微小尺寸的测量多采用大琅和费衍射法测量，因为其衍射暗纹间距与被测尺寸之间具有很简单的线性关系．实用中，夫琅和费衍射占用空间很大．而且衍射图象与传感器尺寸很难匹配。通过对菲涅尔衍射和夫琅和费衍射光强分布的深入研究，发现二者暗纹分布是相同的．本项研究将衍射测量扩展到菲涅尔衍射区，不但可以扩展测量范围，还可以通过扩大所接受衍射谱级次的方法，提高测量精度，具有较高的实用价值，理论上也有一定突破。 The measurement of the small size is mostly measured by the Grandfather diffraction method because of the simple linear relationship between the diffraction obscure pitch and the measured size. In practice, Fraunhofer diffraction takes up a lot of space. Diffractive images and sensor size and difficult to match. Through in-depth study of the Fresnel diffraction and Fraunhofer diffraction intensity distribution, it is found that the distribution of obscurations is the same. This study extends the diffraction measurement to the Fresnel diffraction region, not only to expand the measurement range, but also to improve the measurement accuracy by expanding the order of diffraction orders received, which has high practical value and a certain theoretical breakthrough.