在计量光学仪器中读数镜头(即分划刻度尺)的放大倍数应与物镜(即主刻度尺)的放大倍数相一致,即当物镜对焦在按毫米分度的主刻度尺上时,任1毫米尺寸的两刻线的影象应分别与按0.1毫米分度的读数镜头中的第一对和第十一对双线中心相重合。但是在事实上不可能做到,因此仪器技术条件和检定规程中都给出允许偏差的数值,很明 The magnification of the reading lens (ie the division scale) in the metrology optics shall be in accordance with the magnification of the objective (ie the main scale), ie when the objective is focused on the main scale in millimeters, either Millimeter-sized images of the two scribe lines shall coincide with the first and eleventh pairs of two-line centers in a reading lens graduated by 0.1 mm, respectively. But in fact impossible to do, so the instrument technical conditions and test procedures are given allowable deviation of the value, it is clear