Improving the control performance of frequency stabilized system for transverse Zeeman laser tube

A real industry scale frequency stabilized system for transverse Zeeman laser tube is composed.It is based on 8098 single chip computer system,which calculates control voltage with MPC algorithm and outputs PWM wave to realize thermal compensation.Because the control voltage calculated from MPC algorithm is always real number,it must be rounded to integer.This round error can influence the control performance seriously.A method of improving D/A converting precision by modulating pulse width of PWM wave with low frequency and little amplitude is introduced.The experiment show that it is effctive.By adopting this method,control range is enlarged,so that the system can be stabilized over longer period than 10h.The laser tube reached frequency stability of 8.7×10-10 with sample time period of 10s.