An Intelligent Dynamic Alignment System for Interferometer of Fourier Transform Spectrometer

摘要

An intelligent dynamic alignment system for a Michelson interferometer which is applied to a Midinfrared band Fourier transform spectrometer (FTS) is presented. Three photodiodes are used to detect the tilt of moving mirror opposite to fixed mirror with the assistance of the interfered signal of a reference He-Ne laser. This technique is based on detecting the phase difference of laser signal between every two diodes in two perpendicular directions. And four magnetic actuators behind the mounting brace of fixed mirror are used to change the pose of fixed mirror. The system is controlled by a digital signal processor (DSP) in real-time. A feedback algorithm is used to tilt fixed mirror following the action of moving mirror so as to keep both mirror planes in perpendicular. Experiment result shows that the relative tilt between two reflecting mirrors can be restricted in a range no more than ±1.5*l(T6rad. This system is effective and reliable to be applied to scanning interferometer of Fourier transform spectrometer.