SHEARED-BEAM IMAGING - AN EVALUATION OF ITS OPTICAL COMPENSATION OF THICK ATMOSPHERIC-TURBULENCE

Sheared-beam imaging (SBI) should compensate the effects of an idealiz ed layer of turbulence located either in a transmitter/detector plane or in an object plane. This motivated the study of optical compensatio n of SBI in the presence of uniformly distributed turbulence over long horizontal paths in the cases of ideally smooth and ideally rough ext ended objects. The phase error along a one-dimensional wave front resu lting from SBI observation is computed numerically in the long-path re gime and is compared with that of an equivalent conventional system fo r the case of a large smooth object. It is found that for the conditio ns considered the phase errors of the SBI system are greater than thos e of a conventional system. In the case of an ideally rough object the extra information furnished by the SBI observations does not lead to data that can be inverted to compute an image by the conventional shea ring-interferometric algorithm. The phase errors in imaging a point re flector, however, are perfectly compensated.