rus
Issue #4/2026
A. V. Ustinov, O. A. Dyukareva, S. N. Khonina
Focusing Specifications with a Small Pupil Size
Focusing Specifications with a Small Pupil Size
DOI: 10.22184/1993-7296.FRos.2026.20.4.272.282
The influence of diffraction at a circular aperture is investigated in the analysis of nonparaxial focusing by parabolic and ideal lenses at small pupil sizes. The performance of such focusing elements is illustrated using a nonparaxial diffraction model based on the Rayleigh-Sommerfeld integral. The analytical and numerical results demonstrate that nonparaxial effects and the differences in the behavior of two lenses depend not only on the numerical aperture of the optical element (the ratio of its radius to focal length) but also on the pupil size. When the aperture approaches a “pinhole”, i. e., its radius is only a few wavelengths, the combined effect of the lens and the pupil must be considered.
Subscribe to the journal Photonics Russia to read the full article.
The influence of diffraction at a circular aperture is investigated in the analysis of nonparaxial focusing by parabolic and ideal lenses at small pupil sizes. The performance of such focusing elements is illustrated using a nonparaxial diffraction model based on the Rayleigh-Sommerfeld integral. The analytical and numerical results demonstrate that nonparaxial effects and the differences in the behavior of two lenses depend not only on the numerical aperture of the optical element (the ratio of its radius to focal length) but also on the pupil size. When the aperture approaches a “pinhole”, i. e., its radius is only a few wavelengths, the combined effect of the lens and the pupil must be considered.
Subscribe to the journal Photonics Russia to read the full article.
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