Showing papers on "Apochromat published in 1987"
TL;DR: Using two hyperboloids, this work can control spherical aberration and coma of an imaging x-ray telescope by allowing the coma-free condition at the outer edge and cancelling about half of the defocused image for the largest height of an object by introducing spherical Aberration.
Abstract: Using two hyperboloids, we can control spherical aberration and coma of an imaging x-ray telescope. The coma-free condition is satisfied only at a particular radius of the first mirror. The best performance is obtained when we allow the coma-free condition at the outer edge and cancel about half of the defocused image for the largest height of an object by introducing spherical aberration.
41 citations
TL;DR: In this article, the effect of chromatic aberration on small probes on the basis of wave optics was calculated and an upper limit for chromatic aberrations was established as a practical guide.
15 citations
10 Jun 1987
TL;DR: In this paper, a parametric analysis of f/2, one through four element lenses, relating monochromatic axial performance (spherical aberration) to refractive indices from 1.5 to 2.0 was performed.
Abstract: We have recently completed a parametric analysis of f/2, one through four element lenses, relating monochromatic axial performance (spherical aberration) to refractive indices from 1.5 to 2.0. The literature demonstrates clearly that increasing the number of elements and/or the refractive index causes a reduction of the third-order spherical aberration; in fact the literature shows special cases where the third-order spherical aberration transitions through zero. If we consider an optimum balance for all orders of spherical aberration, we observe a surprising result. One and two element solutions maintain a relatively constant high level of aberration residual for all cases (from 5 - 50 waves peak-to-valley). The three-element solution, however, improves in aberration residual by nearly 6 orders of magnitude from 2 waves peak-to-valley at an index of 1.5 to approximately 0.000005 waves at an index of 2.0. The four-element solution shows a similar, yet not so pronounced, behavior. We will discuss the various solution forms, some of which utilize the aplanatic-concentric principal, and we will show how higher order aberration balancing in the three element case is responsible for the 6 orders of magnitude improvement in performance.
11 citations
TL;DR: In this article, an expression for the longitudinal spherical aberration produced by a spherical refracting surface from parallel incident light in the fifth-order approximation is derived, and a simple experiment to measure the location of focal points formed by nonparaxial rays is also described.
Abstract: An expression for the longitudinal spherical aberration produced by a spherical refracting surface from parallel incident light in the fifth‐order approximation is derived. A simple experiment to measure the location of focal points formed by nonparaxial rays is also described. The results of the measurements are in good agreement with the theory.
3 citations
Patent•
06 Aug 1987
TL;DR: In this paper, an achromatic lens with a corrector for reducing the secondary spectrum and a plane image field is presented. But the free diameter of the crystal lens in the corrector amounting to only 50% of the free diameters of the objective lens, is achieved by the system being constructed from two optical members, one lens of the correctedor consisting of BaF2 or SrF2 and being embedded between glass lenses.
Abstract: The invention relates to an achromatic lens with a corrector for reducing the secondary spectrum and can be used for achieving apochromatic, diffraction-limited correction and a plane image field. The aim of producing an apochromatic system with diffraction-limited representation, 100 mm diameter and 1000 mm focal length, the free diameter of the crystal lens in the corrector amounting to only 50% of the free diameter of the objective lens, is achieved by the system being constructed from two optical members, one lens of the corrector consisting of BaF2 or SrF2 and being embedded between glass lenses.
1 citations