Audiovisual products such as slide projector, projector, leveling instrument etc.

主要生产幻灯机，投影仪等电教产品及水准仪等测绘仪器。

Imagine a slide projector showing a red and a blue image on the same screen.

想象一个幻灯放映机在屏幕上同时放映红色和蓝色的图像。