1. Determination of Wavelength of Monochromatic Sodium Light.

2. Determination of Wavelength of He-Ne Laser or Diode Laser.

A) It consist of two plane front coated mirrors M1 & M2 and two exactly similar optically plane, parallel glass plates p1, p2. The plates p1 is partially silvered on         its one surface{Beam splitter & Compensating Plates  having surface flatness of λ/4(both faces)fitted on the aluminum base at 45º of the two reflecting         mirrors}

B) The mirror M1 & M2 are mounted vertically on two arms at right angles to each other ( fig. 1) . Their planes can be slightly tilted about vertical and         horizontal axes with the help of the screws provided at their backs. (Upper screw for vertical motion & lower screw for Horizontal Motion)

C) Motion of Micrometer is divided 1/5th through the lever arm

D) A telescope: with Ramsden  eyepiece & cross line graticule is fitted to count fringes.