公元1230年–1235年:罗伯特·格罗斯泰斯特描述光的应用:在他的著作De Iride提到, "...将小物体放在一个距离上会出现我们所期望的任何大小,在这个令人难以置信的距离上有可能阅读最小的字母..." ("Haec namque pars Perspectivae perfecte cognita ostendit nobis modum, quo res longissime distantes faciamus apparere propinquissime positas et quo res magnas propinquas faciamus apparere brevissimas et quo res longe positas parvas faciamus apparere quantum volumus magnas, ita ut possible sit nobis ex incredibili distantia litteras minimas legere, aut arenam, aut granum, aut gramina, aut quaevis minuta numerare.")[10]
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