brief introduction: Continuous laser has a stable working state, that is, steady state. The number of particles at each energy level and the radiation field in the cavity are stable in the continuous laser. Its work is characterized by the excitation of the working substance and the corresponding laser output, which can continue in a continuous way over a long period of time. Solid state lasers excited by a continuous light source, gas lasers and semiconductor lasers working by a continuous electric excitation are