Have you seen Infrared rays so far? It is difficult to see because it is beyond the spectral response of our eye. Our photosensitive cells in the retina detect only the visible light in the range 450-750 nm. But many animals can see infrared spectrum lying above 900nm.Then what we can do to check whether, the Infrared LED in our project is working or not. A Digital camera can solve the problem. See how it detects the infrared.
See more in this link http://www.engineersgarage.com/contribution/how-see-infrared-rays