F-Theta Lenses

F-theta scanning lenses, sometimes referred to as simply F-Theta Lenses, are a form of scanning lens technology. Scanning lenses are useful because they allow us to focus on a spot and form localized images in a flat plane such as a piece of metal or plastic. F-theta lenses in particular work to form these precise spots by having the position of the spot location proportional to the lens's focal length and beam angle, or theta, as it enters the lens. The "f" in "focal length" and "theta" of the beam is where the term "f-theta" comes from.

Uses and Types

F-theta lenses are used most often in laser marking, cutting, and engraving systems and industries. It is also used in plastic welding, drilling of plastics and ceramics, fine cutting of materials, and even cleaning for restoration or treatment purposes. The price of one lens runs on average anywhere from $500 to just over $1000! This may seem steep, but it is worth it for the precision and high performance this lens has been engineered to achieve.

Users of f-theta lenses can choose which lens will be best for their needs by utilizing information on parameters of operating wavelength, spot size, and the scan field diameter. Additionally, field distortion and curvature should be taken into account. Once these parameters are taken into consideration, it can then be decided if the F-theta lens will be single or multi-element.

F-theta lenses can also be constructed in forms that are telecentric or non-telecentric. In general, telecentric lenses often are more multi-element than non-telecentric lenses. Earlier, uses of f-theta lenses were mentioned. Telecentric lenses are used when consistency and perpendicularity are most important. Telecentric lenses are ideal in applications such as cutting and micromachining. Non-telecentric lenses are good for engraving, product identification, and other similar processes.