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Definition: optical lenses held above objects because that viewing them v some moderate magnification

Alternative term: hand lenses

More general term: lenses

German: Vergrößerungsgläser

Categories: basic optics, vision, displays and also imaging

How to mention the article; suggest additional literature

Author: Dr. Rüdiger Paschotta


Magnifying glasses space a basic optical tools used for viewing details the objects with some magnification.They are periodically regarded together being the same as loupes, but precisely speaking a loupe is supplied in a close distance from the eye, while magnifying glasses (or hand lenses) are held at a larger distance.Magnifying glasses are frequently used in a bigger distance from the eye, space themselves larger and typically have a longer focal size of 125mm or more.

Such a maker typically consists of a single lens, i m sorry modifies the course of irradiate by refraction.The lens is usually mounted in a frame with a handle.


Figure1: A flower seen v a magnifying glass. Keep in mind that if one focuses on the object, the glass itself and its holder space no longer sharp. © Christine Kirchrath Paschotta.The imaging properties of a magnifying glass must constantly be thought about in associate of those v the human being eye.The magnification that a loupe is characterized as the ratio of the parental object sizes as observed with and without the glasses.For reading a publication with small letters, for example, one may organize a magnifying glass in a far-ranging distance native the eye, closer to the review text.When calculating the magnification based upon a comparison of monitoring with and without the magnifying glass, but each time indigenous the same relatively big distance, one obtains the magnification to be 1 to add the proportion of photo distance and also focal length.

Usually, the magnification that a simple magnifying glass is in between 2 and also 6.Higher magnifications would cause a reduced image quality, as lengthy as a basic lens is used.There are enhanced multi-lens designs, e.g. Triplet magnifiers, which carry out substantially higher magnification (up to about 30), yet with a tiny field that view and less light throughput.They generally need come be organized close come the eye, and should therefore be referred to as loupes.Four greater magnifications, one offers microscopes.

Interestingly, the eye can accommodate such that either the review text or the glass chin (or the mount) is sharp.

Magnifying glasses deserve to simply be made together spherical biconvex glass lenses.For a no too big field the view, the solution might be satisfactory.Plastic optics are often used rather of glass, and also then it is commonly not a difficulty to do an aspheric lens.

Aplanatic glasses, consists of two plano-convex lenses, with the convex surface on the inner side, are renowned as reading glasses, since they exhibit low image distortions.

Particularly huge magnifying glasses might be do in the type of Fresnel lenses (e.g. Together thin sheet magnifiers), yet then with decreased image quality.

The required illumination that the object may be done through the lens and/or from the side.Illumination with the lens deserve to have the advantage that the is brighter, through some concentration that the irradiate by the lens.On the other hand, one might then be disturbed by parasitic reflections, if the lens does not have reliable anti-reflection coatings.

There are likewise magnifying glasses with combined battery-powered illumination.

A magnifying glass can additionally be provided as burning glass, concentrating sunlight light such the a product like paper in the focal plane can it is in incinerated.

The same effect can produce a safety hazard; that can happen that a fire inadvertently arises from a magnifying glass, e.g. When displayed in a shop window.It is recipient to appropriately cover magnifying glasses when they room not in use.


The RP Photonics Buyer"s Guide includes 5 providers for magnifying glasses.

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See also: loupes, lenses, magnification, microscopesand other short articles in the categories general optics, vision, displays and also imaging


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