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Light Microscopy
Published in Thomas A. Barber, Control of Particulate Matter Contamination in Healthcare Manufacturing, 1999
Objectives are divided into types according to how they are corrected for the various aberrations. There are achromats, semiachromats or fluorites, and apochromats. In achromatic lenses, chromatic aberrations are generally corrected for two colors, and spherical aberration is corrected for one color. Semiapochromatic lenses incorporate correction for both defects in two colors. Apochromats are corrected for chromatic aberrations in three colors and spherical aberration in two.
Confocal Microscopy
Published in Guy Cox, Fundamentals of Fluorescence Imaging, 2019
Simple lenses bring different colors to different focal points since glass naturally has different refractive indices to different wavelengths. Achromatic lenses have a straightforward correction which brings two wavelengths, typically red and blue, to the same focus. Other wavelengths will not be too far out but in confocal microscopy we need precision—excitation and fluorescence must come to the same focus.
Chromatic Aberrations
Published in Daniel Malacara-Hernández, Zacarías Malacara-Hernández, Handbook of OPTICAL DESIGN, 2017
Daniel Malacara-Hernández, Zacarías Malacara-Hernández
The effective focal length and the back focal length are equal in a thin lens. Thus, in a thin achromatic lens, both the axial achromatic and the magnification chromatic aberrations are corrected. Another interesting conclusion is that a system of two separated lenses has both chromatic aberrations corrected only if the two components are individually corrected for axial chromatic aberration.
Design of an interference system for measuring the transverse beam size in HLS-II
Published in International Journal of Optomechatronics, 2022
Sanshuang Jin, Yunkun Zhao, Baogen Sun, Leilei Tang, Fangfang Wu, Tianyu Zhou, Ping Lu, Jigang Wang
The structure of the double-slits interferometer designed using this principle is distinctly shown in Figure 3(a). Here, p is the distance from the light source to the double-slits component, and q is the distance from the double-slits component to the CMOS camera. In Figure 3(a), the achromatic lens is used to modulate the wavefront of the light passing through the double-slits component to stabilize the interference pattern on the CMOS camera surface. It’s difficult to detect the amplitude of the far-field pattern without the achromatic lens, and the light path is longer. After adding the achromatic lens, the camera can be placed at the conjugate point of the light source to obtain a stable interference pattern. The achromatic lens is customized according to the design parameters from ACT508-xxx-A-ML series products of Thorlabs manufacturer. And the polarizer is utilized for obtaining the horizontal polarization light, and the filter is applied to obtain quasi-monochromatic light. It is necessary to use a monochromator instead of a filter to obtain quasi-monochromatic light when using shorter-wavelength light to measure the transverse beam size of the storage ring light source. At the same time, for the sake of facilitating the simulation, the error caused by the thermal deformation of these optical components is not considered. It is worth noting that the B8 interference system for measurements of horizontal and vertical beam size are so-called horizontal interferometer and vertical interferometer, respectively. The main difference between the two interferometers is the structural parameter of the double-slits components in the optical path, as shown in Figure 3(a).