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PubMed · 2779986

Visolett magnifier without and with bifocal.

G E Fonda
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Abstract

Visolett nonfocusable magnifiers are optically designed paperweights. The general magnification is 1.8X, and 4X through the bifocal. Using glass index 1.806, the general magnification is 2.47X. A Visolett is one of the most useful nonspectacle magnifiers because it diffusely concentrates the illumination on the field of vision, complementing the magnification. The optics differ from hand-held and stand magnifiers, in that the magnification does not increase with the dioptric power. However, the magnification of the bifocal does increase with the dioptric power and by decreasing the distance of the object from the focal point. The advantages are that they are simple to use, allow binocular vision, and almost double the magnification when used with a spectacle magnifier. Visoletts are preferred to stand magnifiers.

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BibTeXRIS

G E Fonda. 1989. Visolett magnifier without and with bifocal.. https://doi.org/10.1016/s0161-6420(89)32984-8

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