A system for thermal nanolithography comprises a cantilever (13) with a nanoscale tip (14) in proximity to a substrate surface (22). A probe light beam (L1) is reflected off the cantilever (13) and the reflected beam (R1) is measured to determine an atomic force interaction (F) between the tip (14) and the substrate surface (22). The tip (14) is heated to cause a heat-induced change at a localized part (22a) of the substrate surface (22) in proximity to the tip (14) by a heat flow (H) from the tip (14) to said localized part (22a). As described herein, the tip (14) is heated by absorption (A2) of a second, heat-inducing light beam (L2) that is distinct from the probe light beam (L1), in particular having a distinct wavelength (λ2) or other properties.