Laser speckle imaging
OwnerDavid L. Friedinventor
Life of this patent
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Abstract
Satellite imaging through a turbulent atmosphere is provided at better than turbulence-limited resolution using laser speckle statistics on reflections of orthogonal spatially periodic illumination patterns. The second harmonic of a covariance function of phase provides the phase difference between nearby spatial frequencies. By summing such phase differences over many spatial frequencies a spectral phase distribution of an image can be obtained. A spectral intensity distribution can be obtained using laser speckle statistic during uniform illumination of the target. The combined intensity and phase spectral distributions can be inverse Fourier transformed to obtain the desired image.
Claims10
A system comprising:
- detector means for determining at least one spatial frequency component of an incident laser speckle distribution, said detector means including at least a first detector and a second detector;
- scanning means for scanning a target with a first laser illumination pattern with a spatially periodic component in a first direction so as to produce reflections which in turn yield laser speckle distributions at said detector means;
- and
- statistical means for determining the phase difference between at least two spatial frequency components of the image of said target from a series of distributions determined by said detector means.
A method comprising:
- scanning a target with a laser illumination pattern including a first spatially periodic component;
- detecting at least one spatial frequency component of laser speckle distributions of the reflection of said laser illumination pattern by said target using at least a first pair of spaced detectors so that plural detections are made for each of multiple phases of said pattern relative to said target;
- and
- from the detections, statistically determining the phase difference between two spatial frequencies.
Dependencies are inferred from the claim text.