F­Theta Scanning Lenses F­Theta Scanning Lenses are commonly used in laser marking, engraving, and cutting systems. Used in conjunction with a galvanometer, beam expander, and Nd:YAG or CO2 laser source, F­theta lenses are designed to provide a flat field at the image plane of the scanning system. Our Nd:YAG F­Theta Lenses feature multiple elements for the ultimate in image resolution. An air­spaced design and high efficiency AR coatings guarantee excellent throughput and durability. An industry­standard M85 threading on all F­theta lenses allows for easy mounting and simple retrofitting of OEM systems. Our Nd:YAG F­Theta Lenses feature pulsed laser damage thresholds up to 5J/cm2 @10ns, or 1MW/cm2 (CW). For diffraction­limited focusing performance at the image plane, the entire entrance pupil of the F­Theta lens should be utilized. Our 3X and 5X TECHSPEC® Fixed Power Laser Beam Expanders are ideal complements to our F­Theta lenses.