What is the principle of magnifying glass? According to what natural principle is a magnifying glass made?

Magnifier is imaged by the principle of refraction of light, which is essentially refraction of light. In order to see the tiny object or the details of the object clearly, it is necessary to move the object closer to the eye, which can increase the viewing angle and form a larger real image on the retina. But when the object is too close to the eye, it is not clear.

Magnifier is a simple visual optical device, which is used to observe the tiny details of objects. It is a convergent lens, and its focal length is much smaller than the apparent distance of the eyes. As early as more than 1000 years ago, people have ground transparent crystals or transparent gems into "lenses", which can enlarge images. The traditional magnifying glass lens is made of glass and is a bit heavy; More valuable is made of rare minerals, such as rubies, sapphires and agates.