An optimization method of S-curve intensity control model was propoded for further im provement of joint quality during laster direct writing.On the basis of analyzing the effect of the Scurve parameter varation on the joint quality,the optimized interrelationship of the radian and the radius R used in the control model was established consdering in to be optimial when the exposure does distribution gor an extremum at one point. The joint length after optimization can be simply determined by the radian Φ，and is just twice as long as that of using slope-line control method.The experimental results are consistent with the theoretical analysis，and indicate that the proposed optimization method can further increase the valid transition area length and can reduce the variation rate of exposure dose distribution at the joint area.Therefore the proposed method improves the joint quality as well as guarantees the writing efficiency.作者简介：TAN Jiu-bin received his MS and PhD degrees in the Department of Precision Instruments,Harbin Institute of Technology,in 1987 and 1991,respectively.Currently,he is the director of Institute of Ultra-precision Optoelectronic Instrument Engineering,Harbin Institute of Technology,the vice director of Chinese Society for Measurement(CSM),and the director of China Instrument Society (CIS).He is well known in the field of ultraprecision optical,electrical,and mechanical technology and instrument engineering.E-mail:jbtan@hit.edu.cn