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眼镜是老年人的朋友,它不仅能改善视力,保护眼睛,还会使人美观。但是,必须选择得当,否则,会伤害眼睛。首先要知道从功能上分类,眼镜有矫治镜和防护镜两大类,也有两种作用兼而有之的。 防护镜:这是一种没有屈光度的防护眼镜,像风镜、太阳镜、厂矿工人防尘镜,以及电焊、炼钢工人用的蓝玻璃滤光镜等,都是平光镜。通过这种镜片观察物像,大小、形状不变。镜片的物理性能要求有
Glasses are friends of the elderly, it can not only improve eyesight, protect the eyes, but also make people beautiful. However, you must choose the right one, otherwise it will hurt your eyes. First of all, to know from the functional classification, glasses and protective glasses are two categories, there are two effects of both. Goggles: This is a non-diopter protective glasses, goggles, sunglasses, miner’s dust-proof mirror, and welding, steel-making workers with blue glass filters, etc., are flat mirror. Observe the object through this lens, size, shape unchanged. Physical requirements of the lens