  Synthetic aperture radar (SAR) can measure the phase with antenna and
microwave, which cannot be directly extended to visible light imaging due to
phase lost. In this letter, we reported an active remote sensing with visible
light via reflective Fourier ptychography (FP), termed coherent synthetic
aperture imaging (CSAI), achieving high resolution, wide field-of-view (FOV)
and phase recovery. A proof-of-concept experiment was reported with laser
scanning and a collimator for the infinite object. Both smooth and rough
objects are tested, and the spatial resolution increased from 15.6 um to 3.48
um with a factor of 4.5. The speckle noise can be suppressed by FP
unexpectedly. Meanwhile, the CSAI method may replace the adaptive optics to
tackle the aberration induced from atmospheric turbulence and optical system by
one-step deconvolution.
