The purpose of the planar lens is to form a uniformly sized focused spot of the laser beam in the entire marking plane. It is one of the most important accessories of the laser marking machine.
Due to the high cost and expense of telecentric lenses, F-theta lenses are mainly used in laser marking machines for industrial applications. In the absence of deformation, the position of the focus point depends on the focal length of the lens and the tangent of the deflection angle. The position of the focus point only depends on the focal length and deflection angle, which simplifies the calculation method of focus positioning.
| Model | FT-35 | FT-78 | FT-150 |
| Focal Length（mm） | 35 | 78 | 150 |
| Entrance Pupil Diameter（mm） | 8 | 8 | 8 |
| Working Distance（mm） | 15 | 90 | 180 |
| Optical Field of View | ±17 | ±14.5 | ±15 |
| Support Image Size（mm） | F21 | F40 | F80 |
| Image F Value | 5 | 11 | 21 |
| Telecentricity | <0.3 | <0.3 | <0.05 |
| Distortion（f-tan（θ）） | <2% | <2% | <0.01% |
| Distortion（f-θ） | <1% | <0.2% | <2% |
| Support Band（nm） | 800-1600 | 800-1600 | 800-1600 |
| Total Lens Length（mm） | 45 | 45 | 82 |
Telecentric lenses are specially designed to make the chief ray of the focused beam perpendicular to the focal plane at any field of view by placing the entrance pupil of the system at the front focus position of the lens system.
F-Theta scanning lenses are commonly used in laser scanning systems that use a two-axis galvanometer to scan a designated area but cannot tolerate angles in the image plane.
By introducing a specific amount of barrel distortion into the scan lens, F-Theta scan lenses are ideal for applications that require a flat field of view in the image plane, such as laser scanning, marking, engraving and cutting systems.
Depending on the requirements of the application, these diffraction-limited lens systems can be optimized for wavelength, spot size, and focal length while maintaining distortion below 0.25% throughout the lens’ field of view.
In addition to these standard designs, BOTE OPTICS can develop complete systems for you, using components from laser beam shaping to laser beam expansion and splitting.