Abstract: A particular wavelength may be eliminated from the spectrum of a randomly polarized thermally radiative scene by a quarter-wave polarizer and a dielectric dispersive mirror angularly positioned at the Brewster angle for the particular wavelength. The scene radiation is linearly polarized in the plane of incidence of the mirror and the particular wavelength of the scene is transmitted. The other wavelengths of the scene whose indices of refraction are dispersive, i.e., different from the particular wavelength, are reflected and directed to a photodetector, some other radiative detecting device, or a human eye. The invention can thus provide protection from a laser or other high-power optical emitter when used as a counter-measure in a thermally radiative scene.

Abstract: An infrared image is directed onto a transducer having a planar array of absorbing discs, on one side. The discs are supported by a thin membrane which sags or bulges as the discs heat up. The discs thus change their spacings with respect to a partially reflective mirror. The nominal spacing between the discs and mirror is about ¼ wave-length of the infrared radiation, such that absorption is enhanced. The mirror is supported on a transparent substrate through which visible or near-infrared radiation is shown; the mirror/discs thus establish a Fabry-Perot cavity for this radiation, whereby a visible or near-infrared image may be observed or detected as the various discs establish various spacings in accordance with incremental variations in the infrared image. An alternate embodiment uses an electrostatic field to pre-bias the discs toward the mirror and thus to tune or adjuct the sensitivity of the transducer.

Abstract: Two Fabry-Perot interference filters are used as tandum polarizers for a h-power laser beam counter measure in an optical scene. The scene radiation is directed on one polarizer; one plane of polarization of the laser beam is transmitted thereby and the other scene radiation is reflected to the other polarizer. The other polarizer transmits the other plane of polarization of the laser beam and reflects the other scene radiation to a photodetector, such as an image intensifier, infrared imager, television camera tube, or a human eye. The laser beam transmitted by the polarizers is trapped by absorbers and cannot harm the photodetector.

Abstract: An optical material having an index of refraction related to wavelength is placed between the reflectors of a Fabry-Perot cavity employed as an interference filter. The cavity is skewed with respect to the optical path of incident radiation such that the material diverts the optical paths of different spectral lines and the filter response more nearly matches the line spectrum.

Abstract: An optical material having an index of refraction dependent on wavelength of incident radiation is used between the reflectors of an off-normal Fabry-Perot cavity used as an interference filter. External to the cavity, and in the direction of incident radiation, another optical material having an index of refraction dependent on wavelength of radiation is placed. The incident radiation is thus refracted into and within the cavity dependent on its wavelength. By proper choice of the indices of refraction, and other variables, the filter may be designed to exactly match the output spectrum of a line spectrum laser, and to transmit all spectral lines of the laser, but to reflect all other radiation of interest.

Abstract: A filter is constructed consisting of an optical cavity having at least one element which is a square mesh of highly-conductive metal on a transparent substrate. The mesh openings are defined by relatively narrow conductors of the metal. The mesh feature size, as determined by the sum of the conductor width and square size length, is below the diffraction limit for incoming radiation of interest.

Abstract: A trilaminar semiconductor device is placed at an intermediate focus is an optical instrument having a sensitive photodetector. The layers of the device are successively in the form of a two-photon absorber, a sacrificial layer, and a multiple quantum well. The composition of the semiconductor is varied in the layers to achieve the desired bandgap and function.

Abstract: Incident radiation is focussed by a lens into a non-linear optical material whose index of refraction increases with increased radiation intensity. For normal radiation, the radiation freely passes through the nonlinear optical and an optically-switchable material to an other lens. This other lens directs the radiation onto a photodetector. High-intensity radiation, however, is self-trapped in the nonlinear material to form a columnar beam which falls on the optically-switchable material, causes this material to switch, and is reflected thereby.

Abstract: In order to protect a delicate photodetector from high-intensity radiation, such as from a laser, a device for limiting optical power to the detector is interposed between the radiation and the detector. This device has an optical interface that totally reflects high-intensity radiation, but which freely transmits normal (low intensity) radiation to the detector. The interface is between two optical materials, one with a linear index of refraction with respect to radiation intensity, and the other with a non-linear index. At low intensity radiation levels, the two materials have the same indices of refraction, and such radiation is freely transmitted through the interface, but with high-intensity radiation, a mismatch of indices of refraction allows total reflection at the interface.

