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2. Abbe number - Wikipedia

   en.wikipedia.org/wiki/Abbe_number

   In optics and lens design, the Abbe number, also known as the Vd-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 Vd indicating low dispersion. It is named after Ernst Abbe (1840–1905), the German physicist who defined it.

3. Chromatic aberration - Wikipedia

   en.wikipedia.org/wiki/Chromatic_aberration

   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 varies ...

4. Corrective lens - Wikipedia

   en.wikipedia.org/wiki/Corrective_lens

   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.

5. Diffraction-limited system - Wikipedia

   en.wikipedia.org/wiki/Diffraction-limited_system

   Memorial in Jena, Germany to Ernst Karl Abbe, who approximated the diffraction limit of a microscope as = ⁡, where d is the resolvable feature size, λ is the wavelength of light, n is the index of refraction of the medium being imaged in, and θ (depicted as α in the inscription) is the half-angle subtended by the optical objective lens (representing the numerical aperture).

6. Abbe sine condition - Wikipedia

   en.wikipedia.org/wiki/Abbe_sine_condition

   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 ...

7. A vet’s guide to Von Willebrand Disease in dogs - AOL

   www.aol.com/vet-guide-von-willebrand-disease...

   Just to reassure you though, that the most common form of von Willebrand disease in dogs is mild and has a near-normal life expectancy. ... Dogs with Type 3 vWD have values of 1% or less.

8. AOL Mail

   mail.aol.com

   You can find instant answers on our AOL Mail help page. Should you need additional assistance we have experts available around the clock at 800-730-2563.

9. Eyeglass prescription - Wikipedia

   en.wikipedia.org/wiki/Eyeglass_prescription

   An eyeglass prescription is an order written by an eyewear prescriber, such as an optometrist, that specifies the value of all parameters the prescriber has deemed necessary to construct and/or dispense corrective lenses appropriate for a patient. If an eye examination indicates that corrective lenses are appropriate, the prescriber generally ...