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A description is given of the design, operation, and test over a 2-km path (roundtrip) of a continuous wave, coherent laser array receiver that uses two independent aperture-receivers whose intermediate frequencies are electro-optically co-phased in real time and then added as a proposed way to overcome effective aperture limitations imposed by atmospheric turbulence and to mitigate signal fading associated with atmospheric turbulence and speckle effects. The experiment resulted in a mean carrier-to-noise ratio increase of 1.8, which is within 1% of the theoretical predictions, when the two signals were phase locked, versus no increase without phase locking. Further, the carrier fading strength, or normalized carrier-to-noise ratio variance, was reduced by a factor of 0.53, which is within 2% of the theoretical prediction. The bandwidth of the electro-optic phase-locked loop was measured to be of the order of 600 Hz, which is adequate to compensate for atmospheric refractive turbulence fluctuations.

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One-dimensional sections of digital images with space-variant blurs from an uncorrected optical system are restored using Wiener filtering and the Richardson-Lucy method. The simulated blur is from a single-lens optical system configured at moderate focal-length-to-aperture ratio (f#) and near-infinite conjugate. The sections are taken over a range of field-angle displacements from on-axis to approximately 15-deg off-axis. The results identify a range of field angles over which Wiener filtering is useful for sectioned restoration of blurred images from an optical system with significant point-spread-function space-variance. The results also establish a field angle range over which an iterative restoration method such as Richardson-Lucy would be necessary to accommodate point-spreadfunction space-variance.