Write a short notes on the prisms making use of total internal reflection.

Explanation

Prisms can be designed to reflect light by `90^@` or by `180^@` by making use of total internal reflection. In the first two cases, the critical angle ic for the material of the prism must be less than `45^@` . Ex. : Crown glass and flint glass. Prisms are also used to invert images without changing their size.