Figure 1
From: High accuracy determination of the thermal properties of supported 2D materials

An artistic illustration of the concept of the experiment.
Examined 2D material is placed onto the typical Si/SiO2 substrate. A Raman laser beam is simultaneously causing and probing the local temperature increase. Depending on the distance of the microscope objective from the sample surface, the beam spot on the sample has a different size, inducing a different temperature increase.