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Proceedings Paper

In-process automatic wavelength calibration for CCD-spectrometers
Author(s): J. Mirapeix; A. Cobo; A. M. Cubillas; O. M. Conde; J. M. Lopez-Higuera
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Paper Abstract

In CCD-spectrometers, the relation between the CCD-pixel number and the associated wavelength is established by means of a calibration polynomial, whose coefficients are typically obtained using a calibration lamp with known emission line wavelengths and a regression procedure. A recalculation of this polynomial has to be performed periodically, as the pixel number versus wavelength relation can change with ambient temperature variations or modifications in the optics attached to the spectrometer connector. Given that this calibration procedure has to be performed off-line, it implies a disturbance for industrial scenarios, where the monitoring setup must be altered. In this paper an automatic wavelength calibration procedure for CCD-spectrometers is proposed. It is based on a processing scheme designed for the in-process estimation of the plasma electronic temperature, where several plasma emission lines are identified for each spectral capture. This identification stage involves the determination, by means of a sub-pixel algorithm, of the central wavelength of those lines, thus allowing an on-line wavelength calibration for each single acquired spectrum. The proposed technique will be demonstrated by means of several experimental arc-welding tests.

Paper Details

Date Published: 30 April 2008
PDF: 8 pages
Proc. SPIE 7003, Optical Sensors 2008, 70031T (30 April 2008); doi: 10.1117/12.781040
Show Author Affiliations
J. Mirapeix, Univ. de Cantabria (Spain)
A. Cobo, Univ. de Cantabria (Spain)
A. M. Cubillas, Univ. de Cantabria (Spain)
O. M. Conde, Univ. de Cantabria (Spain)
J. M. Lopez-Higuera, Univ. de Cantabria (Spain)

Published in SPIE Proceedings Vol. 7003:
Optical Sensors 2008
Francis Berghmans; Patrick P. Meyrueis; Thomas P. Pearsall; Anna Grazia Mignani; Antonello Cutolo, Editor(s)

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