Improved Wavelength Calibration by Modeling the Spectrometer.

Area of Science:

• Spectroscopy
• Optical Engineering
• Metrology

Background:

• Wavelength calibration is crucial for spectroscopic applications.
• Traditional methods use polynomial fitting to spectral lines from reference lamps.
• Existing methods lack accuracy for spectral regions beyond reference line coverage.

Purpose of the Study:

• To develop a fast and robust wavelength calibration routine for spectrometers.
• To improve accuracy, especially in spectral regions outside reference lamp lines.
• To introduce novel methods for evaluating wavelength calibration accuracy.

Main Methods:

• Developed a calibration routine based on physical modeling of the spectrometer's optical system.
• Tested the algorithm on both reflection and transmission spectrometers.
• Introduced new evaluation metrics for wavelength accuracy.

Main Results:

• Achieved accuracy comparable to second- and third-order polynomial fitting within reference line ranges.
• Demonstrated 12-121 times greater accuracy than third-order fitting and 2.5-6 times greater accuracy than second-order fitting for spectral bands outside reference lines.
• The physical modeling approach searched more parameters in less time, yielding superior accuracy.

Conclusions:

• The proposed physical modeling method provides a fast, robust, and highly accurate wavelength calibration solution.
• This approach significantly enhances accuracy for spectral regions beyond the reach of traditional reference lamps.
• New evaluation methods offer superior assessment of wavelength calibration performance.