Abstract: A method of making printed circuit boards in a continuous process. The method uses copper base metal sputtered onto a substrate. This base metal is much thinner than the base metal normally used in printed circuit processes and ultimately allows a greater number of conductors per unit of length to be made on the boards.

Abstract: A liquid crystal modified by the addition of an organic dye is used as a non-linear optical material in two devices which limit the optical radiations to sensitive photodetectors.

Abstract: (S) A first optical material with a linear index of refraction is distributed as particles in a second optical material with an index of refraction dependent on the incident radiation intensity. Below some threshold intensity level the combination of materials is transparent to incident radiation directed toward a sensitive optical detector. Above this level, high-intensity incident radiation induces a change in refractive index of the second material, and the combination is limiting to incident radiation.

Abstract: In order to protect a delicate photo-detector from high-intensity optical radiation such as from a laser, a device for limiting power to the detector is interposed between the radiation and detector. This device has two embodiments and is made such that high-intensity radiation is totally reflected. In the absence of high-intensity radiation, total reflection is frustrated, and desired radiation passes to the detector. Both embodiments use two prisms with parallel surfaces skewed to incident radiation and with a slightly absorbant optical material between the surfaces. Desired radiation normally passes through the prisms and the material to the detector. In one embodiment, the material is a liquid which vaporizes in response to high-intensity radiation, and in the other embodiment, the material expands and pushes the prisms apart. In either case, transmission of radiation halts, and the radiation is totally reflected by a prism skewed surface.

Abstract: A pattern of electrodes, with electrical lead lines to the electrodes, are arried by a thin-film membrane mounted on a frame. The pattern corresponds to a test point pattern on a circuit to be tested. The lead lines go to edge connectors on the frame. In order to test a circuit, the membrane is pushed against the test points by air pressure, such that capacitive coupling occurs between the electrodes and the test points.

Abstract: Incident infrared radiation is focussed through a rotatable disk of germam onto a detector array. The disk has a thickness many times the wavelengths of the incident radiation and is partly covered with a pattern of germanium one-half wavelength of some preselected wavelength of the incident radiation. The pattern is a regular array of mesas, and acts as a phase grating which diffracts incident radiation. The diffracted (or blurred) image on the detector array is used as a reference level for background suppression.

Abstract: An infrared detecting system with a unique detector. The detector consists f an infrared-radiation absorbing layer on one side of thin-film substrate. On the other side of the substrate is a light reflecting layer, with a transducing material on the reflecting layer having a temperature-dependent index of refraction. Infrared radiation falling on the absorbing layer causes a temperature rise in this layer, a consequent rise in temperature of the reflecting layer and the transducing material, and a resulting change in refractive index of the material and a corresponding change in reflectance of the transducing material-reflecting layer combination. A read laser beam directed onto the material is thus reflected in accordance with the infrared radiation on the detector. Alternately, the reflecting layer may be on the same side of the substrate as the absorbing layer. Also, an additional reflector may be used between the reflecting layer and the transducing material.

Abstract: The method includes the steps of making a video recording of an infrared ne, of producing an infrared image from the recording and projecting it onto a screen, and of converting the projected image into a visible image at a user's infrared imager.

Abstract: A waterproof container such as a plastic or treated paper bag is filled w a dry biodegradable vegetable material such as hay, grass clippings, wood shavings, etc. When water is added to the container to wet its contents, the normally-occurring micro-organisms on the vegetable matter decompose it and release heat.

Abstract: A nonlinear optical fluid with radiation-absorbing small particles uniformly suspended in the fluid. For radiation below a threshold value, radiation passes through with slight attenuation. Above the threshold, only a limited level of radiation is passed, the limit being below the damage level of a sensitive optical detector.

Abstract: Apparatus and method for producing laser radiation from an element of a binary (or more complex) compound pumped by microwave energy. The energy causes the compound to dissociate and for the one element of the compound to go to its first excited state, this state being metastable. As the element emits radiation, it reverts to its ground state and recombines to form a compound (which may be the original compound) capable of being dissociated by the microwave energy and repeating the process.