F-theta lens

F-Theta Lens are commonly used in conjunction with laser scanner head in laser engraving, cutting, and marking systems. F-theta lens can make laser beam unifrom and focus due to the radial image height equals to focal length of the lens multiplied by the angle of the chief ray makes in the object space. Typically the F theta distortion of this lens is kept less than 1% so that it produces a precise spot on the flat field on image plane.

F-theta lens — List page from Classic Sites