Lockheed Martin Corporation

Other

Ltv Aerospace & Defense Company

Vought Corporation

Ltv Aerospace and Defense

Westinghouse Electric Corporation

Dayton D Eden

Thomas R Schimert

William E Case

Richard C McKee

James D Billingsley

Leslie L Thompson

An apparatus includes a link receiver having a detector array configured to receive radiation from a remote communication device, where the detector array includes multiple detectors. Each detector includes a horn receiver configured to capture the radiation using an antenna positioned in or proximate to a throat of the horn receiver, where the antenna is coupled to an antenna load. Each detector also includes a bolometer electrically isolated from the antenna load and in thermal contact with the antenna load. The link receiver could include a terahertz camera. The detector array can be located at a focal plane of an optical system configured to receive the radiation through a specified far-field solid angle. The apparatus could also include a link transmitter configured to generate and transmit second radiation to the remote communication device and/or a communication transmitter/receiver configured to communicate with the remote communication device.

Apparatus and method supporting covert communications using terahertz imaging camera

This disclosure describes antenna elements, terahertz detector arrays formed by antenna elements, and dual-mode terahertz imaging systems that operate using terahertz detector array(s). The antenna element includes a horn receiver configured to collect radiation and capture the radiation using an antenna positioned in or proximate to a throat of the horn receiver. The antenna element also includes antenna posts electrically coupled to the antenna and extending through irises in a conducting ground plane and conductive traces electrically coupling the antenna posts to an antenna load. In addition, the antenna element includes a bolometer mounted on a first substrate, where the bolometer is electrically isolated from the antenna load and in thermal contact with the antenna load. The antenna could include a bow tie antenna having first and second arms on a first surface of a second substrate, where the ground plane is on a second surface of the second substrate.

Dual-mode terahertz imaging systems

An infrared radiation detector device has an array of detectors each of which comprises a pattern of parallel detector elements. Each detector produces a pixel signal for an image. The elements of the detector are photoconductive or photovoltaic bandgap materials, and the elements are spaced apart at a dimension which is equal to or less than the wavelength of the radiation to be received. Additional layered structures above and/or below the detector elements provide impedance matching between free space radiation and the radiation impedance of the detector elements to increase the capture of radiation.

Bandgap radiation detector

A method for fabricating an infrared radiation detector is disclosed. The detector utilizes photosensitive segments which are included within elongate members disposed on surface of a dielectric substrate. The elongate members comprise photosensitive detector segments which are located between and contact non-photosensitive segments and the entirety of each elongate member is electrically conductive. The elongate members are preferably offset from each other by less than the wavelength of the radiation and the photosensitive segments within the strips are also preferably spaced apart by less than the wavelength of the radiation. A reflective plane, typically an aluminum layer, is offset from the plane of the detector segments by less than the wavelength of the radiation. Incident radiation is captured by the overall detector structure which includes the reflective plane and the elongate members which include both photosensitive and non-photosensitive segments. The radiation power is transferred to the photosensitive detector segments to produce a detection signal. The detection signals are combined along the length of the elongate members and conveyed through electrical conductors at the ends of the members to produce a composite radiation detection signal. A plurality of detectors can be combined to produce an infrared imager.

Method for fabricating an infrared radiation detector

An electromagnetic wave interactive structure is provided for forming a transmitted electromagnetic wave response which is a function of the frequency of the incident wave. A phase transition material selected from the transition-metal oxides, dynamic nonlinear materials, the rare earth monochalcogenides and the organometallics is provided in geometric relationship with a fixed metallic structure. The phase transition material is then switched between a dielectric phase and a metallic phase to alter the response of the composite structure. Thus, an inductive mesh may be switched to a reflective surface (FIG. 8); an inductive band-pass changed to a reflective surface (FIG. 9); a capacitive band-stop response to an inductive band-pass response (FIG. 10); a capacitive band-stop response changed to a reflective surface (FIG. 11); a capacitive mesh response to an inductive band-pass response (FIG. 12); and a capacitive band-stop response switched to an inductive mesh response (FIG. 13). The ability to switch the response characteristics of an electromagnetic wave interactive structure provides useful applications in such devices as optical hardening systems, agile aperture devices and polarizing devices using bi-refringent structures.

