Clark-mxr, Inc.

General Dynamics Advanced Information Systems, Inc.

Other

Edward F Gabl

William G Clark

Ron S Goodman

Mark A Ricoy

Scott D Connell

Elizabeth T Batteh

Yang Pang

David R Walker

Philippe Bado

Provided are two-dimensional autofocus methods in a synthetic aperture radar (SAR) system which include: (1) two-dimensional pulse pair product algorithm including shear PGA, eigenvector phase history ('EPH'), shear PGA/EPH); (2) two-dimensional optimization algorithms including parametric one-dimensional estimate/two-dimensional correction, parametric two dimensional estimate/two-dimensional correction, unconstrained two-dimensional nonparametric and constrained two-dimensional nonparametric methods; (3) a two-dimensional geometry filter algorithm; (4) a two-dimensional prominent point processing algorithm; (5) a one-dimensional phase estimate of higher order two dimensional phase errors; and, (6) a fast SHARP parametric autofocus algorithm.

Methods for two-dimensional autofocus in high resolution radar systems

An apparatus for maintaining an electromagnetic beam, namely a laser beam, aimed at a particular point in space and aligned with a unique propagation path. The apparatus includes one or more adjustable beam steerers located in the propagation path, and first and second spaced apart beam position detectors arranged in the beam path. The beam steerer(s) are preferably adjustable along at least two orthogonal axes of rotation for controlling the propagation direction of the beam. Error signals from the position sensors are fed into a beam steerer controller connected to the beam steerer(s) for electro-mechanically adjusting the beam steerer. The method of the invention involves fixing the propagation path on an angularly adjustable beam steering surface so that the propagation path at a different unique point in space, such as a target, can be controlled by adjusting the angular orientation of that beam steerer.

Apparatus for controlling the position and direction of a laser beam

A regenerative amplifier includes a resonant cavity having a gain medium and a spectral filter located in the cavity. A source is provided to pump the gain medium and thereby raise it to an excited state. Elements are also provided for creating laser seed pulses which are then injected into the resonant cavity, these elements preferably include in part a mode-locked oscillator having a wavelength substantially the same as that at which the gain medium can support amplification of the energy of the injected pulse. In a preferred embodiment the gain medium is Ti:Sapphire for both the amplifier and oscillator. Also, in the preferred embodiment the seed pulse from the oscillator is stretched in time by multiplicative factors sufficient to ensure that upon amplification, the seed pulse power density remains below the self-focusing threshold of the material through which the pulse is passed. The seed laser pulses are injected into the resonant cavity of the regenerative amplifier so as to provide multiple traversals of the resonant cavity and the gain medium therein, thereby amplifying the pulses. The pulse is recompressed back to some predetermined pulse width of interest to the user; for example, back to the temporal pulse width that is limited by the spectral bandwidth of the output pulse.

Regenerative amplifier incorporating a spectral filter within the

A regenerative amplifier includes a resonant cavity having a gain medium and a spectral filter located in the cavity. A source is provided to pump the gain medium and thereby-raise it to an excited state. Elements are also provided for creating laser seed pulses which are then injected into the resonant cavity, these elements preferably include in part a mode-locked oscillator having a wavelength substantially the same as that at which the gain medium can support amplification of the energy of the injected pulse. In a preferred embodiment the gain medium is Ti:Sapphire for both the amplifier and oscillator. Also, in the preferred embodiment the seed pulse from the oscillator is stretched in time by multiplicative factors sufficient to ensure that upon amplification, the seed pulse power density remains below the self-focusing threshold of the material through which the pulse is passed. The seed laser pulses are injected into the resonant cavity of the regenerative amplifier so as to provide multiple traversals of the resonant cavity and the gain medium therein, thereby amplifying the pulses. The pulse is recompressed back to some predetermined pulse width of interest to the user; for example, back to the temporal pulse width that is limited by the spectral bandwidth of the output pulse.

In a pump/probe experiment, information about an event is detected and correlated with an accumulatable quantity representing the elapsed time interval between the arrival of the pump and probe pulses at the experiment. The accumulatable quantity is used to configure the pump and probe sources to eliminate temporal resolution problems caused by pulse timing jitter, the complexity of amplification, continuum generation, and subsequent reamplification, as well as data acquisition rate limitations. Two pulse sources serve as pump and probe pulses respectively. Each pulse is directed at the experiment. A portion of each pump pulse is diverted to a detector before it reaches the experiment, and a portion of each probe pulse is diverted to another detector. The pump and probe pulses are no-coincident in time at the experiment. Quantities related to the time difference and the information imposed on the probe pulse by the experiment are accumulated to obtain data about the temporal evolution of the event.

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Saline, MI, United States of America

Edward F Gabl