Line-spread function relatively insensitive to defocus

Abstract

A new approach for obtaining line-spread functions (LSF's), which vary slowly in out-of-focus planes, is described. Based on this approach, we report a LSF that shows relatively less sensitivity to focus errors than that shown by both the diffraction-limited LSF and a LSF previously reported.

Tunable Gaussian mask for extending the depth of field

“…1 and 2 in Eq 3, we obtain . (4) It is apparent from Eq. 4 that inside the pupil aperture, the overall amplitude transmittance varies as a Gaussian function.…”

“…Certain amplitude masks and some phase filters are useful for producing out-of-focus MTFs that do not have zeros inside their passband [3][4][5][6][7][8][9][10][11][12][13][14][15][16]. However, the out-offocus MTFs exhibit undesired oscillations around a tendency line.…”

Imaging characteristics of a birefringent lens with primary spherical aberration under broadband illumination

“…The use of semitransparent and phase annuli to enhance the resolving power as well as focal depth of optical instruments was suggested by Taylor et al 3 Tsujiuchi 4 and Asakura et al [5][6][7] pointed out that an appropriate modification of the pupil function of the optical systems may also lead to a suppression of the residual aberrations inherent in the unmasked pupil. The use of spatial filters for achieving a high focal depth as well as for simultaneous reduction of the effects of spherical aberration as reported by Castaneda et al [8][9][10][11] needs special mention. Recently, Mezouari et al 12 employed phase filters for reduction of defocus and spherical aberrations.…”

New apodizers that arbitrarily decrease sensitivity to defocusing or to the variation of spherical aberration

“…1-3. In particular, apodizers likely to reduce a system's sensitivity to focusing errors have received considerable attention (4)(5)(6)(7)(8)(9)(10). In the search for the optimum in such apodizers, a major advance has been made recently by OjedaCastafieda and Berriel-Valdos.…”