Strong-focusing optical system used for composite machining of laser turning and grinding and machining method

The invention provides a strong-focusing optical system used for composite machining of laser turning and grinding and a machining method. The strong-focusing optical system comprises a collimating system and a focusing system and is characterized in that the collimating system is composed of three spherical mirrors; the focusing system is a round light spot focusing system composed of three spherical mirrors or a linear light spot focusing system composed of one cylindrical mirror and two spherical mirrors. A single beam of laser emitted by a laser device is focused into a round light spot through the strong-focusing optical system to irradiate the surface of a rotating workpiece, the workpiece rotates according to the specified rotating speed, the laser beam scans in the axial direction according to the specified speed, light energy of the laser beam is converted into heat energy, materials in a focus area on the workpiece are melted, gasified and thrown out, and a shaft part is machined in a turning manner. In order to increase the machining speed and improve the machining precision and the surface quality, the single beam of pulse laser emitted by the laser device is converted into a linear light spot to irradiate the surface of the turned workpiece in a focusing manner, and therefore ultrathin laser grinding is achieved.