INSTRUMENTS

MICROSCOPES

The Magnifier 

Technical details: Processing/material quality.

Glas-lenses: made of minerai (crown or silicate)- glass, optically ground and polished, scratchprof, heat-resistant and antistatic. We have our own glass-grinding workshops, and decades of experience in processing and treatment of glass, ceramics carbide metals, etc... 

Lightweight lenses: made of organic material PMMA (plexi), optically pure, perfectly transparent, with antistastic treatment and surface protection. Produced in our own injection moulding workshop.
The aspherical lenses are well known among expert. A lot of the visual aids are provvided with these kind of lenses.

Metal mounting: rim of brass, highly polished, nickel-plated with anti-corrosion protection or genuine gold-plated. Thes give the lenses extra stability and high quality. 

Plastic mountings: transparent or slightly tinted plastic mountings facilitate binocular vision, which is particularly important when the reading glasses are used for a relatively long period, unlike the short-term use of high power magnifiers. Dark coloured mounting have the advantage of being reflexion-free.

Lens forms and systems.

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Special optical and other futures of the different lens systems: biconvex and plano-convex lenses are relatively inexpensive however, they have the disadvantage that hogh magnification causes distortions aound the edge. 
Asoherical lenses of comparable size produce however a higher magnification (than bi-conver and plano convex) ans are, to a large extent, free from distortions on the total lens surface, due to the different bend radii on the strongly convex side (aspherical). This strongly convex side must always face the eye.
Biconcave lenses are used for diminishing glasses. Aplanatic lens systems ensure an extremely well focusses visual field up to the edge of the lens.

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ASOTAL, the aspherical lightweight lens by SCHVEIZER ASOTAL is the brand name of aspherical lightweight lenses made by Sweizer. ASOTAL lens are made of optically pure plexiglas (PMMA) with the refractive index n = 1.49. 
The aspherical design of the lens surface improves the optical quality considerably. In comparison with spherical surfaces, the aspherical designed ASOTAL lenses allow hugher refractive power or larger diameters respectively, achieving very good  image quality at the same time.
The two surfaces of the ASOTAL lense mostly got different curvatures please note, that the surface with the stronger curvature must face the user in case of low and median magnifications. In case of high magnifications (from about 6X) and the corresponding short distance bbetween eye and lens, better image is achieved, when the surface with the stronger curvature faces the object.
Reading magnifiers however, due to their design of the mount and handle do not allow to realize, qhich side is the right one. Please oreintate by the Schweizer logo. It always marks the side with the stronger curvature.

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