F-theta lenses are designed to provide flat field on the image plane for scanning and engraving applications where a high power laser and set of rotating mirrors are used to scan across a given field.
EKSMA Optics offers F-Theta Scanning Lenses of 90 mm and 104 mm diameter. F-Theta lenses are designed for Nd:YAG laser first (1064 nm), second (532 nm) and third (355 nm) harmonics.