permanent-magnetic lens

例句：

1. 1.The camera uses a permanent magnetic lens to focus the image.
   相机使用一个永久磁性透镜来聚焦图像。
2. 2. The scientist used a permanent magnetic lens to observe the phenomenon.
   科学家使用一个永久磁性透镜来观察这个现象。
3. 3.The lens was made of glass, which is a type of material that is both permanent and magnetic.
   透镜是由玻璃制成的，这是一种既永久又具有磁性的材料。