A magnifying glass (called a hand lens in laboratory contexts) is a convex lens which is used to produce a magnified image of an object. The lens is usually mounted in a frame with a handle (see image). This article is about the optical device. ... Magnification is the process of enlarging something only in appearance, not physical size. ... Look up image in Wiktionary, the free dictionary. ... This article is about the optical device. ...

A magnifying glass works by creating a magnified virtual image of an object behind the lens. The distance between the lens and the object must be shorter than the focal length of the lens for this to occur. Otherwise, the image appears smaller and inverted, and can be used to project images onto surfaces. Top: The formation of a virtual image using a concave lens. ... This article is about focal length related to lenses and systems of lenses. ...

Magnifying glass on an arm lamp

The framed lens may be mounted on a stand, keeping the lens at the right distance from the table, and therefore at the right distance from the object on the table. The latter applies if the object is small, and also if the height is adjustable. Some magnifying glasses are foldable (from the handle or stand). Download high resolution version (750x1143, 66 KB)Magnifying glass, US Navy Newsstand photo, PD 030903-N-2143T-001 Central Command Area of Responsibility (Sept. ... Download high resolution version (750x1143, 66 KB)Magnifying glass, US Navy Newsstand photo, PD 030903-N-2143T-001 Central Command Area of Responsibility (Sept. ...

A sheet magnifier consists of many very narrow concentric ring-shaped lenses, such that the combination acts as a single lens but is much thinner. This arrangement is known as a Fresnel lens. Not to be confused with Fresnel lantern. ...

A loupe is a small magnification device used by surgeons, dentists, jewelers, watchmakers, and other precision craftsmen. The magnification of jewelers' loupes for studying gemstones is typically on the order of 10×.^[1] A magnifying glass A magnifying glass is a single convex lens which is used to produce a magnified image of an object. ... Surgery Surgery is the medical specialty that treats diseases or injuries by operative manual and instrumental treatment. ... X-rays can reveal if a person has cavities Dentistry is the practical application of knowledge of dental science (the science of placement, arrangement, function of teeth) to human beings. ... Jewellery (Jewelry in American spelling) comprises ornamental objects worn by persons, typically made with gems and precious metals. ... A watchmaker is one who primarily repairs watches, although historically this person also made watches. ...

The magnifying glass is an icon of detective fiction, particularly that of Sherlock Holmes. Basil Rathbone as Sherlock Holmes Detective fiction is a branch of crime fiction that centers upon the investigation of a crime, usually murder, by a detective, either professional or amateur. ... A portrait of Sherlock Holmes by Sidney Paget from the Strand Magazine, 1891 Sherlock Holmes is a fictional detective of the late 19th and early 20th centuries, who first appeared in publication in 1887. ...

Visually impaired people often benefit from magnifying glasses and similar low vision aids. Blindness can be defined physiologically as the condition of lacking sight. ... Low vision is alternatively a general term used to describe lowered visual acuity, and a specific legal term in Canada and the United States used to designate someone with vision of 20/70 or less in the better eye with correction. ...

Roger Bacon is the original inventor. For the Nova Scotia premier see Roger Bacon (politician). ...

Magnification

The magnification of a magnifying glass depends on where it is placed between the user's eye and the object being viewed, and the total distance between the eye and the object. Magnifying glasses are typically described in terms of their magnifying power, which is equivalent to angular magnification (this should not be confused with optical power, which is a different quantity). The magnifying power is the ratio of the sizes of the images formed on the user's retina with and without the lens.^[2] For the "without" case, it is typically assumed that the user would bring the object as close to the eye as possible without it becoming blurry. This point, known as the near point, varies with age. In a young child it can be as close as 5 cm, while in an elderly person it may be as far as one or two metres. Magnifiers are typically characterized using a "standard" value of 0.25 m. Magnification is the process of enlarging something only in appearance, not physical size. ... Magnification is the process of enlarging something only in appearance, not in physical size. ... Optical power or dioptric power or refractive power is the degree to which a lens or mirror converges or diverges light. ... Presbyopia (Greek word presbyteros (πρεσβύτερος), meaning elder) is the eyes diminished ability to focus that occurs with aging. ...

The highest magnifying power is obtained by putting the lens very close to the eye and moving the eye and the lens together to obtain the best focus. The object will then typically also be close to the lens. The magnifying power obtained in this condition is MP₀=¼Φ+1, where Φ is the optical power in dioptres, and the factor of ¼ comes from the assumed distance to the near point. This value of the magnifying power is the one normally used to characterize magnifiers. It is typically denoted "m×", where m=MP₀. This is sometimes called the total power of the magnifier (again, not to be confused with optical power). A dioptre, or diopter, is a non-SI unit of measurement of the optical power of a lens or curved mirror, which is equal to the reciprocal of the focal length measured in metres (i. ...

Magnifiers are not always used as described above, however. It is much more comfortable to put the magnifier close to the object (one focal length away). The eye can then be a larger distance away, and a good image can be obtained very easily; the focus is not very sensitive to the eye's exact position. The magnifying power in this case is roughly MP=¼Φ.

A typical magnifying glass might have a focal length of 25 cm, corresponding to an optical power of 4 dioptres. Such a magnifier would be sold as a "2×" magnifier. In actual use, an observer with "typical" eyes would obtain a magnifying power between 1 and 2, depending on where lens is held. An older person might obtain an actual magnifying power of 8 or more with this lens, however, due to the eye's longer near point distance. This article is about focal length related to lenses and systems of lenses. ...

Magnifying glass is also a suitable optical element for low-cost FSO data transmission systems.

Image File history File linksMetadata Download high-resolution version (1632x1224, 942 KB) File links The following pages on the English Wikipedia link to this file (pages on other projects are not listed): Magnifying glass Metadata This file contains additional information, probably added from the digital camera or scanner used to... Image File history File linksMetadata Download high-resolution version (1632x1224, 942 KB) File links The following pages on the English Wikipedia link to this file (pages on other projects are not listed): Magnifying glass Metadata This file contains additional information, probably added from the digital camera or scanner used to... Free Space Optics (FSO) is a telecommunication technology that uses light propagating in free space to transmit data between two points. ...

See also

Wikimedia Commons has media related to:

Magnifying glass

• Burning-glass
• Eyeglasses
• Screen magnifier
• Loupes

Image File history File links Commons-logo. ... A burning-glass is a large convex lens that can concentrate the suns rays onto a small area, heating up the area and thus resulting in ignition of the surface exposed. ... A pair of modern glasses Glasses, also called eyeglasses or spectacles are frames, bearing lenses worn in front of the eyes normally for vision correction, eye protection, or for protection from UV rays. ... A screen magnifier is software that interfaces with a computers graphical output to present enlarged screen content. ... A loupe. ...

References

1. ^ Wickell, Carly. Jeweler's Loupe (HTML). About: Jewelry / Accessories. About.com. Retrieved on 2007-02-20.
2. ^ Hecht, Eugene (1987). Optics, 2nd ed., Addison Wesley, p. 186-188. ISBN 0-201-11609-X.