The optical processor of SAR requires a set of precise control system for the film transport to obtain high dynamic resolution. The control system ensures a stabibized and synchronous motion of the data film and image film. We have developed a film velocity and tension control system

which controls film velocity using phase-lock loop with the complex control

and drives two set of film transport with a high stabilized pluse generator

so that the tracking error between the data film velocity and image film velocity is less than 0.3%. The film tension control system

which uses position sensor of opto-electric potentiometer

makes the variance of tension in full velocity range less than 6.8g. This paper describes the operation principle

main performance and measured results of the control system.