入射光线

(a)  

法线 something regarded as a normative example

(a)  

汇聚 to move towards a place from different directions and meet

(a)  

视觉错觉something that tricks your eyes and makes you think that you can see sth that is not there, or makes you see sth as different from what it really is

(a)  

介质

something that is used for a particular purpose

(a)  

使折射

(a)  

焦点a thing or person that is the centre of interest or activity

(a)  

月相 a time when the moon presents a particular recurring appearance

(a)  

渐盈的(of the moon) pertaining to the period during which the visible surface of the moon increases

(a)