1. What Is an F-Theta Lens?
An F-Theta lens, also called a scan lens or flat-field focusing lens, focuses the laser beam across a flat working field in a Galvo system.
2. Mechanical Factors
A typical optical path includes:Laser Source → Beam Expander → Galvo Scanner → F-Theta Lens → Workpiece.
The F-Theta design creates an approximately linear relationship between the Galvo scan angle and the Laser spot position on the working plane.
3. How Does Focal Length Affect the Image?
Shorter focal lengths are often suitable for smaller working areas and fine detail, while longer focal lengths are generally used for larger scan fields. Do not select a lens based on focal length alone; consider the working area, laser spot size, required accuracy, and working distance.
4. Laser Wavelength
Fiber, Green, UV, and CO₂ systems use different wavelength ranges. The lens must have the correct material and coating for the Laser Source wavelength.
5. Check Beam Diameter and Galvo
compare reflect path lens beam, aperture level Galvo, entrance pupil and beam expander. Beam not suitable has align cause clipping and image affect function mass transmit through.
6. Telecentric and Non-Telecentric
Non-telecentric lenses are widely used for marking and engraving. Telecentric designs keep the beam closer to perpendicular across more of the working area and can be suitable for applications requiring higher geometric accuracy.
7. Working Distance
Check the working distance, lens-to-workpiece distance, installation space, product height, and fixture structure.
8. Information to Check When Purchasing or Replacing a Lens
- Laser type and wavelength.
- Laser power.
- size area working.
- Galvo scanner model and aperture.
- Beam Diameter.
- target focus current at.
- Working Distance.
- type fixture mechanical air.
- request processing.
Conclusion
Select the F-Theta Lens according to the optical-system configuration and application requirements.
Do not select a lens simply because the size appears similar. Compare the wavelength, focal length, scan field, beam diameter, Galvo scanner, working distance, laser power, coating, and fixture type.