推导了相干照明下衍射受限螺旋相衬成像系统的成像公式，总结了影响螺旋相衬法成像效果的螺旋相位板参数，包括中心尺寸、整体尺寸以及台阶数。详细研究了各参数对螺旋相衬成像系统性能的影响，提出了各参数的合理取值范围，并通过实验验证了其正确性。所采用的计算方法，不仅可以用于研究螺旋相位板的设计，而且对于其他空间滤波器的设计同样具有参考价值。

The imaging law of diffraction-limited spiral phase contrast microscope under coherent illumination condition is derived. Three parameters of spiral phase plate that influence the imaging quality, i.e., central size, size and step number, are pointed out. Exhaustive investigations into the influences of the three parameters on the imaging results are made, and their reasonable values are presented. The validity is confirmed by experiments. This method is useful in designing the spiral phase plate. Moreover, it is also valid for designing the filters based on spatial filtering.