MC GratingStochastic C-method
A convergence aid for deep smooth profiles, new in the 2026-05-25 release of the three Chandezon codes.
What it does
The C method converges more slowly for deep gratings. The 2026-05-25 release adds an option, in the Settings dialog of the Chandezon codes, that follows a 2024 paper by J. Chandezon and G. Granet [26], “Diffraction by gratings: from the C-method to the stochastic C-method”, J. Opt. Soc. Am. A 41, 1675 (doi:10.1364/JOSAA.530262): a small random Brownian noise is added to the grating profile, which can sometimes improve convergence.
The trade-off, in the changelog's own words
Added option for Stochastic C-method according to JOSA A v.41 (9), p.1675 (2024). Thanks to Dr. J. Chandezon. Adding a small random Brownian noise to the grating profile can sometimes improve the convergence of the C-method for large grating depths, however the results with it applied are not exactly repeatable.
For a result that must be reproducible to the last digit, leave it off.
Where it lives
In the same release the C-method code was refactored and the Settings dialog modified; the option is available in Chandezon Collinear, Chandezon Conical and Chandezon Crossed. The in-application help (last revised in 2018) does not describe it yet; the changelog entry is the reference, and the Settings dialog topic covers the rest of the dialog.