Diffraction fields very close to the source are shown to have spatial resolution well beyond Rayleigh limits, and other important features. Increased resolution implies higher spatial bandwidths, which is important to optical communication and information processing. THese aspects are reviewed and a metrological application is described.
Two acousto-optic devices are described which, in contrast to the more common Bragg Cell systems which process varying RF inputs by deflecting laser radiation, analyze broad optical spectral inputs using essentially constant RF inputs. The principles described in this paper have been applied to the design and manufacture of a Wide Angle Staring Spectrometer, which is also discussed.
Coherent light, in the presence of aberrations, produces different focal plane effects than does incoherent light. These are examined for primary spherical aberration, coma, tilt, and defocus. Also discussed are two incoherent light systems.
Resolution substantially greater than conventional diffraction limits can be achieved by spacing the diffracting and receiving planes by a few wave lengths. An optical encoder exploiting this fact was successfully manufactured thus highlighting possibilities for other practical systems and devices.