The Realization Of Fast Fourier Transform Based On FPGA In Laser Spectrum Detection

Laser spectrum detection is an important technology which is used in the domains of laser reconnaissance,laser warning and contamination detection. The identification of the arriving laser spectrum can provide a basis for optic-electronic countermeasure. On the base of studying and analyzing the current laser spectrum-determination technology, the paper uses the non-scanning M-Z interference to obtain the laser interference fringe, after making Fast Fourier Transform to the interference fringe can obtain the laser spectrum in real time.Laser interference fringes formed in M-Z interferometer is converted into time series by a CCD camera. The Fast Fourier Transform of time series can be achieved in FPGA. According to the system response time and SNR, the detector Array and parameter are chosen. The interface circuits between FPGA and camera ,and the module of data transmission,storage are also designed.In order to realize Fast Fourier Transform, the radix-2 decimation-in-time(DIT) algorithm is used. Based on the hardware of XC3S400, and software ISE8.1, by using hardware description language, the FFT module has been designed to achieve of time series of signal with 512 point and 10 bit precision. All the programs are download to the configuration chip successfully.The periphery circuits such as power supply module,display module and configure circuit have been designed. At the end of this paper, comparison of the Fast Fourier Transform result between by using FPGA module and the theoretical computation of the same interference fringe has been done , Which indicates that precision and the speed can meet the require of laser spectrum detection.