Coherence and width of spectral lines with the Michelson interferometer
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.
- 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
Lens holder
Lens, mounted, f +20 mm
Lens, mounted, f +200 mm
Object holder, 5×5 cm
Iris diaphragm
Ground glass screen,50x50x2 mm
High pressure Hg Lamp, 50 W
Swinging arm
Optical bench expert, l = 1000 mm
Base for optical bench expert, adjustable
Slide mount for optical bench expert
Slide mount for optical bench expert, h = 30 mm
Colour filter, light green, 480…570 nm, 45% @ 525 nm
Diaphragm, 4 double slits
Michelson interferometer
Measuring magnifier
Slit, width adjustable up to 1 mm
Diaphragm holder, attachable
Power supply 230 V/ 50 Hz for 50 W-Hg-lamp
Stand tube
Barrel base expert
Lens holder, beam height 120 mm
- 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.
- 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