为了提高干涉检测精度，必须抑制系统的相干噪声。根据统计光学建立了带环形光源干涉仪系统信噪比的理论模型，分析了环形光源参数、光场相干面积与系统信噪比之间的关系，以提高信噪比为目标，优化设计并采用计算全息方法控制环形光源的参数。分析结果表明，光场的相干面积与环形光源面积成反比，系统的信噪比主要由环形光源面积决定，面积相等时环形光源抑制相干噪声的效果优于圆形空间扩展光源；环形光源的参数由锥形波前的空间频谱宽度、毛玻璃与焦平面间的距离和计算全息图的空间载波频率控制。传统点光源和环形光源的对比实验表明，环形光源有效地抑制了相干噪声，将系统的平均信噪比从点光源的5.2 dB提高到8.6 dB.

To improve measurement accuracy, the coherent noise of interferometric system should be reduced effectively. A theoretical model of signal-to-noise ratio (SNR) in interferometric system with ring source is proposed by means of statistical optics. The relations among parameters of ring source, coherent area of optical field and SNR of system are analyzed. By maximizing the objective function of SNR, optimization is employed to ring source and then the optimized parameters are controlled by computer generated holography. According to the theoretical model, the SNR of a given system depends on area of ring source, which is inverse proportion to coherent area of optical field. The parameters of ring source can be controlled by spectral width of conical wavefront, distance between rotating diffuser and focal plane, and spatial carrier frequency of computer generated hologram (CGH). Experimental comparison between point source and ring source shows that the average SNR of system increases from 5.2 dB to 8.6 dB by utilizing ring source.