Measure The wavelength of light (sodium vapour lamp) source using Michelson's Interferometer. (ME 870)

To measure the wavelength of light (sodium vapour lamp)
source using Michelson's interferometer.
Setup comprises of:
Light Source:35 Watt Sodium vapour lamp housed in
powder coated Steel cabinet with Transformer & Stand
Michelson's interferometer
1) Pin hole in a black aluminium disc.
2) Glass diffuser disc.
7) Fine movement - Least count 10-4mm.
8) Telescope - It is a short focal length telescope with 
rack and pinion arrangement to be mounted on a rod fitted
in the instrument.
For more details please refer datasheet.