Natural materials all have a positive refractive index .
所有的自然物体都有阳性折射指数。
Refractive associations with age-related cataracts : the shihpai eye study .
屈光与年龄相关性白内障的关系:石牌眼疾流行病学研究。
Because shock waves represent a stark and sudden change in refractive index , they show up clearly in schlieren photographs .
因为冲击波反映了折射率的明显和突然的变化,他们能在纹影摄影中清楚地被展现出来。
In natural materials , light waves entering at an angle always bend to plunge more steeply into the material-the hallmark of a refractive index greater than 1 .