Forming of an image of an extended absolutely absorbing slit hole with arbitrary opening in coherent light

Abstract

The features of forming an image of extended absolutely absorbing objects of constant thickness with arbitrary opening of holes have been studied in a coherent-optical system. On the base of the constructive approximation of the spectra of spatial frequencies (Fraunhofer difractional patterns) of objects with different dimensions relations front ( D ) and back ( D ) apertures, formulas for the field in the image of the front face were obtained and analyzed. Cases of objects with a noticeably expanding (bevel and noticeably narrowing apertures of an extended hole have been investigated in detail. It was found that in the case of large bevels, the structure of the image of the front face depends on the bevel sign (opening). With a positive reveal, when the back face is in the shadow region, the field at the output of the system corresponds to the image of the front face, and with a negative one, the image of the back face is observed. It is shown that error of determination of boundaries in image of active face of object is inversely proportional to square of its bevel. The invariant properties of the projection system for forming images of external faces of extended objects with large positive and negative bevels are analyzed.