator element, has a refractive index for reflecting the reflected light rays, by total internal reflection, in a direction towards the solar cell so that at least some of the reflected light rays are absorbed by the solar cell.

Abstract: A momentum wheel energy storage system employs a semi-passive magnetic bearing. The system provides advantages over chemical electrical storage batteries including enhanced storage life. The use of passive permanent magnetic bearings for radial control in combination with active axial control results in a flywheel energy storage system which eliminates several components of conventional flywheel energy storage systems. The energy storage system can be employed in orbiting spacecraft to provide the dual functions of storage of energy from a spacecraft solar collector and control of spacecraft attitude and attitude stabilization.

Abstract: A solar power system for orbiting spacecraft includes a collector surface and attached mirror which is retained in a coiled position around the outer surface of the spacecraft in its launch mode. The system is deployed from the orbiting spacecraft by releasing restraining straps and permitting the mirror and attached collector surface to automatically uncoil as a result of the resilient spring characteristics of the mirror. During orbit, the deployed system extends from one side or both sides of the spacecraft such that the mirrored surface faces the sun. Heating pipes are pivotably disposed between the mirror and the collector surface to also function as spacing struts. The collector surface covered with photovoltaic solar cells made of silicon or Gallium Arsenide-Phosphide (GaAsP) in a first embodiment of the invention, can be replaced by a flat heat pipe for conducting heat energy to the input of an external heat engine electric generator in a second embodiment of the invention.

Abstract: A sun sensor for use in orbiting satellites provides accurate attitude control yet eliminates the use of complicated optical components. The improved accuracy results from adjustment of the relative positions of a slit or pinhole aperture and a cooperating linear array of photodetector elements to increase the operating range of the sun sensor. Enhanced accuracy is further achieved by the use of a relatively wide slit instead of complicated optical components, in conjunction with a processing procedure which uses the finite angular subtense of the sun to increase the accuracy of the attitude control of the satellite by the sun sensor. A further embodiment of the invention includes a sun sensor device having dual "pinhole" apertures which is particularly useful for attitude control of a spinning satellite.

Abstract: An earth horizon sensor on board an orbiting spacecraft is designed to produce four (4) scans across the earth at geosynchronous altitudes using only two non-visible wavelength (infrared) detectors. The four scans are essentially parallel and permit the earth center to be offset from the null axis of the earth sensor permitting the offset pointing of high gain communication. By providing four scans using only two detectors, components are minimized and reliability is improved. The four scans are generated with only two detectors by using both the front and rear surfaces of a rotating scanning mirror.

Abstract: A sun sensor for use in orbiting satellites provides accurate attitude control yet eliminates the use of complicated optical components. The improved accuracy results from adjustment of the relative positions of a slit or pinhole aperture and a cooperating linear array of photodetector elements to increase the operating range of the sun sensor. Enhanced accuracy is further achieved by the use of a relatively wide slit instead of complicated optical components, in conjunction with a processing procedure which uses the finite angular subtense of the sun to increase the accuracy of the attitude control of the satellite by the sun sensor. A further embodiment of the invention includes a sun sensor device having dual "pinhole" apertures which is particularly useful for attitude control of a spinning satellite.

Abstract: An earth sensor primarily for use at geosynchronous altitude measures Pitch, Roll, as well as Yaw. Pitch and Roll are obtained from the sun illuminated earth crescent viewed through a pinhole by a CID video camera. A circular mask positioned in front of the pinhole blacks out the center 10 degrees of the earth. A beam splitter receives visible radiation from the earth crescent through the pinhole and combines it with energy from a lens system aimed at Polaris and beta Ursa Minor and/or gamma Cepheus and projects radiation from such polar stars onto the CID detector. Yaw is obtained by sensing the position of the pole star Polaris.

Abstract: A horizon sensor scans an infrared detector over the earth's horizon generating first (A) and second (B) signals of finite pulse width representing radiation from the fields of view of the infrared detector as it is scanned across the earth's horizon. Signals (A-B) and (A+B)/3 are derived from the first (A) and second (B) signals. The horizon is detected when a threshold is exceeded when the absolute value (A-B) is less than the absolute value of (A+B)/3 whereby the detected horizon is essentially independent of the radiance variations of the earth's horizon. Sun and moon signals appearing in the field of view of the infrared detector are eliminated based on the smaller pulse width of such signals in comparison with the finite pulse width of the first and second signals. The method of radiance compensation can be implemented using a dual field of view for the infrared detector in a horizon crossing indicator sensor where the scanning of the detector is provided by the rotation of the satellite.

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 mortar fire control system for indicating azimuth, elevation and cant alar orientations of a mortar barrel. The system comprises a 3-axis optical head mounted adjacent the mortar barrel which emits light pulses in two predetermined directions, 90.degree. apart, towards aiming stakes. Two aiming stakes located at approximately 50 meters and 100 meters from the mortar are aligned along one of the predetermined directions while a third aiming stake is situated 90.degree. away from the first two aiming stakes and at a distance of approximately 50 meters from the mortar. Each of the aiming stakes is provided with an optical transponder for receiving the light pulses emitted from the optical head and for retransmitting a light pulse to said optical head. The light pulses received by the optical head are converted into digital information representative of the azimuth, elevation and cant angular orientations of the mortar barrel relative to predetermined initial values of each of these three parameters.

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 protection device for an electro-optical detector used in systems for making far field diagnostic measurements of a high energy laser beam comprises a solid silicon cone having a truncated apex which functions as the pin hole aperture for the detector. The large end of the cone has a surface defined by the radius drawn from the cone axis at the truncation. This surface is coated with a reflective attenuation layer which reflects a high percentage of the energy of the incident laser beam entering the pinhole aperture thereby minimizing the absorption of the beam by the cone. The high index of refraction of the solid silicon cone permits large off-axis angles of the laser beam to be directed onto the detector resultingly increasing the field of view of a system using a given detector. The increased field of view allows a closer spacing of a plurality of detectors in the system ensuring a high spatial resolution of the laser beam for a desired field of view.

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 evacuated dual pane window structure is provided for reducing heat loss through the window structure. The window structure comprises a pair of closely spaced panes of glass having a spacing of less than 0.25 inch with a spacer means positioned between and uniformly spaced in the area between the panes, and sealing means such as an O-ring positioned around the perimeter and between the panes of glass. A vacuum pump may be provided for evacuating the area between the panes of glass for reducing thermal losses through the window structure. Reflective coatings may be provided on the inside surfaces of the glass. A plurality of windows of the above structure may be connected by manifold piping to a single vacuum pump which is actuated by a thermostat when a preset temperature differential exists between the outside and the inside of the building where the windows are used.