The Titan Corporation

Ohio Aerospace Institute

Anthony E Smart

John B Abbiss

William V Meyer

Roger P Woodward

Medhat Azzazy

Robert W McCullough

H Michael Cheung

David S Cannell

Roger J Rickey

J Adin Mann, Jr

Thomas W Taylor

James A Lock

Padetha Tin

Jixiang Zhu

An interferometer having a light beam source that produces a plurality of separate and distinct wavelengths of light. Optic fibers are used to transport the wavelengths of light toward an object surface and to allow light reflected from the object to pass through a polarizer to improve the polarization ratio of the reflected light to determine a characteristic of the object surface.

Optical device for measuring a surface characteristic of an object by multi-color interferometry

A method and apparatus for analyzing a fluid containing light scattering components. The apparatus includes a laser adapted to direct abeam of light into the fluid such as a liquid containing particles, and at least two detectors to receive light scattered by the fluid, which received light is used to calculate a physical property of the fluid. A focusing lens may be used to focus the light beam to a focal waist in the fluid to enhance the degree of spatial coherence of the scattered light. The two detectors are aligned onto the focal waist and are adapted to send a signal to a data processor which correlates the signal received from said two detectors. The two detectors are spaced a substantially equal distance from the focal waist and are oriented at substantially the same angle with respect to the direction of propagation of the incident beam. The data processor is adapted to cross-correlate the signals received from the two detectors. A polarizer can be positioned between the focal waist and the two detectors to aid in positioning the detectors and to enhance the efficiency and speed of the measurement.

Cross-correlation method and apparatus for suppressing the effects of

This system measures the speed of an airborne vehicle relative to the surrounding atmosphere. The measurement is based on the scattering of pulses of coherent laser radiation, generated in the vehicle, preferably in the infrared region of the electromagnetic spectrum, by particles naturally present in the atmosphere at all times. The pulses are focused into the atmosphere at a sufficient distance from the vehicle, preferably 10-30 meters, to be beyond that region perturbed by the passage of the vehicle. The frequency of the radiation scattered by the particles differs from the frequency of the transmitted pulses by virtue of the relative motion of the vehicle and the atmosphere. Equipment in the vehicle digitally processes the received energy to determine this frequency difference for each pulse, and hence the component of the vehicle's velocity in the direction of the pulse transmission. Successive pulses are transmitted into the atmosphere in differing directions lying on the surface of a cone whose axis is fixed with respect to the vehicle, making possible the vectorial determination of the vehicle's relative motion. This conical scan is repeated without interruption over successive cycles of pulses. In determining the vehicle's velocity vector from the measured velocity components, account is taken, through weighting factors, of the statistically variable quality of the individual measurements from successive pulses. These weighting factors are derived from the properties of the measurements themselves and are applied to the data to enhance both accuracy and continuity of information.

System for, and method of, determining the speed of an airborne vehicle

A laser package includes a laser with first and second spaced terminals and a layer between the terminals with properties of emitting light when voltage pulses are applied between the terminals. A current of a particular magnitude is produced between the terminals in the time periods between the voltage pulses. The voltage required to produce such current is dependent upon the layer temperature. Variations in this voltage produce variations in the rate of pulses from a thermoelectric cooler included in the laser package. Variations in the rate of such pulses from the thermoelectric cooler affect the rate at which heat is withdrawn by the thermoelectric cooler from the laser. A cooler body is disposed adjacent to the thermoelectric member and is constructed to pass a cooling fluid through the cooler body to cool the thermoelectric member. The cooling fluid passes through an inlet port to a plurality of channels converging at a central recess. This causes the fluid in the recess to be turbulent, thereby increasing the rate at which heat is withdrawn from the central portion of the laser package where the temperature of the laser package is at a maximum. Because the turbulence is greatest only where it must have the highest heat transfer coefficient, the pressure drop, and hence the power necessary to pump the fluid, is minimized. The fluid then flows from the recess through a passageway to an outlet port.

Laser structure including cooling assembly

A source produces light, preferably in a wavelength band of approximately 185-200 nm and in pulses at a suitable frequency (e.g., 100 Hz). The light may be directed in a progressively diverging beam into the atmosphere for a Rayleigh scattering by molecules in the atmosphere in the 185-200 nm wavelength band and for fluorescence by particular molecules (e.g. oxygen) in the atmosphere in another wavelength band (e.g. 210-260 nm). The Rayleigh scattered light and the fluorescent light may pass in a progressively converging beam to two detectors, one responsive to the Rayleigh scattered light to produce first signals and the other responsive to the fluorescent light to produce second signals. Optical elements may prevent the second detector from responding to the fluorescent light and the second detector from responding to the scattered Rayleigh light. A data processor processes the first and second signals to provide outputs representative of the atmospheric pressure and temperature. These outputs may have a great accuracy, in part by regulating the characteristics of the light source and the first and second detectors at times between the successive light pulses from the source. The progressively diverging and progressively converging beams may have a focal point displaced externally of the housing by at least a particular distance to avoid effects of turbulence when the housing is in a moving vehicle.

System for measuring ambient pressure and temperature

A plurality of lasers, each regulated to operate at a particular temperature, are supported by a manifold to direct coherent light into space. The regulation may be provided by producing pulses of a trickle current of a particular magnitude through the laser, measuring the voltage required to produce the trickle current and adjusting the characteristics of a thermoelectric member in accordance with the magnitude of such voltage to adjust the rate at which the thermoelectric member transfers heat from the laser. The lasers produce substantially parallel and thin beams of light in pairs. The light beams in each pair provide an optimum angle for the interception by such paired beams of particles having individual trajectories in space. These particles scatter the light to a receiving lens system disposed within the manifold. The received light then passes through masks which restrict the collected light to a spatial pattern corresponding to the pattern of the light beams from the lasers. The received light beams passing through the masks are detected to produce signals indicative of the light in such beams. The manifold temperature may be regulated to maintain the optical characteristics of the lasers and the receiving system at a constant and optimum value. The regulation may be provided by disposing heat sleeves on the manifold periphery, preferably in both axial and annular directions, and disposing in each heat sleeve a porous wick and a material convertible between liquid and gaseous forms. At positions above the regulated temperature, the liquid vaporizes and travels through the wick toward cooler spots where it vaporizes.

Improvements in a system for determining atmospheric data relating to

Light from a moving airborne vehicle and scattered from atmospheric particles produces at first and second detectors at the vehicle, signals which are spatially and spectrally filtered, and conditioned by amplification and special filtering and converted to digital signals. The digital signals are edited and accepted if they satisfy certain conditions pertaining to a threshold variable with the average amplitude level of the noise plus signals. The digital signals from each particle are grouped. A centroid, based upon a weighting of the signals in each group with amplitude and time, is determined to represent the most probable time at which the particle crossed the peak of the illuminated region. The peak amplitude of each signal from the first detector is paired with the peak amplitude of the successive signals from the second detector. The time difference between the paired signals, and their product amplitudes, are determined. The amplitude products are separated into successive bins on the basis of the time difference between the signals in each pair and are averaged. The bin with the greated average amplitude product and the two (2) adjacent bins are selected. The median time in the bin having the highest average product amplitude is used as a first approximation to the transmit time of a particle. An estimate with enhanced accuracy may be obtained by calculating the 'centroid', by a method analogous to that used above, of a narrow distribution of events selected from those within the three (3) chosen bins.

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Costa Mesa, CA, United States of America

Anthony E Smart