The invention relates to an STED (
stimulated emission depletion)-based device and method for measuring a smooth free-form surface sample, belonging to the field of the optical microscopic measurement. The device comprises a first
picosecond pulse
laser, a first conduction
optical fiber, a first
collimator objective, a first plane reflecting mirror, a second
picosecond pulse
laser, a second conduction
optical fiber, a second
collimator objective, a second plane reflecting mirror, a vortex-shaped
phase modulation plate, a half-wave plate, a first dichroscope, a second dichroscope, a quarter-wave plate, a focusing object lens, a
coating sample, a three-dimensional micro-displacement carrier table, an
optical filter, a
collection object lens, a pin hole and a photoelectric
detector. The surface of the sample is coated with a fluorescent membrane, so that an industrial sample can be measured by utilizing the STED
microscopy; meanwhile, the fluorescent membrane radiates
fluorescence in different directions under the illumination of the
laser, so that the problem that the
signal light is difficult to collect caused by the
mirror reflection of the
light beam on a smooth free-form surface can be avoided. By adopting the device and method, the surface appearance of the smooth sample with a large angle between a normal and the
optical axis direction can be high precisely measured.