Answer to Question #92958 in Optics for ROHIT SHARMA

Question

Highlight the advantages offered by Fresnel bi-prism arrangement for observing
interference patterns.

Answer 1

In Young’s Slits experiment, a single source is split in two coherent sources. For the Young’s slits experiment, we must approximate that the slits act as point sources. This however is not the case, since the slits have finite width. In this way, it gives rise to unwanted diffraction effects that causes errors. The Fresnel biprism experiment overcomes this problem.

A Fresnel biprism is a variation of Young’s Slits experiment. The biprism consist of two active angled prisms with their bases in contact. Monochromatic light through a narrow slit falls on biprism that divides it into two components. One of these component is refracted from upper portion of biprism and the other one refracted through lower portion. Two virtual coherent sources formed from the original source. In this case, two virtual coherent sources are point sources and replace slits in Young’s experiment.