An apparatus including an illumination system to condition a radiation beam, a support to support a patterning device, the patterning device capable of imparting the radiation beam with a pattern in its cross-section to form a patterned radiation beam, a substrate table constructed to hold a substrate, a projection system to project the patterned radiation beam onto a target portion of the substrate, and a control system configured to: receive pattern data characterizing a pattern distribution, receive radiation data characterizing the radiation beam, determine a dissipation distribution of the pattern based on the pattern data and the radiation data, determine deformation of the pattern by applying the dissipation distribution in a thermo-mechanical model of the patterning device, and determine a control signal to control a component of the apparatus based on the deformation of the pattern.