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Proceedings Paper

Triangular linetype wavelength calibration process for micro-spectrometers with multichannel detectors
Author(s): Yuzhao Wang; Yinchao Zhang; Yan Wu; Siying Chen; Zongjia Qiu
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Paper Abstract

An advanced wavelength calibration process with higher wavelength accuracy is developed based on the conventional calibration method of micro-spectrometers with multichannel detectors. In the conventional method, the unit of pixel data for calibration is pixel. A pixel unit usually has a length measured in μm, and the wavelength peak is not always in the middle of a pixel. Thus, the location of a spectral line's peak can't be got accurately. The length of a pixel arouses a measurement error of wavelength-peak location. And the error of wavelength-peak location results in error of pixel wavelength calibration. A new method, applying triangular linetype to approach the real spectral linetype, which enhance the wavelength-peak location accuracy, is introduced in this article. The method is proved useful in theory and a function for calculating the accurate pixel location is produced from the method. Two steps are added to the conventional method before the final pixel-wavelength fitting. First, three-pixel data collection is carried out. In the conventional method, only the highest pixel of one spectral line is chosen for calibration, but that is not enough for getting more accurate wavelength peak location. In the new method, three pixels, including the highest one and its two neighbors, are collected for the more accurate wavelength-peak location process. Second, sub-pixel calculation is executed to enhance the peak location accuracy. On the assumption that a triangular linetype can approximately replace the real linetype in theory, the wavelength-peak location is calculated more accurately and the precision of the result is better than 0.5 pixel. When an unknown spectral line is measured, accurate wavelength-peak location can be got in the same way. The experiment was based on a compact spectrometer HR4000, with a crossed Czerny-Turner optical design, produced by Ocean Optics Company. Its manufacturer's calibration precision, which is given by the company, is 0.24nm. Mercury lamp's line spectra are used as wavelength standards. The results show that by applying the new method, the wavelength-peak location accuracy improves from 1 pixel to around 0.5 pixel, and the wavelength accuracy improves from above 0.2nm to around 0.1nm.

Paper Details

Date Published: 3 February 2009
PDF: 5 pages
Proc. SPIE 7160, 2008 International Conference on Optical Instruments and Technology: Optoelectronic Measurement Technology and Applications, 71602V (3 February 2009); doi: 10.1117/12.807823
Show Author Affiliations
Yuzhao Wang, Beijing Institute of Technology (China)
Yinchao Zhang, Beijing Institute of Technology (China)
Yan Wu, Beijing Institute of Technology (China)
Siying Chen, Beijing Institute of Technology (China)
Zongjia Qiu, Beijing Institute of Technology (China)


Published in SPIE Proceedings Vol. 7160:
2008 International Conference on Optical Instruments and Technology: Optoelectronic Measurement Technology and Applications

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