Development and calibration of a broadband extreme ultraviolet-vacuum ultraviolet spectrometer

The precise spectral characterization of laser-produced plasma extreme ultraviolet (LPP-EUV) sources, across both the in-band (13.5 nm ± 1% bandwidth) and out-of-band regions, serves as the foundation for studying conversion efficiency and spectral purity. This characterization is crucial for optimizing EUV source performance. In this paper, a broadband EUV-vacuum ultraviolet spectrometer covering the spectral range of 5-200 nm was developed, and its wavelength and relative sensitivity were calibrated using a synchrotron radiation source. A comparative analysis of different polynomial fitting orders was conducted to establish a high-precision wavelength calibration curve, providing guidelines for selecting the optimal method for different calibration scenarios. To address calibration errors caused by the charge-coupled device smear effect during sensitivity calibration, a dynamic matrix smear removal algorithm based on real-time source fluctuation correction was proposed. This optimization reduced the uncertainty introduced by the smear effect, and piecewise relative sensitivity calibration curves were established. A comprehensive uncertainty evaluation of the entire calibration process was performed. The results show that the wavelength calibration standard uncertainty is 0.0129 nm at 13 nm, and the relative standard uncertainty of the relative sensitivity calibration is 5.22% at 13 nm. The calibration accuracy reached an advanced level in the industry.