Abstract: To deal with the problem of large signal noise interference in traditional Fourier transform infrared spectrometer leading to the performance degradation of the instrument, a Fourier transform infrared spectroscopy processing method based on Butterworth band-pass filter is proposed. Firstly, the transfer function of the band-pass filter circuit was deduced theoretically. Then combined with the spectrometer parameters, the specific values of the circuit components were determined by simulation using circuit software Multisim, and further optimized through experiments until the design requirements were met. Finally, the designed band-pass filter was used in spectrometer, and the signal-to-noise ratio of the instrument measured before and after adding the filter board was compared and analyzed. The experimental results show that the instrument signal-to-noise ratio obtained by the infrared spectral processing method based on Butterworth filter in the band of 2100∼2200 cm−1 and 2500∼2600 cm−1 is 1.83 and 1.96 times of that obtained by the traditional processing method without filter, respectively. It is believed that the proposed method effectively improves the signal-to-noise ratio of the instrument and the performance index of the instrument.

Key words: spectroscopy, Fourier transform infrared spectroscopy, Butterworth bandpass filter; amplitude-frequency characteristic, signal to noise ratio