INTERFEROMETRIC METHOD FOR THE OBSERVATION IN REAL-TIME OF SOME INFRARED PHOTOTHERMAL EFFECTS

We present here an original experimental method utilising the interfer ence between two He-Ne laser beams for the detection of photothermal p henomenon on semiconductor at 10,6 mum. A JAMIN interferometer splits the beam of one He-Ne laser in two parallel beams. The first one under goes a transverse photothermal deflection due to its passage in a zone disturbed by a pump laser (the CO2 laser emits in the vicinity of 10 mum), the second beam serves as a reference. The experimental setup is very stable and is also extremely accurate. It allowed us to observe in real time the change of the temperature both during and after a pul se of the pump laser on a sample of silicon. We present here the descr iption of the experimental setup, the conditions of measurements and t he first results.