Meaning
High-precision mechanical position control methods using piezoelectric actuators adjust optical path lengths in phase-shifting interferometers to cancel phase errors caused by environmental vibration and thermal expansion drift. Incorporating piezoelectric phase compensation enables sub-nanometer surface topography measurements on polished mould inserts and optical polymer lenses under factory floor conditions. Actuators displace reference mirrors by tiny fractions of a light wavelength while feedback sensors track movement in real time.
Dynamic positioning maintains precise phase relationships during optical fringe data acquisition.
Phase Shifting
Controlled stepping of reference mirror positions creates precise interference fringe phase steps across recorded camera images. Integrating piezoelectric phase compensation guarantees exact ninety-degree phase shifts despite ambient building vibrations. Algorithms combine multiple phase-shifted intensity frames into wrapping phase maps.
Accurately stepped fringes yield high-resolution surface height maps.
Closed Loop
Strain gauge feedback sensors monitor actuator displacement to compensate continuously for non-linear movement and thermal expansion. Systems utilizing piezoelectric phase compensation rely on closed-loop digital controllers to maintain sub-nanometer positioning accuracy across long acquisition sweeps. Real-time feedback cancels drift caused by laboratory air currents.
High loop gain yields rapid response times.
Hysteresis Error
Mechanical displacement lag inherent in piezoceramic materials causes positioning errors during forward and reverse motion cycles. Active piezoelectric phase compensation algorithms use calibrated drive voltage curves to counteract non-linear crystal behavior. Uncompensated hysteresis distorts reconstructed surface profile data.
Calibration tables eliminate residual position errors.