Dynamic filter structures

An infrared detector cell includes a plurality of uniformly spaced linear segments, which make up an optical grating. Each segment is selectively doped across its width to form a photovoltaic diode. The linear segments are ohmically connected between electrical conductors to produce a single cell detection signal. The cell comprises a diffractive resonant optical cavity. An array of cells can produce an infrared image. Cell configurations are illustrated for receiving both single dimension and linearly polarized radiation and two-dimension unpolarized radiation.

Semiconductor photovoltaic diffractive resonant optical cavity infrared

An infrared radiation detector device has an array of detectors each of which comprises a pattern of parallel detector elements. Each detector produces a pixel signal for an image. The elements of the detector are photoconductive or photovoltaic bandgap materials and the elements are spaced apart at a dimension which is equal to or less than the wavelength of the radiation to be received. Additional layered structures above and/or below the detector elements provide impedance matching between free space radiation and the radiation impedance of the detector elements to increase the capture of radiation.

An infrared radiation detector device comprises a dipole antenna mounted on a substrate and connected through blocking contacts to a bandgap detector element. The dipole antenna has a length which is approximately one half the wavelength of the incident infrared radiation. The bandgap detector element has linear dimensions which are each substantially smaller than the wavelength of the detected radiation. A group of detector devices are combined to form an array which can produce a pixel signal for an image. Unlike conventional infrared radiation detectors, the disclosed detector device is capable of producing a usable output signal without the need for cooling below ambient temperature.

Uncooled infrared detector

An infrared radiation detector is disclosed which is fabricated on a dielectric substrate. The detector utilizes photosensitive segments which are included within elongate members disposed on the surface of the substrate. The elongate members comprise photosensitive detector segments which are located between and contact non-photosensitive segments and the entirety of each strip is electrically conductive. The elongate members are preferably offset from each other by less than the wavelength of the radiation and the photosensitive segments within the elongate members are also preferably spaced apart by less than the wavelength of the radiation. A reflective plane, typically an aluminum layer, is offset from the plane of the detector segments by less than the wavelength of the radiation. Incident radiation is captured by the overall detector structure which includes the reflective plane and the elongate members which include both photosensitive and non-photosensitive segments. The radiation power is transferred to the photosensitive detector segments to produce a detection signal. The detection signals are combined along the length of the elongate members and conveyed through electrical conductors at the ends of the members to produce a composite radiation detection signal. A plurality of the detectors can be combined to produce an infrared imager.

Infrared radiation detector

An infrared detector, having improved infrared absorptance and operating performance at or near ambient as well as the cryogenic temperature ranges. The infrared detector, in one embodiment includes a multi-filament HgCdTe detector region mounted upon a CdTe substrate, a metallic reflective region placed in front of, or behind, the HgCdTe detection region forming a resonant layer between the reflective region and HgCdTe. Electrical contacts operable to detect the change in resistance of the HgCdTe detector filaments are connected to the detector region. Embodiment for a back surface illuminated detector device is described for use in the 8 micron to 12 micron, longwave infrared (LWIR) range. Improved operation in the LWIR range at higher temperatures results in detector arrays having decreased cooling needs and infrared detector systems produced with a significant decrease in overall system weight.

