① Pillow or barrel distortion is an inherent phenomenon of galvanometer marking, which is determined by the scanning mode of galvanometer. The solution is to correct the distortion;
② There are two methods of correction. One is hardware correction, which is rarely used at present. The other is software correction, which is the one we use more at present;
③ The method of hardware correction is to change the voltage value of the analog signal output by the D/A card according to a certain rule through a correction card, and then transmit the signal to the galvanometer;
④ The method of software correction is that the marking software itself has a correction function. During the marking process, the digital signal is processed according to a certain method, and then the signal is transmitted to the D/A card.