The pattern formation in thin liquid films on solid substrates induced by irradiative heating is investigated. A model to describe the evolution of both the film surface profile and temperature field in the system is developed, in which the energy absorption into the film and substrate, and the energy reflection to which optical absorption and interference contribute are taken into account. The model consists of a thin film equation that describes the time evolution of the film surface profile and a heat equation for the substrate. The former is obtained within the framework of the long-wave approximation, in which the fluid layer is assumed to be sufficiently thin compared to the lateral length scale, while the latter is unconstrained by the substrate thickness. In order to examine the interference effects on the pattern formation, focus is placed on a transparent film/absorbable substrate system irradiated by a monochromatic wave with laterally uniform intensity distribution. In such a case, the energy reflectance varies periodically with the film thickness due to optical interference. Numerical simulation results show that the stability of the film depends on the first derivative of the energy reflectance with respect to the film thickness at a reference point, and the resultant surface patterns, which include phase separation and periodic wavy patterns, differ depending on the reference thickness and initial perturbation. The stability revealed by the numerical results is confirmed by linear stability analysis of a simplified model.