Back surface illuminated infrared detector

An optical erasable disk memory system which utilizes duration modulated laser switching is disclosed. The disk storage system utilizes a disk-shaped storage medium which includes a planar substrate and a thin film of phase change material. A substantially transparent optical tuning layer and protective layer are also utilized in the preferred embodiment of the present invention. The phase change material utilized is sensitive to both stress and temperature variations and will change from a first optically discernible phase to a second optically discernible phase at any portion thereof subjected to a temperature in excess of a selected threshold temperature at a particular stress and will change from the second phase back to the first phase at any portion thereof subjected to a stress in excess of a selected threshold stress at a particular temperature. A duration modulated laser is selectively utilized to heat particular portions of both the planar substrate and the thin film of phase change material to increase the temperature of the phase change material above the threshold temperature at those portions. A shorter duration laser pulse is utilized to heat selected portions of the phase change material without permitting the heat to dissipate into the substrate. The heated phase change material expands at a greater rate than the non-heated planar substrate and thereby increases the stress at those selected portions to a stress above the selected threshold stress.

Optical erasable disk memory system utilizing duration modulated laser

A pressure sensitive film display is disclosed having a piezoelectric substrate and a thin film of pressure sensitive phase change material disposed thereon. A film of pressure sensitive material such as samarium sulfide is deposited on a piezoelectric substrate and exhibits a marked increase in reflectance at a region thereof subjected to a pressure in excess of a selected threshold pressure. Three interdigital surface acoustic wave transducers are provided along three edges of the display and are utilized to produce selective surface acoustic wave pulses in the surface of the film. Each surface acoustic wave pulse generates an area of pressure such that an external pressure greater than the selected threshold pressure is generated only at each point where three surface acoustic wave pulses intersect. Circuitry is provided for ensuring that all three surface acoustic wave pulses can intersect at any selected region of the film and the pulsewidth of at least one surface acoustic wave pulse is selectively varied to allow only a selected portion of any selected region to exhibit the increase in reflectance. In this manner the gray level of each selected region may be altered accordingly.

Pressure sensitive film display having multiple gray levels

A random access memory device is disclosed which utilizes phase change materials. The memory device includes two overlapping films of a phase change material which exhibits an optically discernible phase change at any portion thereof which is subjected to a selected external stimulus and which exhibits a hysteresis effect such that any such portion is substantially unchanged after the external stimulus is removed. Various phase change materials are disclosed which respond to changes in pressure, temperature or electric field intensities to vary the transmission characteristics of a selected portion of a film of such material from substantially opaque to translucent. One of the two overlapping films is then utilized to record digital data by changing the phase of the material at selected portions thereof. A single selected portion of the second film is then rendered translucent and utilized in conjunction with a powerful light source and a photodetector to ascertain the phase of a particular portion of the first film which underlies the single selected portion of the second film.

Random access memory device utilizing phase change materials

In an optical radar system a coherent signal is transmitted at a variable position and the return signal, that is, the reflected portion of the coherent signal is received and coherently detected. The transmitter utilizes a scanning laser having an electron beam that impinges upon a variable reflectance mirror that terminates one end of an optical cavity. An oscillating mode is generated within the resonant cavity when the electron beam locally heats the surface of the variable reflectance mirror to create a pixel that reflects light in a diffracted pattern. The receiver utilizes a stable single mode laser to illuminate a variable reflectance surface. A receiver electron beam generates a plurality of receiver pixels at various positions. The diffracted light from each pixel generates a plurality of variable angle local oscillator beams that are summed with the return signal at a beamsplitter. The output of the beamsplitter is applied to the surface of a detector array. One of the local oscillator beams is positioned such that the return signal and the local oscillator beam overlap at one of the detectors in the array to provide coherent detection. The frequency of the first coherent signal and the second coherent signal are sampled by a first and second partially reflecting mirror. A frequency detector detects the output of the first and second partially reflecting mirror to detect the frequency difference between the first and second coherent signal and generate a control signal that adjusts the frequency of the first coherent signal. For heterodyne operation a selected frequency difference is generated whereas for homodyne detection a zero frequency difference is generated. An electronic computer coordinates the position of the scanning laser of the transmitter and the position of the local oscillator beams of the receiver such that one of the local oscillator beams will overlap with each of the corresponding return signals at the detector array. A second electronic computer processes the output of the detector array to provide information about the return signal.

Growing community of inventors

Dallas, TX, United States of America

Dayton D Eden