Optical trapping based method for in-situ calibration of displacement of piezoelectric platform

The invention provides an optical trapping based method for in-situ calibration of displacement of a piezoelectric platform. High-precision detection of motion displacement amplitude and frequency of the piezoelectric platform can be realized by analysis of position signals of Brownian motion of standard-size globules trapped in an optical trap system. Besides detection of the piezoelectric platform, standard particles are trapped by laser under microscopic imaging, and position motion signals of the particles are quickly detected by a detector. The piezoelectric platform sends low-frequency fixed-amplitude motion signals to drive a sample chamber to move, the particles trapped in a light trap is subjected to actions of fluid periodic viscous resistance, and voltage proportionality coefficient of a position sensitive detector can be calibrated by detecting the motion signals of the particles. The piezoelectric platform sends signals to drive the sampling chamber to move again, a power spectrum of the trapped particles is analyzed, a peak of the power spectrum is compared with background thermal noise to invert real motion displacement amplitude of the piezoelectric platform, and frequency of the peak stands for motion frequency of the piezoelectric platform.