Indent

To determine the strength of a material, such as this human dentine from a molar tooth, a diamond point is applied to the surface with a known force. The resulting indent diameter is related to how deep the diamond is able to penetrate the surface with that force. This image was acquired using a special incident light filter called circular differential interference contrast.

This method, therefore, measures density, which is of interest to many disciplines, including health science and materials science. We find it also interesting that this mark provides a record of an event and, as such, reflects the “culture” of science.