Abstract
In this paper, we set up an experimental setup, which has a heterodyne interferometer, a phase meter, and a piezoelectric (PZT) stage for obtaining 10-pm-order mechanical displacement measurements. To suppress residual errors in the measurements, the interferometer combined with the PZT stage is placed in a vacuum chamber at low pressure. Next, the chamber, the heterodyne light source, and other optics are located on an antivibration that is enclosed by a sealed room. The phase meter is based on a phase-locked loop (PLL) [1] and programmed on a field-programmable gate array (FPGA) module. Mechanical displacements with a resolution of 10 pm order are implemented at 〜230 Pa and measured by the interferometer combined with the phase meter. The experimental result shows the combined system obtains a mechanical step displacement of 11 pm and a displacement noise floor of <0.2 pm/sqrt(Hz). The setup, the signal processing of the phase meter, experiments, and results are discussed. Reference [1] T.-D. Nguyen, Q.-A. Duong, M. Higuchi, T.-T. Vu, D. Wei, and M. Aketagawa, “19-picometer mechanical step displacement measurement using heterodyne interferometer with phase-locked loop and piezoelectric driving flexure-stage,” Sens. Actuators A Phys. 304, 111880 (2020).
