Linen tester

A thread count is a detailed magnifying glass with a three -to twelve- fold magnification on a (mostly folding ) frame for achieving a defined working distance. This distance depends on the magnification and the focal length of the microscope. The thread count should not be confused or equated with the magnifier, despite some similarities.

Construction

Typically, a thread count of three metal or plastic surfaces is made, which are connected by two hinges hinged together. The height of the central support surface specifies both the measure of the working distance. Set up ready to use is usually a circular aperture as a mount for the detailed motion, folded it lies between the other two and is protected during transport in the upper surface. The magnifying glass is usually only a single lens. Lens combinations such as achromats or aplanats are rare.

The footplate is regularly broken square. The edge length of this breakthrough usually are 10 x 10 mm, or 1 "x 1" ( inch = 25.4 mm). Other dimensions are also common.

Use

Was invented in the thread counter to check substances. In the textile so that the number of weft and warp threads in a specific area can be counted. In the carpet trade thread counter can be used to determine the number of nodes per area at knotted rugs.

Thread counter is used in other industries:

In the printing and publishing industry in prepress often judging of artwork to the printing machine for scanning and register control.

In the graphic design industry Fadenzähler were before the introduction of computer-based desktop publishing (DTP ) is used until the mid -1980s to assess the accuracy of manually -built on special cardboard using ink and rulers final drawings.

Also in the production of printed circuit boards and in the manufacturing of printed circuit boards of the thread counter is used as a simple magnifying and test instrument.

Problems with vision-impaired users

Users with refractive error, especially those with hyperopia or presbyopia, the object to be observed often do not look sharp enough. Since the distance of the object motion by design can not be changed, there is a problem here.

Special designs

In addition to specific, dependent on the intended use, dimensions of Fußdurchbruchs also thread counter with a reticle and engraved scale can be used in. Linen tester with reticle are a " transition " for measuring magnifier that is not foldable and usually at the magnifying glass ( often lens systems as an achromatic aplanatic or, more recently, aspherical lenses) is slidably guided in a tube. Through this leadership to meet the individual refractive error of the user is possible.