zero diopter

例句：

1. 1.The zero diopter is used to measure the distance between two points on a surface.
   零屈光度用于测量两个表面点之间的距离。
2. 2.The zero diopter was used in ancient times to measure the size of objects.
   零屈光度在古代被用来测量物体的大小。
3. 3. The zero diopter is essential for accurate measurements in photography.
   零屈光度对于摄影中的准确测量至关重要。