An absolute calorimeter for high power CO₂laser

An easy to operate absolute calorimeter has been successfully built and calibrated in order to measure the energy output of a high power TEA CO 2 laser. The laser beam is completely absorbed in a plastic foil glued on a copper plate. A thermocouple measures the difference of temperature between two separate sandwiches of Plexiglas and copper plates, one of them taken as reference. Tested between 1 and 15 J at 10.6 mu m, the device showed an accuracy of 5%. In the best case, the maximum absorbed power could reach 80 MW cm -2 without any visible damage to the calorimeter. Such calorimeters are particularly convenient for the energy measurement of a high power laser with large beam cross section.