USE OF A PHOTOACOUSTIC CELL AS A SENSITIVE LASER POWER-METER

A nonresonant photoacoustic cell having carbon black as absorbing material is found to work as a sensitive laser power meter with flat wavelength response. Calibration of the instrument made on the basis of Rosencwaig-Gersho theory is fairly accurate below the saturation region which can be raised by increasing the chopping rate of input laser beam. This device when used along with a commercial lock-in amplifier has a measuring range from 5 mu W to 10 W and is much more sensitive compared with similar devices employed to measure laser power where a gas medium is used as the absorber.