Significations et usages de loupe

From Wikipedia

A loupe (pronounced loop) is a type of magnification device used to see small details more closely.

Optics of loupes

Three basic types of loupes exist. The first is a simple lens and results in the least amount of magnification. The second is the Galilean system which uses multiple lenses, resulting in higher magnification. The last is the prismatic loupe system which employs both lenses and prisms to reflect and focus light, resulting in the highest degree of magnification.

Commercial uses of loupes

Loupes are used in a number of diverse industries, notably the jewelry trade, watchmaking, photography, printing, dentistry, geology, and ophthalmology.

Jewelers

Jewelers typically use a monocular, handheld loupe in order to magnify gemstones and other jewelry that they wish to inspect. ^[1] A 10x magnification is good to use for inspecting jewelry.^[1] A 10x loupe is the standard instrument used to determine a diamond's clarity grade in the gemological industry. While higher-power magnification devices may be used to examine the stone, inclusions (internal flaws) and blemishes (surface irregularities) are not factored into the stone's final clarity grade if they are small enough to be undetectable when the stone is examined under 10x magnification.^[2]

Watchmaking

Loupes are employed to assist watchmakers in assembling mechanical watches. Many aspects require the use of the loupe, in particular the assembly of the watch mechanism itself, the assembly and details of the watch dial, as well as the formation of the watch strap and installation of precious stones onto the watch face.

Photography

Photographers use loupes to review, edit or analyze negatives and slides on a light table. Photographers using large format cameras also use a loupe to view the ground glass image to aid in focusing.

Printing

Offset and flexographic printing see frequent use of loupes in order to carefully analyze how ink lays on paper. Strippers use loupes in order to register film separations to one another. Pressmen use them to check registration of colors, estimate dot-gain, and diagnose issues with roller pressure and chemistry based on the shape of individual dots and rosettes.

Dentistry

Many dentists use loupes to better scrutinize the entities within their patients' mouths in order to make a better diagnosis, for example, to determine how far a crack proceeds along the surface of a tooth. Loupes are also used in order to perform on a more precise level; while dentists drill teeth on a millimeter scale, magnification can enlarge the dentists' view of the teeth, perhaps^{[clarification needed]} making it easier to inspect teeth for decay and/or see things that ordinarily would not be seen without magnification.

Specialties of dentistry, such oral surgery and periodontics, may^{[clarification needed]} benefit from the use of loupes as well. The oral cavity is notorious for being a place containing small entities with limited access. Magnification can be very helpful when suturing a flap.

Because dentists use both of their hands while performing dental procedures, dental loupes are binocular and usually take on the form of a pair of glasses. Some dental loupes are flip-types, which take the form of two small cylinders, one in front of each lense of the glasses. Other types are inset within the lense of the glasses. A typical magnification for use in dentistry is 2.5x, but dental loupes can be anywhere in the range from 2x to 5x.

Together with proper access to the oral cavity, light is an important part of performing precision dentistry. Because a dentist's head often eclipses the overhead dental lamp, loupes may be fitted with a light source. Loupe-mounted lights used to be fed by fiber optic cables that connected to either a wall-mounted or table-top light source. Newer models feature a more convenient LED lamp within the loupe-mounted light and an electric cord coming from either the conventional wall-mounted/table-top light source or a belt clip rechargeable battery pack. Options for loupe-mounted cameras and video recorders are also available.

Surgery

Surgeons in many specialties commonly use loupes when doing surgery on delicate structures. The Loupes used by surgeons are mounted in the lenses of glasses and are custom made for the individual surgeon, taking into account their corrected vision, interpupillary distance and desired focal distance. Multiple magnification powers are available.

Geology

The loupe (hand lens) is a vital^{[citation needed]} geological field-tool used to identify rock's constituent minerals.

Entomology

Loupes are popular^{[citation needed]} among professional and amateur field entomologists for help identifying insects in field situations where a full-sized microscope is impractical, but the ability to observe small morphological characteristics is desired.

Electronics

Due to the extremely small size of many modern surface-mount components used in compact electronics, engineers often use a loupe to inspect the completed circuit board for manufacturing defects such as solder bridging and missing or misaligned components. While soldering or reworking surface-mount components by hand, a loupe is sometimes essential for identifying and aligning parts. Due to the ever-decreasing size of electronic components, the need for magnification is increasingly becoming a factor in circuit-building.

Tattooing

Tattoo artists use loupes to inspect the quality of their needle tips. They do this to ensure the least amount of damage possible to the skin surface.

Numismatists

Coin collectors use loupes to better evaluate the quality of coins. Identifying surface wear is vital when attempting classify the grade of a coin. Uncirculated coins (coins without wear) can command a substantial premium over coins with slight wear. This wear cannot always be seen with the naked eye.

See also

• Magnifying glass

References

1. ↑ ^{1.0 1.1} Jewelry - How to Use a Loupe - Using Jewelry Magnifiers
2. ↑ What is the GIA Clarity Scale for diamonds?