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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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Proceedings ArticleDOI
10 Apr 1996
TL;DR: In this paper, an apochromatic 40X/1.2 NA indirect water-immersion objective with adjustable corrector for coverslip thickness was used for high-resolution microscopy.
Abstract: Living cells and other non-embedded biological specimens present a challenge in high- resolution microscopy because of their relatively low refractive index. It is well known that when oil-immersion objectives are used to look into these specimens, spherical aberration resulting from the index mismatch causes axial as well as transverse broadening of the 3D point spread function. Both effects reduce 3D resolution significantly, and cause the microscope to be axially shift-variant, thus complicating 3D deconvolution-based computational refinement. Axial shift variance should be much less a problem when water immersion objectives are used. With the aim of improving image data and our ability to refine it computationally, we have evaluated an apochromatic 40X/1.2 NA indirect water- immersion objective having an adjustable corrector for coverslip thickness. This work involves comparison of measured and computed 3D point spread functions, and comparison to the data acquired with an oil-immersion lens system. We show that focus-dependent spherical aberration is greatly reduced in the water-immersion system.© (1996) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

5 citations

Journal ArticleDOI
TL;DR: In this paper, the authors present the results of a series of calculations on the distribution of light near the star focus of a centered lens system in the following cases: Freedom from aberration.
Abstract: The paper presents the results of a series of calculations on the distribution of light near the star focus of a centered lens system in the following cases: Freedom from aberration. Primary spherical aberration. Zonal spherical aberration. In the two latter cases the condition chosen is that when the least residual phase differences amount to π/2. The characteristic extra-focal effects are determined, and the effect of primary spherical aberration on resolving power is discussed. In the case of zonal aberration the greatest axial intensity is not found at the focus giving least phase residuals. In both cases of aberration a concentration closely resembling in some respects the Airy disc characteristic of zero aberration is found. These results are an extension of those previously obtained by Conrady and Buxton.

5 citations

Journal ArticleDOI
TL;DR: Compensation of diffraction-induced angular dispersion of ultrashort pulses up to a second order is reported on and a strategy for chromatic correction profits from high Dispersion of kinoform-type zone plates is proposed.
Abstract: We report on compensation of diffraction-induced angular dispersion of ultrashort pulses up to a second order. A strategy for chromatic correction profits from high dispersion of kinoform-type zone plates. Ultraflat dispersion curves rely on a saddle point that may be tuned at a prescribed wavelength. Validity of our approach may reach the few-cycles regime.

5 citations

Patent
30 Apr 2015
TL;DR: In this paper, an optical element manipulates the modulation transfer function assigned to the first and second images to extend the depth of field to rectify the problem of out-of-focus blur for infrared radiation.
Abstract: A lens unit (120) shows longitudinal chromatic aberration and focuses an imaged scene into a first image for the infrared range in a first focal plane and into a second image for the visible range in a second focal plane. An optical element (150) manipulates the modulation transfer function assigned to the first and second images to extend the depth of field. An image processing unit (200) may amplify a modulation transfer function contrast in the first and second images. A focal shift between the focal planes may be compensated for. While in conventional approaches for RGBIR sensors contemporaneously providing both a conventional and an infrared image of the same scene the infrared image is severely out of focus, the present approach provides extended depth of field imaging to rectify the problem of out-of-focus blur for infrared radiation. An imaging system can be realized without any apochromatic lens.

5 citations


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Performance
Metrics
No. of papers in the topic in previous years
YearPapers
20214
20204
20196
20188
201716
201625