Final year project (Electronics engineering) - LASER PROJECTOR
The basic idea of the Laser Projector is to create a character projector that can be interfaced to a mobile device, or linked to a PC via a serial port. By switching on and off a laser beam being reflected off a rotating polygonal mirror, it is possible to display dot matrix style text onto any surface. The prototype we have built uses laser diodes salvaged from cheap key chain laser pointers along with a rotating polygonal mirror which is driven by a brushless dc fan motor. A microcontroller controls the motor speed and the lasers.
The system is closed loop: an IR LED/photodiode combination signals the microcontroller chip when the mirror is at its origin, which enables a precise overlapping of the laser pulse sequences. The microcontroller used is the Atmel 89s52 which has 8K bytes of reprogrammable flash memory, which allows storing character templates for the complete alphabet as well as the entire ASCII character set. Arbitrary text can be sent to the projector via the serial port and displayed; in addition to that, preset text stored on the projector itself can be displayed.
The current prototype has a built in user interface which uses the serial port and windows(xp) hyper terminal to accept characters to be displayed from the user and change parameters like character size( horizontal dash length), scroll speed and number of characters displayed at a time.
Although the display leaves much to be desired by way of brightness and projection distance, it proves that displays using rotating polygonal mirrors and inexpensive laser pointers are quite possible to build..
THis project was carried out by Shakir( thats me :)) Aditya, Vrandesh and Shrikant as part of our final year curriculum.
WAtch a short video of the device in action here:
MAny thanks are due to Stefan Marti, MIT Media Lab, whose work and fabulous documentation on the TIny projector provided us with very valuable insights and helped us to a great extent in our own work.
COUNTRIES since 25 September 2010