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 Sometimes it is hard to see the light, especially it lies in the invisible spectrum¹, like ultrared, ultraviolet radiation. But if you long to see the unseeable, you might interested to hear that under certain conditions people can catch a glimpse of usually invisible infrared² light. That's according to study of proceeding³ of national academy of science. Our eye sensitive to elementary particles called photons that have sufficient energy to excite light sensitive receptive protein in our redness. The photon in infrared radiation in the other hand has less ?. We can detect those lower energy photon using sometimes called light vision camera or J, but naked eye is usually blind to infrared radiation. But recently researchers at laser lab notice that they sometimes solve flash of light while working on the device made of brief infrared poses. So they feel the test to recognin cells erupted with their laser. When the light poses rapidly enough that the receptors can get hit with two photons at the same time, which supply enough to excite the receptor. That double dose make the infrared visible. One application of the finding is that it could give doctor new tail to diagnose of disease of retina. So you could id trouble before my otherwise be seen.