Getting low CO₂ Laser power is the key technology in laser-assisted microvascular anastomosis. The technology which is used to get low CO₂ Laser power from the general CO₂ Laser is presented in this paper. Its main advantages are that Laser power on Laser scalper is modifiable, spot size is controllable and energy density on the light spot is uniform. We give the design principle and an example for practical design in this paper.