Aiming to the accuracy output laser power control of RF excited CO2 laser. A pulse width laser power modulating unit and corresponding experiments was studied. Hardware circuit based on TMS320F2812 microprocessor and software program based on CCS3.1 platform was designed. On condition of given working mode of the laser and laser power, when real laser power was detected as the feedback, appropriate ignition pulse, maintenance pulse, continuous working mode modulating pulse, pulse working mode modulating pulse was given to realize a loop control system for laser power. When the pulse width modulator was used to modulate the laser power, the modulating frequency can be modulated in the range of 5 Hz~5 KHz if the laser was working in pulse mode. And the laser power can be modulated in the range of 5%~95% of the maximum value at any mode with the fluctuate accuracy within ±2%.
Aiming to the special high power CO<sub>2</sub> laser surface treatment, the paper developed the integrated control system based
on S7-200 PLC of transverse flow CO<sub>2</sub> laser. The selection of key technology and components, detection and control of
signals, integrated control of complete circuit, technology of human machine interface and process control of system
have been researched. Double closed loop power control system was realized, so that the stability of the laser power was
in ±2%. Also, the giving power can be controlled by the laser controller or by the processing machine, thus, the users
can control the laser more efficiently when processing. A series of experiments have been performed on 5kW transverse
flow CO<sub>2</sub> laser, the output laser power was stable at discharge current of 9A for 8 hours, and the maximal power was
5.42 kW. The new type of transverse flow CO<sub>2</sub> Laser with Integrated Control System has been applied for special laser
cladding with power-modulating on the metallic surface of the oil industry production.
Aiming at the 3kW transverse flow CO<sub>2</sub> laser, a hybrid power system and its compatibility with pin-to-flat discharge
structure has been studied in the paper, CW/pulse output laser has been obtained. The DC high voltage output consists of
switching power supply and main transformer, and three-phase SCR power supply is replaced by switching power
supply. The pulse parameters are frequency from 0Hz to 1kHz, duty ratio from 0% to 100%. The pulse waveform of
discharge voltage and discharge current are measured. The results show that row resistances have been moved, pin
resistances have been reduced to 10kΩ. When the pressure P is 8.45kPa, the highest efficiency of electric-photo
conversion of laser is up to 14.8%.The laser output power can be modulated in the state of continuous and pulse at
arrange of 3kW. Then particular laser cladding is performed on the airplane engine blade, the laser cladding crack
produced in continuous state is solved, and the heat-affected zone of laser cladding is also narrowed.