New optical power sensors using pyrolytic graphite

We present two experimental configurations based on a repulsion force acting on a piece of pyrolytic carbon (PyC) in a magnetic induction generated by a magnet array to measure a laser power in the range from a few milliwatts to a few watts. The levitation configuration consists in measuring the levitation height change of the PyC sheet related with the optical power irradiating its surface. The weighing configuration consists in measuring the mass change corresponding to a magnetic repulsion force change acting on a piece of PyC placed on a balance pan and irradiated by a laser beam. The quantities affecting the measurement results have been identified. Examples of measurement results are given. The relative uncertainty of optical power measurement is less than 10% for the first experimental set-up and around 1% for the second one. The wavelength dependence on power response of this device has been quantified. The two PyC-based devices presented in this paper offer a new technique for measuring optical power.