Magnifier

A magnifier is an optical instrument that enlarges the apparent size of an object by increasing its angular size as seen by the eye. It typically uses a convex lens to bend light and produce a larger, upright image when the object is held close to the eye or placed under the lens. The amount of magnification depends on the lens’s focal length and the distances among lens, object, and eye. Shorter focal lengths yield greater magnification but can reduce working distance and field of view.

Common forms include simple handheld magnifiers (magnifying glasses) with short focal lengths that provide about 2x to 10x magnification; jewelers’ loupes, used for inspecting small details, with magnifications around 3x to 20x; reading glasses or lorgnettes for near vision; folding or pocket magnifiers; and digital or electronic magnifiers that use a camera and display, often with adjustable brightness, contrast, and color modes. Screen magnifiers and software-based magnifiers on computers or mobile devices enlarge text and images on the display.

Applications cover reading small print, crafting, electronics inspection, quality control, and general observation in education and science. Magnifiers aid the visually impaired by increasing legibility and contrast, with electronic or video magnifiers offering adjustable features such as magnification levels and enhanced illumination.

History notes that convex lenses for magnification were described in antiquity and by the medieval period in Europe and the Islamic world, with magnifying glasses becoming common tools for reading and scientific work by the 13th century. Today, magnifiers range from simple glass lenses to advanced digital devices, serving a broad set of everyday and professional needs.