Principle

The wavelengths and the corresponding lengths of coherence of the green spectral lines of an extreme high pressure Hg vapour lamp are determined by means of a Michelson interferometer. Different double slit combinations are illuminated to verify the coherence conditions of non punctual light sources. An illuminated auxiliary adjustable slit acts as a non punctual light source.

Benefits


study the quantity that allows light to be used in interference experiments

analyze different spectral lines of a mercury lamp

make practical use of a Michelson interferometer to characterize light


Tasks


Determination of the wavelength of the green Hg spectral line as well as of its coherence length.

The values determined in 1. are used to calculate the coherence time and the half width value of the spectral line.

Verification of the coherence condition for non punctual light sources.


What you can learn about


Fraunhofer and Fresnel diffraction

Interference

Spatial and time coherence

Coherence conditions

Coherence length for non punctual light sources

Coherence time

Spectral lines (shape and half width value)

Broadening of lines due to Doppler effect and pressure broadening

Michelson interferometer

Magnification