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