Abstract: The invention provides methods and apparatus for encoding information pertaining to the polarimetric state of transversely propagated radiation—for example, electromagnetic waves—as a modulation of the radiation's frequency power spectrum. In a preferred embodiment, suitable for examining light, the radiation passes consecutively through two birefringent media, each having mutually perpendicular fast and slow axes both perpendicular to the propagation axis. The fast axis of the first medium is rotated with respect the fast axis of the second medium to form an acute angle therebetween. The output of the second birefringent medium comprises a complementary pair of interference fringe systems. The power spectrum of each interference system is modulated in a manner characteristic of the polarization state of the radiation. One of the systems is selected by a linear polarizer. The invention is suitable for use in conjunction with a conventional imaging spectrograph and detector.

Abstract: A portable self-contained power pack is described including a miniature internal combustion motor/alternator combination with an attached fuel supply. The electrical output from the motor/alternator is rectified and controlled to provide a DC output. The DC output is used to charge batteries and/or capacitors. The power pack is designed to be of a weight and size so that it may be carried while in use on the person of the user. The DC output and the batteries and/or capacitors are connected and power personal items. These personal items include, but are not limited to, cell phones, portable radios, laptops, stand alone computers, music and video players and recorders, personal electronic organizers, games and cordless power tools.

Abstract: A miniature, two cycle engine with a linear electrical generator is presented. The piston attaches to the spring and a moving coil is also attached to the spring and/or rod assembly distal from the cylinder head. The spring is formed with an integral end fitting from one piece of preferably titanium stock. A permanent magnet is arranged where the coil moves within the magnet air gap to produce electrical power. The system operates at the resonant frequency of the spring and active mass. A glow plug provides the ignition source and hydrocarbon fuel is used. The package is about an inch wide and about 2-3 inches long, and it weighs about 30 grams.

Abstract: Diagnostic methods for determining an instantaneous rate of pollutant formation in a combustion system are based on measurement of chemiluminescence intensity generated simultaneously with the formation of the pollutant. The chemiluminescent signal is generated by an analog reaction which occurs in parallel with a key step in the formation of a specific pollutant of interest. The connection between the analog reaction and the pollution reaction is such that the chemiluminescent signal indicates the local, instantaneous formation rate of the pollutant of interest.

Abstract: The principle object of the invention is to provide an improved particle analyzer for analyzing particles contained in a gaseous medium. A more specific object is to provide a particle analyzer that provides a measure of the concentration of particles of various sizes in the atmosphere and the make up of the particles of various sizes. A more specific object is to provide an analyzer of the foregoing type which is small inexpensive and suitable for unattended use in the field.

Abstract: An evaporatively cooled rotor for a gas turbine engine. Each rotor defines an internal cavity which includes a vaporization section that corresponds generally to the blade section of the rotor and a condensing section that corresponds generally to the hub section of the rotor. A radial array of circumferentially disposed capture shelves is provided in the vaporization section for capturing cooling fluid contained within the internal cavity and flowing radially outward under the centrifugal field generated during rotation of the rotor. A barrier disposed along the inner surface of the rotor wall in the condensing section slows or temporarily stops the flow of cooling fluid prior to reaching the vaporization section and a perforated baffle attached to the capture shelves prevents cooling fluid from splashing out of the shelves.

Abstract: A cross-road motor vehicle exhaust gas analyzer uses tunable infrared laser differential absorption spectroscopy incorporating photon infrared detection to determine the absolute fractional absorption of a laser by the gaseous medium. Spectroscopic constants of the gaseous species of interest are applied to the absolute fractional absorption to calculate the pertinent absolute column densities. In addition to a laser that sweeps across one or more absorption line of an component of interest, the system of the invention includes a laser source tunable over an absorption line of a reference species; the calculated column density of the reference species is used to normalize the concentration of the component of interest to the fuel consumption rate of the motor vehicle.

Abstract: An evaporatively cooled rotor for a gas turbine engine. Each rotor defines an internal cavity which includes a vaporization section that corresponds generally to the blade section of the rotor and a condensing section that corresponds generally to the hub section of the rotor. A radial array of circumferentially disposed capture shelves is provided in the vaporization section for capturing cooling fluid contained within the internal cavity and flowing radially outward under the centrifugal field generated during rotation of the rotor. A barrier disposed along the inner surface of the rotor wall in the condensing section slows or temporarily stops the flow of cooling fluid prior to reaching the vaporization section and a perforated baffle attached to the capture shelves prevents cooling fluid from splashing out of the shelves.

Abstract: A gas-correlation filter spectroscopy-based method and apparatus for determining the concentration of gas species having significant average broadband absorption incorporates a compensating filter having an absorption spectrum that varies with wavelength similarly to the spectrum of the gas species. The compensating filter eliminates interference due to differential absorption. The invention is especially suited to detecting nitrogen dioxide.

Abstract: A system for measuring and monitoring water vapor concentration in a sample uses as a light source an argon discharge lamp, which inherently emits light with a spectral line that is close to a water vapor absorption line. In a preferred embodiment, the argon line is split by a magnetic field parallel to the direction of light propagation from the lamp into sets of components of downshifted and upshifted frequencies of approximately 1575 Gauss. The downshifted components are centered on a water vapor absorption line and are thus readily absorbed by water vapor in the sample; the upshifted components are moved away from that absorption line and are minimally absorbed. A polarization modulator alternately selects the upshifted components or downshifted components and passes the selected components to the sample. After transmission through the sample, the transmitted intensity of a component of the argon line varies as a result of absorption by the water vapor.

