A method of heat-treating a workpiece includes generating an initial heating portion and a subsequent sustaining portion of an irradiance pulse incident on a target surface area of the workpiece. A combined duration of the initial heating portion and the subsequent sustaining portion is less than a thermal conduction time of the workpiece. The initial heating portion heats the target surface area to a desired temperature and the subsequent sustaining portion maintains the target surface area within a desired range from the desired temperature. Another method includes generating such an initial heating portion and subsequent sustaining portion of an irradiance pulse, monitoring at least one parameter indicative of a presently completed amount of a desired thermal process during the irradiance pulse, and modifying the irradiance pulse in response to deviation of the at least one parameter from an expected value.