大量的测量问题,其中包括对毛细管、光纤材料几何参数的检测,以及对用于激光器、电子和气体放电装置的腔型介质管,也即直径比照射波长要大的圆柱体的测试,都不可能采用衍射法来解决。后者要有远区条件来保证,因而只有借助复杂的准直装置才得以实现。但这些装置会使测量复杂,而且还会带来较大的 A large number of measurement problems, including the testing of capillary, optical fiber geometry, and the testing of cavity-type dielectric tubes for laser, electronic and gas discharge devices, ie cylinders with larger diameters than the irradiation wavelength, Diffraction may be used to solve. The latter must be far-field conditions to ensure that only with the help of complex collimation device was achieved. However, these devices can make measurements more complex and can lead to larger ones