Abstract: A method of determining the temperature of a sample carrier in a charged particle-optical apparatus, characterized in that the method comprises the observation of the sample carrier with a beam of charged particles, the observation giving information about the temperature of the sample carrier. The invention is based on the insight that a charged particle optical apparatus, such as a TEM, STEM, SEM or FIB, can be used to observe temperature related changes of a sample carrier. The changes may be mechanical changes (e.g. of a bimetal), crystallographic changes (e.g. of a perovskite), and luminescent changes (in intensity or decay time). In a preferred embodiment the sample carrier shows two bimetals, showing metals with different thermal expansion coefficients, bending in opposite directions. The distance between the two bimetals is used as a thermometer.