A signal-noise ratio (SNR) testset for image intensifiers is reconstructed. The signal processing module, computer module and measurement software of testset are redeveloped. The frequency spectrum measurement of noise of image intensifiers is achieved by integrating fast Fouier transform (FFT) with hardware filter and infinite impulse response digital filter (IIR DF). The improved testset is used to analyze frequency spectra of noise of image intensifiers. The results are given and analyzed. The measurement method of SNR is discussed basing on the obtained frequency spectra of noise.© (2003) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.