对显微镜分辨率的几点认识

SEVERAL UNDERSTANDINGS ABOUT MICROSCOPE'S RESOLVLNG POWER

显微镜的分辨率常用能分辩的两点之间的极限距离来衡量，该距离的值与光的波长，物镜的孔径数以及光的相干性有关。对于不相干的两个光点，分辨极限为Z=0．61入。／N·A，若两光点是相干的，则分辨极限为Z=0．77入。／N·A，考虑显微标本类似光栅结构，通常是被照明的，具有一定的相干性，着相干光垂直照射光栅，分辨极限Z=入。／N·A，若是斜照射，则Z=0．5入。／N·A后者比较更接近于显微镜的实际情况。另外，为了达到设计上的分辨距离还要有良好的照明和反衬度。

The resolving power of a microscope is usually judged by the limiting distance between two reso-lutable points. The value of this distance is releted to the wavelength of light, the aperture number of objective lens and the coherency of light. For two uncoherent light points, the resolution limit is z=0. 61λ0/N· A, while for two coherent light points, the resolution limit is z= 0. 77λ0/N· A. Con-sidering that the microspecimen is similar to the grating structure, usully lighted up and has some co-herency, so the resolution limit is z=λ0/N· A if the coherent light irratiate vertically the grating and z=0. 5λ0/N· A if in an angle. The later one is closer to the real case of a microscope. In addition, to obtain the designed resolution distance, gnd lighting and good contrast are necessary.