Third configuration: Radiation force meter based on a torsional spring-mass-damper system consisting of a small pyrolytic carbon disk levitated above a permanent magnet array. (a) Photograph of the passive sensitive system showing:− arrangements of nine cubic NdFeB magnets (10 mm × 10 mm × 10 mm); −levitated PyC disc (diameter: 20 mm); − three polyamide spheres (diameter: 3 mm); − square cover glass (18 mm × 18 mm); − two right-angle prism mirrors (one used for measuring the angular deflection, the other illuminated by the laser beam under test). (b) Example of response in terms of voltage given by a position sensitive detector measuring the angular deflection displacement of the detection laser beam to a 1 W radiation step for 5 s (red square signal) provided by the laser under test.