Coordinate interferometric system for measuring the position of a sample with infrared telecom laser diode

Miroslava Holá; Josef Lazar; Martin Čížek; Václav Hucl; Šimon Řeřucha; Ondřej Číp

doi:10.1117/12.2257319

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11 November 2016 Coordinate interferometric system for measuring the position of a sample with infrared telecom laser diode

Miroslava Holá, Josef Lazar, Martin Čížek, Václav Hucl, Šimon Řeřucha, Ondřej Číp

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Proceedings Volume 10151, Optics and Measurement International Conference 2016; 101510X (2016) https://doi.org/10.1117/12.2257319
Event: Optics and Measurement 2016 International Conference, 2016, Liberec, Czech Republic

Abstract

We report on a design of an interferometric position measuring system for control of a sample stage in an e-beam writer with reproducibility of the position on nanometer level and resolution below nanometer. We introduced differential configuration of the interferometer where the position is measured with respect to a central reference point to eliminate deformations caused by thermal and pressure effects on the vacuum chamber. The reference is here the electron gun of the writer. The interferometer is designed to operate at infrared, telecommunication wavelength due to the risk of interference of stray light with sensitive photodetectors in the chamber. The laser source is here a narrow-linewidth DFB laser diode with electronics of our own design offering precision and stability of temperature and current, low-noise, protection from rf interference, and high-frequency modulation. Detection of the interferometric signal relies on a novel derivative technique utilizing hf frequency modulation and phase-sensitive detection.

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Miroslava Holá, Josef Lazar, Martin Čížek, Václav Hucl, Šimon Řeřucha, and Ondřej Číp "Coordinate interferometric system for measuring the position of a sample with infrared telecom laser diode", Proc. SPIE 10151, Optics and Measurement International Conference 2016, 101510X (11 November 2016); https://doi.org/10.1117/12.2257319

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