Search results
Results from the WOW.Com Content Network
Corrective lens. A corrective lens is a transmissive optical device that is worn on the eye to improve visual perception. The most common use is to treat refractive errors: myopia, hypermetropia, astigmatism, and presbyopia. Glasses or "spectacles" are worn on the face a short distance in front of the eye.
Abbe number. 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 ...
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 proportional ...
Optical aberration. 1: Imaging by a lens with chromatic aberration. 2: A lens with less chromatic aberration. In optics, aberration is a property of optical systems, such as lenses, that causes light to be spread out over some region of space rather than focused to a point. [1]
Progressive lenses are corrective lenses used in eyeglasses to correct presbyopia and other disorders of accommodation. They are characterised by a gradient of increasing lens power, added to the wearer's correction for the other refractive errors. The gradient starts at the wearer's distance prescription at the top of the lens and reaches a ...
In a multiple-lens system, each lens treats the previous lens's image as an object, and produces a new image of it, so that the imaging is cascaded through the lenses. This is easy to understand when the image from one lens is before the front focus of the next lens, but it remains true even when the intermediate image is located within the ...
The Corrective Optics Space Telescope Axial Replacement ( COSTAR) is an optical correction instrument designed and built by NASA. It was created to correct the spherical aberration of the Hubble Space Telescope ' s primary mirror, which incorrectly focused light upon the Faint Object Camera (FOC), Faint Object Spectrograph (FOS), and Goddard ...
Prism dioptres. Prism correction is commonly specified in prism dioptres, a unit of angular measurement that is loosely related to the dioptre. Prism dioptres are represented by the Greek symbol delta (Δ) in superscript. A prism of power 1 Δ would produce 1 unit of displacement for an object held 100 units from the prism. [2]