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A 1951 USAF resolution test chart is a microscopic optical resolution test device originally defined by the U.S. Air Force MIL-STD-150A standard of 1951. The design provides numerous small target shapes exhibiting a stepped assortment of precise spatial frequency specimens.
A person taking the test covers one eye from 6 metres or 20 feet away, and reads aloud the letters of each row, beginning at the top. The smallest row that can be read accurately indicates the visual acuity in that specific eye. The symbols on an acuity chart are formally known as "optotypes". Variation of Snellen chart with another letter ...
Near visual acuity or near vision is a measure of how clearly a person can see nearby small objects or letters.Visual acuity in general usually refers clarity of distance vision, and is measured using eye charts like Snellen chart, LogMAR chart etc. Near vision is usually measured and recorded using a printed hand-held card containing different sized paragraphs, words, letters or symbols.
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Figure 1 - Humphrey field analyser. Humphrey field analyser (HFA) is a tool for measuring the human visual field that is commonly used by optometrists, orthoptists and ophthalmologists, particularly for detecting monocular visual field. [1] The results of the analyser identify the type of vision defect.
Sloan letters, designed by Louise Sloan in 1959, are a set of optotypes used to test visual acuity generally used in Snellen charts and logMAR charts. This set of optotypes consists of ten specially formed "letters", C , D , H , K , N , O , R , S , V , and Z . [ 1 ]
Snell & Wilcox SW2 and SW4 "Zone Plate" Test Chart (also referred to as Snell & Wilcox Test Pattern) were TV test cards introduced in the 1990s and used with NTSC, PAL and SDTV systems. [1] Popular versions of the test charts were made available on Laserdisc and DVD-Video, allowing home users and professionals to test and calibrate their equipment.
The RMA 1946 Resolution Chart was transmitted by NTS and NOS in the Netherlands, SRG SSR in Switzerland, [18] VRT and RTBF in Belgium, RTP in Portugal, TVP in Poland, TVB in Hong Kong, [citation needed] Venevisión in Venezuela (525-lines variant; in conjunction with Indian-head test pattern), [citation needed] WISN-TV in Milwaukee, Wisconsin (525-lines variant) [19] and on low-powered ...