A controller drives the objectivelens via a focusing unit, and detects peaks in the reflected light signal obtained when the objectivelens is driven in a focusing direction.
控制器经聚焦单元驱动物镜，并且检测在当在聚焦方向上驱动物镜时得到的反射光信号中的波峰。
2
Although, Photographic optical lens can be used as objective projected. But Projection objective has some different.