A system of fine lines dots cross hairs or wires in the focal plane of the eyepiece of an optical instrument.

光学仪器的目镜上的细线、圆点、十字型细线或金属丝组成的系统。

youdao

A system of fine lines dots cross hairs or wires in the focal plane of the eyepiece of an optical instrument.

光学仪器的目镜上的细线、圆点、十字型细线或金属丝组成的系统。

youdao