Neon spectra by direct vision prism

Physikfan, Fri Oct 21 2016, 11:45AM

A Neon spectral tube as a light source, a direct vision prism as the spectroscopic device and a digital camera are used to record a neon spectrum.
A power supply delivers 5000V and a maximum of 2 mA, protection resistor is required!


For demonstration of atomic spectra direct vision prisms are particularly suitable.
Three prisms of different refractive indices are arranged one behind the other, e.g. flint glass, crown glass, flint glass.


Exposure time around 1/150 second


Exposure time around 1/50


Exposure time around 1/10 second


Exposure time around 1 second

With increasing exposure time, the faint lines in green and blue are visible,
However, the strong red lines are then overexposed.

Please note the non-linear representation of the wavelength on the x-axis due to the nonlinear dependence of the refractive index of the glass prism as a function of the wavelength.