Background: The infrared beam line consists of many kinds of optical components that are susceptible to the external mechanical vibration

which will be further amplified by the long optical paths to seriously destroy the stability of infrared beam position. Purpose: The active feedback controller is used to stabilize the infrared beam position disturbed by the external environment. Methods: The design of the active feedback controller used in the infrared beam line of SSRF was proposed in this paper firstly

which included its background

light-path layout and operating process. Subsequently

the selections of the crucial components such as detector and actuator were discussed in details. Finally

the correction compensator design and its experimental test were also presented. The correction compensator design was realized by utilizing the frequency response method

and tested in time domain

frequency domain and mathematical model simulation of the controlled object. Results: The experimental tests included time domain step response signal of the controller

the time domain signal and its relevant magnitude spectrum in frequency domain due to the light source simulation vibration. Conclusion: The results show that the maximum effective operating band is 250 Hz and the maximum steady state error is 5 um.Cited