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In optics and lens design, the Abbe number, also known as the V-number or constringence of a transparent material, is an approximate measure of the material's dispersion (change of refractive index versus wavelength), with high values of V indicating low dispersion. It is named after Ernst Abbe (1840–1905), the German physicist who defined it.
An optical instrument is said to be diffraction-limited if it has reached this limit of resolution performance. Other factors may affect an optical system's performance, such as lens imperfections or aberrations, but these are caused by errors in the manufacture or calculation of a lens, whereas the diffraction limit is the maximum resolution ...
The add segment of the lens for near vision is the D-shaped area. A bifocal is a lens with two sections, separated by a line (see image to the right). Generally, the upper part of the lens is used for distance vision, while the lower segment is used for near vision. The area of the lens that caters to near vision is called the add segment.
In optics, the Abbe sine condition is a condition that must be fulfilled by a lens or other optical system in order for it to produce sharp images of off-axis as well as on-axis objects. It was formulated by Ernst Abbe in the context of microscopes. [ 1] The Abbe sine condition says that. the sine of the object-space angle should be ...
July 26, 2024 at 12:49 PM. By Tom Hals. WILMINGTON, Delaware (Reuters) - A U.S. judge has blocked a Department of Labor rule from taking effect that would have expanded the types of retirement ...
Retirees typically get their income from Social Security and savings. For many, these two sources both fall short of providing what's needed. The average retirement account balance for retiree ...
Chromatic aberration. Focal length of lens varies with the color of light. In optics, chromatic aberration ( CA ), also called chromatic distortion, color aberration, color fringing, or purple fringing, is a failure of a lens to focus all colors to the same point. [ 1][ 2] It is caused by dispersion: the refractive index of the lens elements ...
The Employee Retirement Income Security Act of 1974 ( ERISA) ( Pub. L. 93–406, 88 Stat. 829, enacted September 2, 1974, codified in part at 29 U.S.C. ch. 18) is a U.S. federal tax and labor law that establishes minimum standards for pension plans in private industry. It contains rules on the federal income tax effects of transactions ...