Dynamic phase microscopy: measurements of translational displacements at   sub-nanometer scale
  Dynamic phase microscopy has been applied for measurements of nanometer-scale displacements of a piezoelectric scanner. This scanner, which was designed for calibration purposes for scanning probe microscopy and TEM, exhibited a linear and hysteresis-free translation in the 0.05-20 nm range. The voltage-activated motion is described by a coefficient of 0.03 \pm 0.005 nm/V. 
V. P. Tichinsky, A. V. Kretushev, P. N. Luskinovich