The eriometer is a little-known measuring instrument for determining fibre thickness by means of a diffraction effect. It goes back to the English physician and natural scientist Thomas Young, who sent one of the first eriometers by letter to his friend Sir Joseph Banks in 1810 and whose original can still be found in Thomas Young's estate at the Royal Institution. At the time, Thomas Young's theory of diffraction was still in the stabilisation phase and if it is claimed today that it can be traced back entirely to Young, this ignores the fact that he can certainly be seen as a follower of Newton's optics and merely introduced the theory of diffraction, the effects of which had long since been described by Newton or Grimaldi.

The eriometer in the HistoLab is a reconstruction work by our bachelor's student Phil Hanisch, who made a replica based on the device in London, with which the optical effects could be reproduced. His replica was tested as part of the thesis and delivered good qualitative and, in some cases, quantitative results.