Human eye has the capability to perceive the electro magnetic radiation which has wavelengths ranging from 400nm to 700nm. The Infrared Radiation(IR) has wavelength greater than 700nm. This means that a normal human cannot see IR.
But I'll tell you how is it possible to see the Infrared Rays.
- Take any remote which uses IR to transmit data. Usually all the television remotes are based on IR.
- Take a mobile phone equipped with a camera.
- Launch the Camera app in the mobile phone and point the IR transmitter(usually on top of the remote) towards the camera.
- Press any button on the remote.
Whoa! You just saw Infrared Radiation without any scientific equipment!