In marking system, laser beam will deflect off-axis after passing through the focusing lens system, and abnormal image or distortion will appear on the marking surface relative to the ideal plane. Flat-field focusing lens, also known as field scanning lens, f-theta lens, is a professional optical system, which is designed to make laser beam in the whole marking plane form a uniform size of focus spot, it is one of the most important parts of laser marking machine. Field lenses can be divided into f-theta lenses and telecentric lenses.
