Simultaneous laser vibrometry on multiple surfaces with a single beam system using range-resolved interferometry

Thomas Kissinger; Thomas O.  H. Charrett; Stephen W. James; Alvin Adams; Andrew Twin; Ralph P. Tatam

doi:10.1117/12.2183281

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22 June 2015 Simultaneous laser vibrometry on multiple surfaces with a single beam system using range-resolved interferometry

Thomas Kissinger, Thomas O. H. Charrett, Stephen W. James, Alvin Adams, Andrew Twin, Ralph P. Tatam

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Proceedings Volume 9525, Optical Measurement Systems for Industrial Inspection IX; 952520 (2015) https://doi.org/10.1117/12.2183281
Event: SPIE Optical Metrology, 2015, Munich, Germany

Abstract

A novel range-resolved interferometric signal processing technique that uses sinusoidal optical frequency modulation is applied to multi-surface vibrometry, demonstrating simultaneous optical measurements of vibrations on two surfaces using a single, collimated laser beam, with a minimum permissible distance of 3.5 cm between surfaces. The current system, using a cost-effective laser diode and a fibre-coupled, downlead insensitive setup, allows an interferometric fringe rate of up to 180 kHz to be resolved with typical displacement noise levels of 8 pm Hz^-0.5. In this paper, the system is applied to vibrometry measurements of a table-top cryostat, with concurrent measurements of the optical widow and the sample holder inside. This allows the separation of common-mode vibrations of the whole cryostat from differential vibrations between the window and the sample holder.

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Thomas Kissinger, Thomas O. H. Charrett, Stephen W. James, Alvin Adams, Andrew Twin, and Ralph P. Tatam "Simultaneous laser vibrometry on multiple surfaces with a single beam system using range-resolved interferometry", Proc. SPIE 9525, Optical Measurement Systems for Industrial Inspection IX, 952520 (22 June 2015); https://doi.org/10.1117/12.2183281

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