virtual keyboard is made of infrared laser light. As a result the 
keyboard can be projected onto any flat surface. A separate infrared 
sensor tracks the keys as they are tapped. A virtual keyboard is created
 using both visible and invisible light. The visible light is used to 
project the keyboard on to a surface, and invisible infrared light is 
used to track the keystrokes.
How a virtual keyboard works:
1. A Laser projects a visible virtual keyboard onto a level surface.
2. Invisible infrared beam is projected above virtual keyboard.
 
3. The finger makes keystroke of the virtual keyboard. This breaks the 
infrared beam and infrared light is reflected back to the projector.
 
4. Reflected infrared beam passes through an infrared filter for the camera.
 
5. The camera photographs angle of incoming infrared light.
 
6. The sensor chip determines where the infrared beam was broken and 
translates it into co-ordinates and characters are created on screen.
  
A virtual keyboard is a small projector transmits an image of a keyboard
 layout on any level surface, like tables etc. A sensor inside the 
projector captures keystrokes, converting them into on-screen 
characters. To create the illusion of a real keyboard, the projector 
makes a clicking sound when a keystroke is made.