Sub-Nanometer Resolution Displacement Measurement by Heterodyne Interferometer with a Holographic Displacement Sensor

摘要

In this paper, we develop and demonstrate a displacement sensor comprised of a holographic plate integrated with a heterodyne interferometer. The holographic displacement sensor is mounted on the motorized stage and two diffracted lights will diffract and propagate on the x-z plane for x-direction displacement measurement. Based on the optical configuration, the p-polarized light coming from the +1st order diffracted beam will interfere with the s-polarized light coming from the -1st order diffracted beam. Similarly, the p-polarized light coming from the -1st order diffracted beam will interfere with the s-polarized light coming from the +1st order diffracted beam. This being a true phase detection heterodyne interferometer, the displacement can be obtained by analyzing of these two interference signals. The results show a 4 pm displacement variation of the PZT actuator can be observed. And there was no significant difference between our method and the comparison method in the result of 1.2 μm displacement measurement. Furthermore, the theoretical sensitivity and the uncertainty can reach to 0.5 pm and 0.386 nm, respectively, within the travel range of 170 nm.