Walk-off reduction, using an external optical plate and Bessel–Gaussian interaction
Mansouri Masoume, Askarbioki Mohsen, Ghavami Sabouri Saeed†, Khorsandi Alireza‡
       
Optical arrangement used to reduce the walk-off angle, employing a BK7 plate of variable thickness that can be rotated with respect to the third-harmonic (blue arrow) beam. An optical filter is used to block the fundamental beam.