A lens is a transmissive optical device that disperses or focuses a light ray by means of refraction. Concave means hollowed inward or curving in; so, concave lenses are hollowed inward. A concave lens is also called as a negative lens or a diverging lens. There are numerous uses of concave lens like in telescopes, cameras, lasers, glasses, binoculars, etc.
Some concave lens uses are listed in the points below.
A concave lens has at least one surface which is curved inwards, relative to the plane of the surface. The middle part of a concave lens is a lot thinner than the edges of the lens. When light rays fall, on a concave lens, the light rays bend outwards and diverge away from each other. The image formed upright and smaller than the actual object. Some interesting and common concave lens uses are given in the points below.
Used in telescope and binoculars
Concave lenses are used in telescope and binoculars to magnify objects. As convex lens create blurs and distortion, telescope and binocular manufacturers install concave lenses before or in the eyepiece so that a person can focus more clearly.
Concave lens used in glasses
Concave lenses are most commonly used to correct myopia which is also called as nearsightedness. The eyeball of a person suffering from myopia is too long, and the images of faraway objects fall short of the retina. Therefore, concave lenses are used in glasses which corrects the shortfall by spreading out the light rays before it reaches the eyeball. This enables the person to see far away objects more clearly.
Uses of concave lens in lasers
Different types of scanners, medical equipments, and CD and DVD players use laser beams. As the laser beams are highly focussed, they are dispersed so that the equipment works in a proper manner. Small concave lenses are used which widen the laser beam to sharply access a specific area.
Use of concave lens in cameras
To improve the quality of photographs combinations of convex and concave lenses are widely used by camera manufacturers. When only a convex lens is used as the primary lens of a camera it causes distortions in the photos which is called chromatic aberrations. Combining both concave and convex lens eliminated the undesirable effects.
Used in flashlights
Concave lenses are also used in flashlights in order to magnify the light produced by the source. The light rays fall on the hollowed side of the lens, and the light rays diverge on the other side. This increases the radius of the light source and thus provides a wider beam.
Concave lens used in peepholes
Peepholes or door viewers are security devices that give a panoramic view if objects outside walls or doors. A concave lens is used minimizes the proportions of the objects and gives a wider view of the object or area.
These were some uses of concave lens. Stay tuned with BYJU’S to learn more interesting Physics concepts with the help of interactive video lessons.