RESUMO
Diffractive wavefront control with spatial light modulator technology has been successfully demonstrated both as a means of steering optical wavefronts and for compensating large optical aberrations. We describe the use of a spatial light modulator operating as a programmable diffractive optic to record extended-field-of-view mosaic images centered about a large off-axis field angle. A gimbaled primary mirror allows the nominal viewing angle to be varied, and diffractive wavefront steering allows images to be acquired at discrete increments in the field angle about the nominal angle. Diffractive wavefront compensation corrects aberrations associated with the primary mirror orientation and changes in field angle introduced by diffractive wavefront steering. A time sequence of images recorded at discrete increments in the field angle is then digitally combined to create a high-pixel-count mosaic image. The effects of diffraction efficiency and wavelength-dependent wavefront errors on image quality are analyzed.
RESUMO
A Fourier analysis treatment of the wavelength dependences associated with modulo lambdar optical path control, treating the general case of a modulo lambdar optical path difference function OPD (x, y) mod lambdar in which the reset wavelength lambdar, is allowed to be an integer multiple of a nominal wavelength lambda0, lambdar=Nlambda0, is presented. Equations are derived describing the wavelength-dependent characteristics of the diffraction efficiency and the wavefront errors associated with all diffracted orders. The results are applied to the cases of diffraction of a planar wavefront and compensation of large aberrations and show that over an extended spectral bandwidth the output field consists of multiple diffracted orders with a range of fractional wavefront errors that diminishes with increasing reset multiple N, but does not reach the diffraction limit associated with conventional optics.
