Abstract: A method for characterizing particles producing heat when exposed to light. The method includes the steps of stimulating a particle sample alternatingly with homogenous light waves with at least a first wavelength and a second wavelength, detecting by a detector heat radiated by the particle sample as a result of the stimulation, thereby yielding time-dependent images of a modulated heat distribution pattern, converting the time-dependent image of the modulated heat distribution pattern into the frequency domain and demodulating the image of the modulated heat distribution pattern, and determining a physical property of the particle sample based on the at least one demodulated image of heat distribution.

Abstract: A sample holder for magnetic nanoparticle samples including a plurality of sample wells for holding a magnetic nanoparticle sample, which are distributed on a top surface of the sample holder. The sample wells are distributed such that a first distance between neighboring samples wells and/or a second distance between each peripheral sample well and a respective edge of the top surface of the sample holder and/or a third distance between a deepest point of the sample wells and a bottom of the sample holder is between 1 and 100 times greater than a thermal diffusion length of the sample holder material. The sample holder is used in a lock-in thermography system.