Short pulse lasers offer a number of advantages in high-precision machining including a reduced heat-affected zone (HAZ) resulting in little or no additional post processing clean-up work. For X-Y scanning systems, this requires specially designed F theta lens.  The presentation will  cover F theta lens specifications; non and telecentric lens, multispectral F theta lens, the issue of back reflections and internal ghosts when using high power and short pulse lasers, how to calculate spot size relative to input beam diameters, scan field size, mirror spacing, correction files, laser M2 values relative to spot performance, thermal focus shift, anti-reflective coatings and ultra short pulse laser F theta lens color correction.