Abstract:

In optical processors the structure (objector filter) can be considered as a superposition of Fourier components, that is of sinusoidal gratings of different spatial frequencies and orientations. If these gratings do not work in parallel light, aberrations will appear. The fourth-order aberration function introduced by each of the gratings depends on the diffraction or field angle. Taking into account the grating equation and if the wavelength and interference order are fixed, the field angle is associated with the spatial frequency of the grating. When a plane structure with its normal coincident with the optical axis of the lens system is considered, the Seidel aberrations at a given point of the spectral plane are that of a grating which has the spatial frequency that corresponds to that point. The expressions for the aberrations introduced by the structure are totally similar to those obtained for centred optical systems and can be incorporated into the Seidel sums for application to the usual method of predesign. © 1994 Taylor and Francis Ltd.