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13 – Prism scale knob. A lensmeter or lensometer (sometimes even known as focimeter or vertometer), [1] [2] is an optical instrument used in ophthalmology. It is mainly used by optometrists and opticians to measure the back or front vertex power of a spectacle lens and verify the correct prescription in a pair of eyeglasses, to properly ...
Lens clock. A lens clock is a mechanical dial indicator that is used to measure the dioptric power of a lens. It is a specialized version of a spherometer. A lens clock measures the curvature of a surface, but gives the result as an optical power in diopters, assuming the lens is made of a material with a particular refractive index .
The PRISMA flow diagram, depicting the flow of information through the different phases of a systematic review. PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) is an evidence-based minimum set of items aimed at helping scientific authors to report a wide array of systematic reviews and meta-analyses, primarily used to assess the benefits and harms of a health care ...
Eyeglass prescription. Using a phoropter to determine a prescription for eyeglasses. 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.
In some offices, this process is used to provide the starting point for the ophthalmologist or optometrist in subjective refraction tests. Here, lenses are switched in and out of a phoropter and the patient is asked "which looks better" while looking at a chart.
Construction. The polarimeter is made up of two Nicol prisms (the polarizer and analyzer). The polarizer is fixed and the analyzer can be rotated. The prisms may be thought of as slits S1 and S2. The light waves may be considered to correspond to waves in the string.
Multiple prism beam expander using r prisms ( M B 0 1 M ) {\displaystyle {\begin{pmatrix}M&B\\0&{\frac {1}{M}}\end{pmatrix}}} M is the total beam magnification given by M = k 1 k 2 k 3 ··· k r , where k is defined in the previous entry and B is the total optical propagation distance [ clarification needed ] of the multiple prism expander.
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