Multi-laser coherent imaging through aberrating media
AssigneeHughes Aircraft Company
InventorDouglas E. Elerath
Life of this patent
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Abstract
An improved method for imaging laser illuminated objects through a near field aberrator, and/or for measuring the phase distortions of the aberrator. The method utilizes a set of at least three laser beams that are offset with respect to each other in a lateral direction. This offset produces three similarly offset but otherwise identical complex fields in the wave fronts of the reflected return at the sensors. The individual laser beams are tagged with identifying characteristics that are apparent at the sensors, whereby the reflected return may be identified and classified according to origin in individual laser beams. The sensor signals are processed to measure distortions in the aberrator and to apply the measurements to obtain an enhanced image.
Claims19
A method of determining phase distortions induced by a near field aberrator in an active laser system, said method comprising the steps of:
- forming a plurality of laser beams having known characteristic signals, and pointing the laser beams at a common object that generate laser return signals from illuminated target objects;
- maintaining spatial displacement of the laser beams with respect to each other in an orthogonal coordinate system including the axis of one reference laser beam;
- incorporating a distinguishable identification signature signal imbedded in the characteristic signal of each laser beam;
- using an array of detectors responsive to the laser characteristic signals to provide detector output signals representing return signals from the target objects, wherein center to center spacings between individual detectors is substantially equal to the spatial displacement of the axes of the laser beams times the ratio of a return path range divided by a transmit path range;
- extracting the laser return signals according to their identification signature signal from each detector output signal and classifying each return signal according to it's origin among the plurality of laser beams;
- and
- comparing the return signals from each detector respecting each laser beam thereby determining the aberrator induced phase distortion.
An optical imaging system for imaging laser-illuminated objects through an aberrating medium, said system comprising:
- platform means for illuminating an object, said platform means including laser means for pointing a plurality of laser beams at the object, said beams being spatially displaced with respect to each other in an orthogonal coordinate system;
- and tagging means for embedding identifying components in the laser beams;
- and
- a plurality of detectors adapted to receive the laser beams reflected by the object, said detectors being arranged in a two-dimensional array having a center-to-center detector spacing substantially equal to the spatial displacement of the laser beams or to fractions of the spatial displacements.
Dependencies are inferred from the claim text.