Myopia glasses are concave lenses. The image formed by a concave lens is always smaller than the upright virtual image of the object. Concave lenses are mainly used to correct myopia. Myopia is mainly caused by the deformation of the lens, which causes light to focus prematurely in front of the retina.
The concave lens plays the role of diverging light. The concave lens forms an upright, reduced virtual image, which lengthens the image distance and just falls on the retina. Hyperopia (presbyopia) uses convex lenses.
Myopia glasses are glasses that need to be worn in order to see clearly in the distance after myopia. Myopia glasses are used to correct vision so that distant objects can be seen clearly.
In order to maintain a certain adjustment ability of the ciliary muscle of the eyeball. Because distant light cannot be focused on the retina, distant objects cannot be seen clearly. However, after wearing myopia glasses, clear objects can be obtained, thereby correcting vision.
Extended information
Concave lenses are divided into three types: biconcave, plano-concave and convex-concave lenses. The line connecting the centers of curvature of its two surfaces is called the principal axis, and the central point O is called the optical center. Light passing through the optical center is not refracted no matter where it comes from.
The beam of light parallel to the main axis is refracted by the concave lens and then diverged in all directions. The extension line opposite to the direction of divergence will be at a point F on the same side as the light source. The refracted light rays will be emitted from point F. , this point is called virtual focus.
There is one on each side of the lens. Concave lenses are also called divergent lenses. The focal length of a concave lens refers to the distance from the focus to the center of the lens. The larger the radius of the lens, the longer its focal length. If it is a thin lens, the focal lengths on both sides are equal.
Baidu Encyclopedia-Concave Lens