一种光学装置，可将物体虚像投影到一平面之上，多用于跟踪。

An optical device that projects a virtual image of an object onto a plane surface, especially for tracing.

youdao

一种光学装置，可将物体虚像投影到一平面之上，多用于跟踪。

An optical device that projects a virtual image of an object onto a plane surface, especially for tracing.

youdao