F-θ lens design for high-precision semiconductor laser marking machine

In order to ensure the scanning quality of F-θ lens for semiconductor laser marking machine and realize the linear change of the image height and the scanning angle, it is necessary to give a certain distortion to the F-θ lens and satisfy the isoplanatic condition. Firstly, the working principle and aberration requirements of the F-θ lens were analyzed, and the appropriate glass material was selected by the light source imaging requirements of 1 064 nm semiconductor laser marking machine to reasonably distribute the focal power of each lens to ensure the isoplanatic imaging. Secondly, according to the linear imaging requirements of F-θ lens, the total distortion of the system was 1.6%, which was the sum of the actual barrel distortion and the relative distortion. Finally, in the optimization design of the optical system, these two optimal parameters were introduced to observe the system imaging changes during the optimization process. The design results show that the system modulation transfer function (MTF) curve is closed to the diffraction limit, the relative distortion of the F-θ lens is less than 0.36%, the root-mean-square (RMS) radius of each field of view (FOV) is smaller than the Airy disk diameter, and 70% energy of the whole system is concentrated in a circle with a diameter of 16 μm, the total distortion of the system is 1.58%, which meets the requirements of design index.