Every time the laser contacts a new device or conducts a new experiment, the first step must be focusing. Only when you find the focal plane, can you correctly determine other process parameters, such as defocusing amount, power, speed, etc. In the field debugging, the first thing is to fix the focus. If the focus is not right, it will directly lead to subsequent defects. The direction of improvement is impossible to talk about, or even to the wrong direction. Therefore, finding the focal plane is the first priority of process debugging, proofing and experiment.