Picometer mechanical displacement measurement using heterodyne interferometer with phase-locked loop

Masato Aketagawa,Thanh Dong Nguyen,H Michinel,M.F Costa,O Frazao

doi:10.1051/epjconf/202023806003

Masato Aketagawa, Thanh Dong Nguyen + Show 3 more

Open Access

https://doi.org/10.1051/epjconf/202023806003

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Abstract

In this paper, we show picometer-order mechnical displacmment measurements using a heterodyne interferometer with a phase-locked loop (PLL). A heterodyne light source for the interferometer is implemented with a frequency stabilized HeNe laser and two acousto-optic modulators. A real time phase measurement is performed by the PLL, whose software is programmed in a field-programmable gate array (FPGA). A stiff parallel spring stage combined with a high-voltage piezoelectric actuator is used to generate picometer-order mechanical motion. With the above implementations, mechanical displacement of 10 picometer or less can be measured.

Highlights

With the rapid progress of ultraprecision engineering and semiconductor manufacturing, precise metrology systems based on laser interferometers with resolution of 10 picometer order have become necessary for displacement/distance measurements [1]
We show picometer-order mechnical displacmment measurements using a heterodyne interferometer with a phase-locked loop (PLL)
A heterodyne light source for the interferometer is implemented with a frequency stabilized HeNe laser and two acousto-optic modulators (AOMs)

Summary

Introduction

With the rapid progress of ultraprecision engineering and semiconductor manufacturing, precise metrology systems based on laser interferometers with resolution of 10 picometer order have become necessary for displacement/distance measurements [1]. Displacement-measuring heterodyne interferometers have become suitable for industrial applications [2], because they have traceability to the standard definition of the meter if frequencies of light sources are stable. We show picometer-order mechnical displacmment measurements using a heterodyne interferometer with a phase-locked loop (PLL).

Results

Conclusion