Realization and thermal characterization of thin-film optothermal microsensor

The aim of this investigation is to study thin-film thermoelectric linear arrays for high spatial temperature measurements and to analyze power laser energy profile. The sensitive area consists of a planar of 16 individual thin-film Au-Pd thermocouple junctions with 8 mum x 8 mum of surface area. This sensor allows 16 temperature measurements per 288 mum. It is processed by means of standard integrated circuit techniques. Thermal simulation of heat conduction in gold and palladium layers has been carried out. The sensor thermoelectric response has been characterized in transient regime and steady state. The time constant of thermocouple response is of the order of 140 mus. A linear relationship between the thermoelectric voltage and the incident power laser has been put in evidence. Using the linear array, a Gaussian profile of the incident laser beam is obtained.