Topic
Apochromat
About: Apochromat is a research topic. Over the lifetime, 642 publications have been published within this topic receiving 7934 citations.
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TL;DR: The chromatic field aberration of the magnetic lens in the electron microscope is theoretically studied in this paper, where the coefficients of chromatic difference in rotation and magnification of all the lenses are calculated.
Abstract: The chromatic field aberration of the magnetic lens in the electron microscope is theoretically studied.Good results are obtained for the coefficient of the chromatic difference in magnification of the objective, taking into account the inclination of the principal illuminating rays. The same coefficient of the intermediate lens increases rapidly as the magnification is reduced by the intermediate lens. The calculated results agree well with experimental results.Calculated results are given for the coefficients of chromatic difference in rotation of all lenses as well as for the coefficient of chromatic difference in magnification of the projection lens.
5 citations
Patent•
14 Nov 2011TL;DR: In this article, the authors introduce higher order aberrations, e.g., spherical aberration (SA) for different sub-optical zone diameters, for intraocular lenses.
Abstract: An intraocular lens introduces higher order aberrations, e.g., spherical aberration (SA), for different sub-optical zone diameters. For example, a lens may have a central sub-optical zone which introduces a spherical aberration. Alternatively, a full optical zone design can be used combining defocus with a higher-order aberration.
5 citations
23 Nov 2011
TL;DR: In this article, a catadioptric achromatic optical system consisting of a reflecting mirror and a couple of air-spaced negative doublets is designed by using normal glasses based on PWC method to get a completely secondary spectrum removed and cramped construction telescopic optical system.
Abstract: According to technical requirements,an apochromatic telescopic optical system which is characterized by the focal length
1.5m~2m,with the visible region spectrum band is needed.The successful design consists in using normal glasses based
on PWC method to get a completely secondary-spectrum-removed and cramped construction telescopic optical system in
this paper.Firstly, by the aberration theory and ZEMAX optical design software,a catadioptric achromatic optical system
composed of a reflecting mirror and a couple of air-spaced negative doublets are designed.The initial configuration of
optical system is calculated by PWC method and the proper couple of air-spaced negative doublets are chosen by the
theory of achromatic.By comparing with various optical systems with different couple of air-spaced negative doublets, it
is found that the combination of the heavy crown glass ZK7 and heavy flint glass ZF3 is effective to correct chromatic
aberration and its secondary spectrum value is minimality.It can conclude that fact with the abbe number of ZK7 is twice
than ZF3 make the good result and give guiding to the design of the same type of optical system. Secondary,according to
the theory of secondary spectrum,the secondary spectrum value to be corrected is analyzed and the compensation can be
changed by adjust the magnification power.The comparison is presented and the final telescopic optical system with
cramped construction is achieved, and the goal of apochromatism and other aberration is reached.
5 citations
TL;DR: In this article, the secondary spectrum in a two-component system made from glasses with ordinary dispersion behavior can be eliminated by computer modeling, and the necessary conditions for this are an air gap between the components that is commensurable with the focal length of the system and large longitudinal chromatism of the second component.
Abstract: This paper shows that the secondary spectrum in a two-component system made from glasses with ordinary dispersion behavior can be eliminated by computer modelling. The necessary conditions for this are an air gap between the components that is commensurable with the focal length of the system and large longitudinal chromatism of the second component. Optical layouts are given, along with the aberrations of apochromatic objectives consisting of glasses with ordinary dispersion behavior.
5 citations
TL;DR: Modulation transfer functions (MTFs) were generated using a model that included polychromatic defocus and indicated that image quality was usually best when IOLs allowed overall ocular spherical aberration that was slightly positive, rather than strongly positive, zero, or negative.
Abstract: Polychromatic defocus could affect the optimal residual spherical aberration that could yield the best image quality for patients with intraocular lenses (IOLs). Modulation transfer functions (MTFs) were generated using a model that included polychromatic defocus. The maximum MTF volume occurred at + 0.05 μm of overall ocular spherical aberration. For 3 case studies, the optimal overall ocular spherical aberration was ~0.05 μm more positive with the contribution of polychromatic defocus than without it. Overall, the model indicated that image quality was usually best when IOLs allowed overall ocular spherical aberration that was slightly positive, rather than strongly positive, zero, or negative.
5 citations