The United States of America As Represented by the Administrator of the

Other

United States of America As Represented by the Administrator of Nasa

Michael J Kavaya

Grady J Koch

Jeffrey Y Beyon

Robert A Frosch

Farzin Amzajerdian

James R Magee

Sammy W Henderson

Paul J Suni

Robert T Menzies

R Milton Huffaker

Charley P Hale

Systems, methods, and devices of the present invention enable post processing of airborne Doppler wind LIDAR data. In an embodiment, airborne Doppler wind LIDAR data software written in LabVIEW may be provided and may run two versions of different airborne wind profiling algorithms. A first algorithm may be the Airborne Wind Profiling Algorithm for Doppler Wind LIDAR ('APOLO') using airborne wind LIDAR data from two orthogonal directions to estimate wind parameters, and a second algorithm may be a five direction based method using pseudo inverse functions to estimate wind parameters. The various embodiments may enable wind profiles to be compared using different algorithms, may enable wind profile data for long haul color displays to be generated, may display long haul color displays, and/or may enable archiving of data at user-selectable altitudes over a long observation period for data distribution and population.

Airborne doppler wind lidar post data processing software DAPS-LV

Systems, methods, and devices of the present invention enable airborne Doppler Wind LIDAR system measurements and INS/GPS measurements to be combined to estimate wind parameters and compensate for instrument misalignment. In a further embodiment, the wind speed and wind direction may be computed based on two orthogonal line-of-sight LIDAR returns.

Airborne wind profiling algorithm for Doppler Wind LIDAR

A lidar remote sensing system wherein a laser signal is transmitted along an optical path through a telescope having a primary and secondary mirrors and a rotating prism at the telescope output. When the reflected signal from the target is received it is passed back through the system to a detector, where it is heterodyned with a signal from a local oscillator to detect Doppler frequency shifts in the returned signal. Since the prism is rotating, the prism will be at one position when the signal is transmitted and at another when the returned signal is received. This causes the reflected signal to be off the optical path, reducing the power of the returned signal. To correct this problem a de-rotator or prism is mounted for rotation, in synchronism with the rotating prism, about the optical path in a position to intersect the returned beam and refract it back onto the optical path to reduce the power loss in the returned signal.

Lidar remote sensing system

A coherent laser radar system operating at an eyesafe wavelength above 1.4 microns has been provided for measurement of the position and velocity of hard targets and aerosol targets, said system comprising a frequency-stable master laser and an injection-seeded Q-switched slave laser for generating signals for transmission to the target. Means for obtaining highly accurate velocity and range measurements are provided. Data from signal transmissions and receptions taken over a range of angles are analyzed to map target positions and velocities in time and space.

Eyesafe coherent laser radar for velocity and position measurements

A method and apparatus for testing the operation of a complex stabilization circuit in a closed-loop system (12, 38) is comprised of a programmed analog (60-72) or digital (80-86) computing system for implementing the transfer function of a load (12), thereby providing a predictable load. The digital computing system employs a table stored in a microprocessor (84) in which precomputed values of the load transfer function are stored for values of input signal from the stabilization circuit (38) over the range of interest. This technique may be used not only for isolating faults in the stabilization circuit (38), but also for analyzing a fault in a faulty load by so varying parameters of the computing system as to simulate operation of the actual load with the fault.

Method and apparatus for transfer function simulator for testing complex

Continuous offset tuning of a frequency stabilized cw gas laser (10) is achieved by using a spectrophone (14) filled with the same gas as the laser for sensing a dither modulation, detecting a first or second derivative of the spectrophone output with a lock-in amplifier (28), the detected output of which is integrated (36), and applying the integrator output as a correction signal through a circuit (24) which adds to the dither signal from an oscillator (22) a dc offset (B1) that is adjusted with a potentiometer (26) to a frequency offset from the absorption line center of the gas, but within the spectral linewidth of the gas. Tuning about that offset frequency is achieved by adding a dc value (B2) to the detected output of the dither modulation before integration using a potentiometer (30). Tuning may also be achieved by changing the amplitude of dither modulation, or changing the pressure of the spectrophone gas, or any combination of these three tuning parameters which affect the amount of offset of the stabilized frequency from line center.

Spectrophone stabilized laser with line center offset frequency control

A Stark effect spectrophone is provided using a pulsed or continuous wave laser (33) having a beam with one or more absorption lines of a constituent of an unknown gas. The laser beam is directed through windows (31,032) of a closed cell (30) while the unknown gas to be monitored is caused to flow continuously through the cell between electric field plates (34, 35) disposed in the cell on opposite sides of the beam path through the cell. The plates are so disposed as to be divergent, e.g., flat plates at an oblique angle relative to each other, or plates shaped according to a mathematical function so that, with constant voltage applied across the plates, there is a linear variation in electric field strength along the beam path. Discrete pressure transducers (37) are positioned at field strength points of interest. When the beam is pulsed, energy absorbed by the gas then present in the cell will increase at each point along the beam path according to the spectral lines of the constituents of the gas for the particular field strengths at those points. The pressure measurement at each point during each pulse of energy will yield a plot of absorption as a function of electric field for simultaneous detection of the gas constituents of interest. Signal averagers (39) are provided to permit repeatedly pulsing the laser for averaging before recording and processing the data. When the beam is continuous (i.e., not pulsed), the bias voltage may be modulated to dither the electric field at each point. Still other techniques that may be used for modulation of the absorbed energy include polarization rotation, wavelength modulation and conventional 50% duty cycle chopping of the incident beam.

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San Gabriel, CA, United States of America

Michael J Kavaya