Magnifying glass

Magnifying glass . Optical instrument whose main part is a converging lens that is used to obtain an enlarged view of an object.


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  • 1 Physical Description
  • 2 Applications
  • 3 Operation
  • 4 Sources

Physical description

Mounted on a support, generally circular, which depending on its design and the specific use in a certain application, may or may not have a handle to facilitate handling or be mounted on a support. It consists of a converging lens with a short focal length, which deflects the incident light so that an enlarged virtual image of the object is formed behind it. The image is called virtual because the rays that appear to come from it do not actually pass through the magnifying glass. A virtual image cannot be projected on a screen just as it is seen, for example, on a flat polished surface.


The most common are to read texts with very small print, or to see in detail some particularity of a certain object.


It can be interpreted through the virtual and enlarged image it produces; but its correct use (it must be right in front of the eye , and the object must be in the focus of the lens, to obtain an image at infinity and a relaxed visualization, since the ciliary muscles are not working to focus at infinity) suggests another reasoning: since the size appreciated depends on that of the final image on the retina, given by the complete optical system (loupe plus eye), what allows the loupe is to obtain an angular magnification. Maximum angular size is achieved by bringing the object closer to the eye, but the eye is unable to focus at closer distances from the near point. The magnifying glass, superimposed on the eye, allows the latter to be brought closer, so that the object subtends a greater angle.

The loupes can be of different curvatures, and proportionally, the lens can have a certain degree of magnification. Generally, larger diameter loupes are more powerful (shorter focal length), since they allow a greater curvature of their surfaces, as the glass is necessarily narrow at the periphery and thick at the center. The electric magnifier or electrolupa is used in modern engineering (naval-aviation-nuclear, etc. since the beginning of the last century,


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