He focused the sun's rays on a paper with a burning glass.

他用一面凸透镜把阳光聚焦纸上。

A physiotherapeutic apparatus for preventing and treating near sighted eye has a convex lens used as objective lens, lens cone, eyepiece, headgear and lens set.

一种防治近视的理疗器，它有镜的凸透镜、镜筒、目镜，还有头套和透镜，它用于人们近距离上长时间用时上，可以使被视的像清楚、放大和变远。