The piezoelectric transducer(PZT)is a key component for variable-cavitylength laser in synthetic aperture laser radar systems.So it is necessary to measure the displacement of PZT with a high accuracy.A novel method using double-beam interferometry based on the best estimation of pattern gray scale was proposed.Through designing the estimation algorithm in the method,it was theoretically possible to get the measuring accuracy order to 1/1 024 of the laser wavelength.The experimental results from a PZT pipe ...