Precisely to find wave length of Monochromatic light on  calibrated scale L.C.0.001mm with Telescope. It has following  parts :-

1) Bed : Optically ground length 250 mm.

2) Main Round Screw : length 200 mm pitch 1mm for moving Mirror mount.

3) Surface coated mirrors with Mirror mount :  two nos , are  held in mirror mounts  which can to made parallel to each other with 3 screws(spring loaded)         provided at the rear of the each mirror.

4) Beam splitter & Compensating Plates of size 45 x 32 x 8 mm having surface flatness of λ/10(both faces).

5) Scale built-in to Main Knob : for moving Mirror No 1 least count 0.01 mm.

6) Slow motion drum for moving mirror No 2 least cunt 0.0001 mm.

7) Telescope with cross line graticule adjustable to & fro by movable screw for counting fringes.

8) Screws with nut & spring to adjust fringes in horizontal/vertical positions.

9) Diffused Glass screen with pin hole holder for sodium light