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In order to clearly reconstruct targets in a dim and deep space under the condition of the Lower Signal to Noise(SNR),a new time domain signal acquisition method of Fourier Telescopy(FT) based on Non-uniform Periodic Sampling(NUPS) was proposed.The simulation experiments on the proposed method were performed and the reconstructed images by NUPS method and traditional uniform sample method were compared.With the NUPS method,100 points were respectively collected at the sampling frequency 1 MHz and 5 MHz.Then the signals of two sequences were respectively fast Fourier transformed and the concern frequency information was averaged.With traditional uniform sampling methods,200 points were collected at 1 MHz and 5 MHz sampling frequency and then demodulated average was developed.Compared results show that the Strehl ratio of reconstructed image with diffraction-limited image is enhanced 0.03 compared to the original method when SNR is 50,and the Strehl ratio is 0.531 1 that is improved 0.223 3 compared with uniform sampling when SNR is 20.Obviously,imaging quality is improved by the NUPS method under conditions of low SNRs,thus the laser power is reduced.The NUPS lays the technical foundation for the implementation of the FT engineering system.

In order to settle the problem of high power short pulse laser of Fourier telescope including part period of signal,the technique of multiple pulse segment was first put forward and its basic principle and application was also first studied.Firstly,the conflict between high power short pulse laser and band width of acousto-optic frequency shifter was introduced,and then the difficulty that part period signal was demodulated by conventional time demodulation formula of Fourier telescope was put forward.Secondly,the basic principle of multiple pulse segment was given and the condition of segment between shifting frequency,pulse repetition and pulse width under ideal instance was deduced.Thirdly,the effects of stabilization of frequency shifting and pulse repetition on imaging results of multiple pulse segment were analyzed and the effects of changing pulse width on imaging results of multiple pulse segment under usual condition were studied by computer simulation.At last,the conclusion was acquired that shifting frequency and pulse repetition had no effects on imaging and the figure of object could also been identified under the condition of laser pulse changing less than 25%.

To improve the imaging quality of a Fourier Telescopy(FT) and to implement the high-resolution imaging for moving targets,the data processing methods to inhibit the spectral leakage generated by the frequency shift error from an acousto-optic frequency shifter,the bias of an optical device and truncating signals were researched and how to calculate the signal frequency in real time was given.Firstly,an all phase spectrum analysis technology was used to process sampling signals of a static target and a search algorithm was taken to capture the maximum frequency value of each interferometric beam.Then,the actual frequencies of any two beams were calculated by an all phase time shift phase difference correcting spectrum method.Finally,the frequency deviation and demodulated target's Fourier information were obtained and the demodulation frequency of the non-whole point was estimated by the least square fitting.The results show that the Strehl ratio of reconstructed image by proposed method is increased by 3% as compared with that of traditional methods.Furthermore,the new method has a higher inhibiting ability for spectral leakage,better reconstructed image,and it can provide the reference for data processing of moving targets.