Deterministic fabrication of freeform optics using direct femtosecond laser figuring.

We demonstrate fabrication of freeform optical surfaces in glass using direct femtosecond laser figuring and finishing. The method uses an experimentally characterized and numerically optimized point influence function to model the surface response. Iterative scan path deconvolution is used to generate fabrication trajectories for target geometries and enables offline optimization. Freeform surfaces defined by Zernike polynomials were fabricated on borosilicate glass with a root-mean-squared surface figure error of 1.0 nm. The predicted surface profiles show close agreement with experimental measurements. The process is implemented as a direct, non-contact fabrication approach without post-polishing.