Biconvex Lens

Properties, Uses and Applications of Biconvex lenses


A lens is any transparent substance or a piece of glass with curved sides for dispersing or concentrating light rays that are used singly or with other lenses as in a telescope.

Types of lenses:

The lens can be classified mainly into two types. They are as follows:

  • 1. Convex lens:

  • A convex lens is also called a positive lens or a converging lens. The reason for why it is called a convex lens is that it makes parallel light rays to pass through it by bending inwards and converging at a spot just beyond the lens, which is known as the focal point.The plastic or glass surface present in the convex lens bulge outwards in the center providing the typical lentil shape.

    These lenses are used in binoculars and telescopes in order to bring distant light rays to focus in eyes.

  • 2. Concave lens:

  • The exact opposite of convex lens is the concave lens. Here, the outer surface is curved inwards making it parallel and the light rays curve outward or diverge. Concave lenses are also called as diverging lenses.

    Biconvex lens:

    The simple lenses comprising of two convex surfaces in spherical form, usually having the same kind of radius of curvature is known as Biconvex lens. The biconvex lens is also called a convex-convex lens.

    The biconvex lens has a broad range of applications, but it is not restricted to focusing and control of quality imaging, laser beams and other sorts of visual instruments. In a biconvex lens, an accurate parallel beam of light passes through the lens and converges at a focus or spot that comes behind the lens. The distance from the lens up to the focus is known as the focal length of the lens. There will be around two focal points and two centers since there is a curvature on both sides of the lens. The line that will be seen in the middle of this lens is called a principal axis. Following is the figure of it:

    The best example of a biconvex lens is the human eye. In order to view the objects on the hands, the light rays approaching from the objects should bend sharply for bringing them on to the focus of the retina. Less refraction is required for the light rays approaching from a distant object.

    Properties of Biconvex lenses:

    Following are some of the properties of the biconvex lens:

  • • Biconvex lens owns a positive focal length.

  • • In a biconvex lens, the focal lengths will be shorter.

  • • The ability to converge the incident light is present in the biconvex lens.

  • • The capabilities to form virtual, as well as real images, are present in these lenses.

  • • Using the conjugate ratio corresponding to unity, they can minimize the spherical deviation and also terminate the distortion and coma.

  • These lenses are said to be in symmetrical form with equal radii on both sides. Usually, these lenses will be recommended for a positive conjugate ratio ranging between 0.2 – 5. 

    Uses and applications of Biconvex lenses:

  • • The biconvex lens is used as a condensing or magnifying lens.

  • • Also, they can be used as magnifiers or objectives.

  • • In many of the imaging systems like monocular, microscopes, telescopes, cameras, binoculars, projectors etc these lenses are utilized.

  • • In the case of the human eye, these lenses are used in producing virtual images and in the case of an optical sensor or photographic films, they are used in producing real images.

  • • The biconvex lens can also be used as a burning-glass.

  • • They are also used in various industries and also in the applications of image relays.

  • On the other hand, a biconvex lens, which is one of the best lenses that can be used where a beam of light incident on the lens is diverging in nature. Also, the beam that leaves the lenses symmetrically converges.