网格光栅和电子显微镜倍率的测定

Net Grating and the Testing of Magnification in the TEM

透射式电子显微镜(TEM)倍率的测量和标定是TEM的一项基本测试技术。传统的方法是用衍射光栅的刻槽间距作为基准尺寸进行测试。本文改进了以往用相衬显微术测定光栅样品间距的方法,而用普通的显微镜在掠射照明情况下测定了原刻光栅和TEM光栅复型的刻槽间距。发现了光栅常数的标称值和由干涉方法测定的刻槽间距平均值与复型样品的实测间距有较大的误差。测试结果表明,光栅刻槽间距的局部误差呈随机的高斯分布;不同方位的刻槽间距也有差异,而光栅复型样品制备时引入的变形是导致间距误差的主要因子。本文用高斯误差定律归纳了原刻光栅和光栅复型间距的大量实测数据,求得了光栅刻槽间距的最佳代表值及其或然误差,从而在一定置信水平上保证了TEM倍率测量的可靠性,其精度优于2%。不同间距的各种网格光栅(300,600,1200,2400Line/mm)已能提供实际测试。

The testing and demarcation of magnification for TEM is a fundamental testing technic in the transmission electron microscope (TEM). Tradisionally, the groove-spacing of diffraction grating is used as the standard dimension for testing of the magnification, that is measured by phase-contrast microscopy or reflective microscopy. In this paper, a new simple method by means of common microscope to test the groove-spacing of the grating and the replica in the state of grazing illumination is described. So we discovered, there are errors bewteen the characteristic value of grating-constant and testing value of the practive groovespacing average value as well as replica specimen. The testing outcome make know, the local error of groove spacing is Gauss distribution of the random. There are difference on the groove-spacing of the different point and the compass too. But deformation is a primary factor, it leads to spacer error when replica grating prepared. According to Gauss theory, we induce a vast amount of reality value(original grating and replica grating). So strive for the optimun deputation values and probability orror of the groove-spacing, thus ensured for reliability of the TEM magnification testing in the fixed believe level. It's acuracy is better than 2%, all kinds net gratings and replica of the different spacers(300, 600, Line/mm) could be purnish practice testing.