Research On Laser Spectrum Detection Technology Based On Static Fourier Transform Interferometer

Laser spectrum detection is an important technology which is used in laser reconnaissance, laser warning and contamination detection. The identification of the laser spectrum can provide the information for optic-electronic countermeasure and contamination detection of the air. On the basis of analysis of and research on the current laser spectrum detection technology, the paper proposed the protocol that, use fiber optical antenna and modified wedge interferometer to obtain the laser interference fringe, then the laser spectrum can be obtained in real time, by Fast Fourier Transform (FFT)of the interference fringe.At first, the theory of coherent spectrum detection and Fourier Transform spectrum detection technology were analyzed. On the basis of comparison among various spectrum detection equipments' principles and characteristics, a passive laser spectrum detection system based on modified wedge interferometer was designed. Then the parameters of the optical antenna and the interferometer were expatiated detailedly.Secondly, the principle and arithmetic of signal acquisition, filtering, laser pulse recognition, FFT and spectrum calibration were analyzed, the hardware circuit with low noise, high speed and real-time signal acquisition were designed by combining with the optical system and the signal processor. The signal processing hardware and related interface design was accomplished based on DSP.Finally, tests were carried on in the laboratory, eight kinds of laser with different wavelength(532.2nm,633nm,635.3nm,651.3nm,659.8nm,781.8nm,857.6nm,988.2nm)were used. The experiment results indicate that the response time of the designed system is less than 10ms and the wavelength resolution is less than 10nm.