Laser Scanning Lenses
Most lenses have a field position defined by the product of the focal length, F and the tangent of the field angle, theta. This is not a favorable relationship for focused spots that are uniformly spaced as a function of angle. A form is preferred that corrects this problem for such applications as laser marking and engraving engines, laser writers, true laser printers, and laser machining or pattern generators. That form is referred to as an F-Theta lens, for it removes the dependency of spot location on the tangent of the angle, and causes it to be dependent simply on the angle.
SMA has a long experience with F-theta scan lenses, and has developed software to properly define the number of facets and scan angle required on a polygon scanner in order to achieve the necessary resolution and coverage for any given marking or writing application for an F-theta lens of a given focal length and F-number.
These F-theta lens designs have incorporated anamorphic elements in order to achieve exceedingly small spot sizes over a long scan length.