Measurement of photo-induced thermal radiation and temperature extraction in a metallic thin film subjected to a nanosecond laser pulse.

We present an instrument for measuring photo-induced thermal radiation in thin metallic films subjected to pulsed laser illumination in the nanosecond regime. The broad-band dynamic range obtained in the mid-infrared is on the order of 2 decades. The thermal radiation data are then used to extract the temporal evolution of the absolute temperature rise with nanosecond-scale resolution. The result is satisfactory in that no optical or thermal parameter is adjusted. The spatial profile of the excitation beam proves to be a key parameter in the temperature extraction.