The focus tracking system generally consists of a focus cutting head and a tracking sensor system. The cutting head is composed of light focusing, water cooling, blowing, and mechanical adjustment; The sensor consists of sensing elements and amplification control components. According to the different sensor components, the tracking system is completely different, and there are mainly two forms of tracking systems. One is a capacitive sensor tracking system, also known as a non-contact tracking system. Another type is an inductive sensor tracking system, also known as a contact tracking system.