Uncertainty Evaluation for Frequency Calibration of Helium–Neon Laser Head Using Monte Carlo Simulation

Abstract

Helium–neon laser heads have vast applications in various advance engineering and research fields. He–Ne laser heads in conjunction with optical interferometers are also used for precise and accurate measurements of various dimensional metrology parameters. To achieve reliable measurement observations, periodic calibration of He–Ne laser heads against the primary standard of length (Iodine stabilized He–Ne laser for realization of SI unit “Metre,” wavelength 633 nm) is essential. In the present manuscript, various factors contributing in measurement errors have been recognized and evaluation of measurement uncertainty for calibration of He–Ne laser head is conducted through law of propagation of uncertainty (LPU) and Monte Carlo simulation (MCS) methods. Octave software and R programming language were used for the numerical calculations for Monte Carlo Simulation. The uncertainty values obtained through both the techniques are compared and found to be close. Using LPU, relative combined uncertainty has been ± 3.80 × 10^–10 and relative expanded uncertainty has been ± 7.61 × 10^–10 and using MCS relative combined uncertainty has been ± 3.84 × 10^–10 and expanded uncertainty has been ± 7.68 × 10^–10 obtained.