Abstract: A method and apparatus for detecting fluorescence from sunlit plants is based on spectral line discrimination using the A-band and B-band absorption of atmospheric oxygen. Light from a plant including scattered sunlight and the fluorescence from chlorophyll is passed through a chopper into a cell containing low-pressure, high-purity oxygen. A-band or B-band wavelengths present in the light are absorbed by the oxygen in the cell. When the chopper is closed, the absorbed light is remitted as fluorescence into a detector. The intensity of the fluorescence from the oxygen is proportional to the intensity of fluorescence from the plant.

Abstract: Heterogeneous fuel compositions suitable for use in hybrid rocket engines and solid-fuel ramjet engines, The compositions include mixtures of a continuous phase, which forms a solid matrix, and a dispersed phase permanently distributed therein. The dispersed phase or the matrix vaporizes (or melts) and disperses into the gas flow much more rapidly than the other, creating depressions, voids and bumps within and on the surface of the remaining bulk material that continuously roughen its surface, This effect substantially enhances heat transfer from the combusting gas flow to the fuel surface, producing a correspondingly high burning rate, The dispersed phase may include solid particles, entrained liquid droplets, or gas-phase voids having dimensions roughly similar to the displacement scale height of the gas-flow boundary layer generated during combustion.

Abstract: An off-axis cavity absorption cell (10) includes astigmatic mirrors (22, 28). The cell design is based on a prototype design that yields a closed beam path having a desired geometry, but the mirrors are fabricated so that the ratios of their radii of curvature are actually larger than those calculated for the prototype. To achieve the desired closed beam path, the mirror spacing is adjusted from that of the prototype design, and the planes of their axes of greatest curvature are oriented out of the alignment that characterizes the prototype design. If the mirrors' manufacturing process yields errors in the curvature-radius ratios within certain prescribed limits, a cell of this design can be adjusted to achieve the closed beam path by simply changing the mirror separation and the "twist angle" between their respective planes of maximum curvature radius.

Abstract: Disclosed herein is a process for producing a thin film of epitaxial material on a substrate surface at low temperatures under ultrahigh vacuum conditions. In general, precursor compounds are deposited, and converted into the epitaxial material, on the substrate surface at a temperature at which they undergo no substantial dissociation. By way of example, a beam-deposited admixture of dimethyl tellurium and dimethyl cadmium is efficiently converted to an epitaxial cadmium telluride crystal on the surface of a GaAs(100) substrate placed in an ultrahigh vacuum chamber by low power, 193 nm laser irradiation (pulse fluence approximately 6 mJ cm.sup.-2) at substrate temperature of -150.degree. C. and by subsequent annealing at 200.degree. C. for 30 seconds. In addition to efficient use of precursors, this process also permits considerable improvement of pattern resolution.

Abstract: In a laser emitter-receiver system, a tunable diode laser provides a beam of coherent light having a selected frequency. An infrared detector spaced from the source detects the light transmitted along the beam path between the source and the detector and produces a corresponding output in response thereto. A heating laser provides radiation to the diode laser to heat, and thereby to change the frequency of, the latter laser. The radiation from the heating laser is varied periodically to modulate the intensity of the radiation incident on the diode laser thereby to frequency-modulate the diode laser output over a selected tuning range. A controller responsive to the detector output regulates the current to the diode laser to minimize selected frequency components of the modulated light beam from that laser so that the power output of the diode laser varies minimally when that laser is tuned over the selected tuning range.

Abstract: A micro graphic representation such as a hologram is formed by directing from a computer to a display surface signals to form a very small portion of the graphic representation of the display surface, focusing a micro image of the display on a recording element, mechanically moving the recording element to a new position, optically measuring the new position and signalling the computer the precise new position and then sending to the display surface next signals to form on the display surface a next very small portion of the graphic representation with the position of the next portion modified to compensate for the difference between the measured position and the required position. The piece-by-piece display is repeated a large number of times to record an entire graphic representation. One embodiment of the invention is a hologram writer.

Abstract: A hologram is written from x, y, z data by presenting an information beam at a holographic medium with x and y coordinates represented by x and y position on the medium and z coordinates represented by distance between the holographic medium and a point position of the beam close to the medium, while simultaneously presenting a reference beam in interference with the information beam and of a size comparable with the size of the information beam at the holographic medium. The area of the information beam and the reference beam at any position on the holographic medium is a small fraction of the total area of the hologram.

Abstract: Coherent light such as a laser beam is spatially modulated by causing it to interact at a photosensitive material such as a crystal with a focussed image of non-coherent light. An electric potential is applied to the crystal either transversely to the direction of the light or in line with the direction of the light according to either the Kerr effect or the Pockels effect. Typical crystals include Bismuth-silicon-oxide and strontium-barium-niobate.

Abstract: Image enhancement is achieved to increase the ability to distinguish details otherwise difficult to discern in bright and dark areas of a photorecord by reflecting light off surface perturbations on the record and displaying the reflected light by means of schlieren optics.

Abstract: Methods and apparatus are disclosed for studying motion of an object or element, to determine not only quantities of motion but also direction of motion. A laser beam or the like is circularly polarized and directed to two or more retroreflectors and then to a detector. Beams of different frequencies are established and determination of relative direction of motion of the retroreflectors is made from the increase or decrease of frequency of beats of one beam against the other. In one embodiment, left and right circularly polarized light is reflected, and one of the beams is frequency-shifted. The light, being circularly polarized, is insensitive to rotational orientation of the test object, while maintaining directional and motion information.