Abstract: A novel optical fiber structure is described which includes an end thereof for transmitting optical signals and substantially reducing reflections of optical signals thereat wherein the fiber end has a substantially flat end surface disposed at an angle to a plane perpendicular to the transmission axis of the fiber equal to or greater than sin.sup.-1 (NA/n) where NA is the numerical aperture and n is the index of refraction of the fiber core material, and the fiber outer surface has adjacent the end surface a flattened portion of preselected depth and length whereby substantially all paraxial and meridional optical signals propagated along the fiber axis are transmitted through the end surface and skew rays transmitted along the fiber are substantially attenuated near the fiber end.

Abstract: A time-shared aperture device using the laser illuminated target to provide a return wavefront which passes through the optical train and beam expander. The distortions in this return wavefront are sampled by a rotating beam chopper which completely blocks the outgoing beam, thereby preventing scattered laser light in the optical train and beam expander from drowning out the fainter target return. Wavefront analyzers provide an indication of errors present in the optical system so that correction may be applied.