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Proceedings Paper

Precision displacement measurement using a modulating ESPI
Author(s): Seong Jong Kim; Young June Kang; Dong Pyo Hong; Kyung Suk Kim; Nak Kyu Park; Weon Jae Ryu; Man Young Choi
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Paper Abstract

Laser interferometry is widely used as a measuring system in many fields because of its high resolution and ability to measure a broad area in real-time all at once. In conventional LASER interferometry, for example Out-of-plane ESPI(Electronic Speckle Pattern Interferometry), In plane ESPI, Shearography and Holography, it uses PZT or other components as a phase shift instrumentation to extract 3D deformation data, vibration mode and others. However, in most cases PZT has some disadvantages, which include non-linear errors and limited time of use. In the present study, a new type of LASER interferometry using a laser diode is proposed. Using LASER Diode Sinusoidal Phase Modulating (LD-SPM) interferometry, the phase modulation can directly modulated by controlling the LASER Diode injection current thereby eliminating the need for PZT and its components. This makes the interferometry more compact. This paper reports on a new approach to the LD Modulating interferometry that involves four-bucket phase shift method. This study proposes a four-bucket phase mapping algorithm, which developed to have a guaranteed application, to stabilize the system in the field and to be a user-friendly GUI. In this paper, LD modulating interferometry had shown the theory for LD wavelength modulation and sinusoidal phase modulation. Four-bucket phase mapping algorithm then introduced.

Paper Details

Date Published: 8 October 2007
PDF: 10 pages
Proc. SPIE 6719, Optomechatronic Systems Control III, 671908 (8 October 2007); doi: 10.1117/12.754586
Show Author Affiliations
Seong Jong Kim, Chon-buk National Univ. (South Korea)
Young June Kang, Chon-buk National Univ. (South Korea)
Dong Pyo Hong, Chon-buk National Univ. (South Korea)
Kyung Suk Kim, ChoSun Univ. (South Korea)
Nak Kyu Park, Chon-buk National Univ. (South Korea)
Weon Jae Ryu, Chon-buk National Univ. (South Korea)
Man Young Choi, Korea Research Institute of Standards and Science (South Korea)


Published in SPIE Proceedings Vol. 6719:
Optomechatronic Systems Control III

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