Hughes Aircraft Company

USA as Represented by Secretary of the Navy

Slava A Pollack

David B Chang

I-Fu Shih

James E Drummond

Victor Vali

Kenn S Bates

Patrick C Brownrigg

Van O Nicolai

Michael F Berg

Albert J Jicha

Robert Tzeng

Selective emissivity coatings are disclosed for temperature reduction of enclosures such as vehicles and building structures. The coating includes a selective emissivity material such as silicon-oxy-nitride having a desired thermal emissivity function which is high in the 8-13 micron wavelength region, and low elsewhere except in the visible wavelength region. The material provides a mechanism for radiative cooling of the enclosure by converting the blackbody radiation of the enclosure, which would be reflected by the earth's atmosphere, into far infrared radiation which is transmitted by the atmosphere. According to another aspect of the invention, the coating further comprises a semimetal which is reflective of radiation in the near infrared region, thereby reducing the solar heat load on the enclosure. One suitable semimetal is LaB.sub.6. The coating may be applied to the exterior surface of vehicle and building windows, or to the exterior, non-window surfaces of building structures. For the latter, the coating may take the form of a conventional paint to which is added tiny particles of the semimetal and selective emissivity materials to achieve the radiative cooling and reflection of incident infrared radiation.

Selective emissivity coatings for interior temperature reduction of an

A nondestructive noninvasive device and method for testing printed circuit boards (PCBs) through the utilization of a liquid crystal material which visually images the electric fields of the PCBs. Circuit faults resulting in a change of current flow in a PCB produce recognizable changes in observed electric fields. The present invention may be used in a stand-alone mode or as a supplement to other testing techniques.

Liquid crystal electric field tester for circuit boards

Latent fingerprints are detected by upconverting infrared radiation provided by a special dusting powder and digitally imaging the upconverted radiation. In accordance with the principles of the present invention, a real time image of latent fingerprints is obtained by first 'dusting' the print with a powdered upconversion material. The print is then illuminated with 1.55 .mu.m infrared radiation using a fiber optic bundle in the form of a probe. The 1.55 .mu.m infrared radiation is converted into several reradiated wavelength bands by the powdered upconversion material. A charge coupled device or diode matrix detector array converts the image of the fingerprint to digital format for real time display and/or transmission over airwaves. The system is a portable latent fingerprint acquisition system that permits rapid fingerprint evaluation and comparison. A method of detecting fingerprints is also disclosed.

Acquisition and testing of latent fingerprints using upconversion

A miniature infrared test target that comprises a heated four-bar test target operated at a high temperature and a physically separated ambient field operated at ambient temperature. A beamsplitter is disposed relative to the test target and the field in a position to combine and transmit images thereof along a common axis. A lens is disposed along the common axis and forms a combined image of the test target and the field at its image plane. Separation of the test and field targets permits miniaturization of the test target while maintaining a temperature difference between the field and the bars that is proportional to the true temperature difference. The target overcomes the difficulty of maintaining an extremely high temperature gradient in the target. It provides a greater contrast range than that provided by conventional miniature targets. The miniature infrared test target is made with surfaces approximating a blackbody, thereby providing immunity from the Narcissus problem and the effects of complicated environmental changes.

Miniature infrared test target

An improved curing oven using Wellsbach conversion is disclosed. The present invention 10 provides an improved curing oven which cures materials with electromagnetic radiation in the ultraviolet region. The invention consists of a surface 12 lined with a layer of material 14 effective to radiate ultraviolet radiation in response to the application of infrared radiation. In a specific illustrative implementation, the invention 10 includes a second surface 18 overlying the first surface 12 providing a passageway therebetween. The oven temperature is set and maintained by a conventional temperature controller 20. The temperature controller 20 measures the oven temperature and controls a valve 22 which adjusts the gas pressure from a gas supply 24 to a set of oven burners 26. Air is supplied through inlet ports 28 included in the second surface 18.

Curing oven using Wellsbach conversion

A laser incorporating a laser medium disposed within a laser cavity and a pumping arrangement for selectively applying excitation energy to said laser medium. The laser medium contains upconverting material of the type which allows for the exchange of energy between electrons of the lasing ions at a given energy state below the meta-stable initial lasing state so that some of said exchanging electrons are upconverted to energy states at or above the meta-stable initial lasing state. The pumping arrangement applies energy of suitable wavelength and intensity for elevating electrons from energy levels below the given state to that state in sufficient numbers to support substantial upconversion and the resulting lasing.

Upconversion pumped lasers

Full color alphanumeric or image displays are produced by upconverting near infrared radiation into visible light. The display system includes an upconverting screen including a host material doped with rare earth ions. The screen may be divided into pixels which may be slectively excited by infrared radiation to emit visible light of a desired color. An intensity-modulated infrared laser beam is scanned across the surface of the screen to selectively excite the screen pixels and produce the desired image.

Full color upconversion display

A transparent eyelevel stoplight for vehicles is disclosed, which operates on an upconversion principle wherein red light in an otherwise transparent crystal is excited by invisible infrared radiation. The crystal may take the form of a transparent plate or an optical fiber applied to the vehicle rear window. The host crystal material is doped with a suitable rare-earth ion, which when illuminated by infrared energy produces visible light. An infrared laser may be used to illuminate the doped crystal, and is activated by the vehicle brakes. The crystal material is transparent to ordinary visible light and therefore will not obscure the driver's vision.

Transparent eyelevel upconversion stoplight for vehicles

The method of producing at least quasi-continuous lasing operation between initial and terminal lasing states comprising the steps of selecting a laser medium and cavity configuration (lasing frequency) with the laser medium containing upconverting material which provides for the exchange of energy between sufficient number of electrons at the terminal lasing state (manifold) so as to maintain population inversion between the initial and terminal lasing states during the lasing operation; and applying excitation energy of a suitable amount to the laser medium during at least a quasi-continuous time period.

Method of providing continuous lasing operation

Apparatus is provided for measuring the numerical apertures of an optical fiber in the infrared region. The optical fiber is appropriately mounted in accordance with conventional testing standards. Infrared energy is transmitted through the optical fiber. At a predetermined distance from the end of the optical fiber, a conversion screen can be provided for transforming the emitted infrared energy into a lesser wavelength of energy. The energy distribution can be recorded with a detector compatible with the lesser wavelength energy whereby the numerical aperture can be computed from the recorded data.

Apparatus for measuring properties of a laser emission

An improved thermal radiator uses host materials having high internal reflection and scattering co-efficients for improved effectiveness. Selective thermal radiators are used for frequency conversion of incident radiation through the Welsbach effect. A Welsbach material screen is used to convert incident IR radiation into visible radiation, permitting visual observation of IR radiation and facilitating control and monitoring of IR equipment. Welsbach material is also used as a dynamic IR target which converts incident visible radiation into a high resolution IR source pattern. Welsbach material is also employed as a temperature stable material for converting solar radiation into heat.

Selective thermal radiators

A Nernst lamp is used as the pumping means for a solid state laser. The l materials are selected so that the light energy emitted is essentially concentrated in the relatively narrow pump region of the absorption spectrum of the laser crystal. The input power in to the laser is equivalent to that of much higher power lamps operating over a much wider spectrum.

Growing community of inventors

Palos Verdes Estate, CA, United States of America

Slava A Pollack