Types of Lenses

Depending on whether light rays are converging or diverging, there are two types of lenses. There are two types of lenses:

1. The convex lens (converging lens)
2. The concave lens (diverging lens)

Concave lens

The lens which is thicker at the end than the middle is called the concave lens. It is also called diverging lens as it spreads out the light rays that have been refracted through it. It has the ability to diverge the parallel beam of light.

A common application of concave lenses is that they are used in optical devices such as binoculars, telescopes, eyeglasses, spy holes in doors, etc. 

Convex lens

The lens which is thicker at the middle than the end is called a convex lens. It is also called a converging lens as it converges the parallel beam of light into a point.

A common application of convex lenses is that they are used in optical devices such as microscopes, telescopes, eyeglasses, magnifying glasses, etc. 

In optics, a ray is a geometrical representation of the light that is idealized by choosing a curve that is perpendicular to the wave fronts of actual light and points in the energy flow direction. Rays are used to represent the propagation of light through an optical system by separating the real light field into discrete rays that can be computationally carried through the system using ray-tracing techniques. This makes it possible to investigate or simulate even the most complex optical systems mathematically. Ray tracing is based on approximate solutions to Maxwell’s equations that hold true as long as light waves flow through and around objects with dimensions significantly greater than the wavelength of the light. Diffraction, for example, necessitates the study of wave optics, which is not addressed by ray or geometrical optics. Adding phase to the ray model can be used to describe wave phenomena such as interference in some instances.