Since the coherent noise affected the quality of the Fizeau's interferograms in the large aperture, the coherence of the beam was changed by rotated diffuser to reduce the noise of the interfering system. The relation-ships among the speed of the rotated diffuser, the contrast of the fringes and the SNR of the system were simulat-ed. Then, the control parameters of rotated diffuser would be required in the optimum interference fringe. The inter-ference images were obtained under different control parameters, and the fringe contrast and system SNR of each image were analyzed. The results showed that the contrast can be reduced by increasing the speed of the rotated diffuser in a certain extent, but the SNR can be improved effectively and it was convenient to process the interfer-ence image later.%针对大平面菲索干涉图像的相干噪声问题,采用旋转毛玻璃片的方法改变光束的相干性,来降低干涉系统的噪声.通过对毛玻璃的转速与条纹对比度和系统信噪比之间的关系进行仿真,获得最佳干涉条纹状态所需要的毛玻璃控制参数.在不同控制参数下获取干涉图像,并分别对各图像的条纹对比度和系统信噪比进行分析.研究结果表明,增加的毛玻璃转速,虽然在一定程度上降低了干涉图像的对比度,但却有效地提高了信噪比,便于后续的干涉图像处理.
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