Build a 20$ X Y laser scanner !

Here is a more powerful version which allows bigger deviation angle: display bigger pictures at short distances


After trying a lot of solutions to realize a very low cost X Y scanner for a laser pointer, I choose the "loudspeaker" way : Build a 5$ X Y Laser scanner !

Mechanical construction :

We still use 2 loudspeakers, bigger one for more angle deviation. The trick is to remove the central paper spherical dome which protect loudspeaker magnet part from dust. This allows to glue a piece like a screw to act as a fixed point for one mirror end. The other mirror end is attached to the mobile coil.

Then 2 loudspeakers are disposed in front together:

We use an improved 6bits DAC still connected on // port with a Laser On/off output:

And the same power amplifier ouptut:

All that installed on 2 little PCB connected through a RJ phone connector:

 

With a proper software: LASER.EXE write in old MS-DOS TURBOC for PC you are able to display characters like "26"

If you connect the scope on loudspeakers outptut in X(t), Y(t), display result interpretation isn't obvious:

A good trick : set the oscilloscope to "XY mode" : you must see exactly your display on the scope! in case of problem, connect the scope directly on the DAC output. (perhaps you need a capacitor to smooth). With a scope, you can understand that DAC and amplifiers must also be well made to get a good result : not only loudspeakers scanner !

Number "26" displayed on the scope (connected to loudspeakers output)

Number "26" displayed on a screen with a red laser with a 18 frame/s rate: (by night)

There are some distorsion (but LASER.EXE itself doesnt build perfect characters). Laser On/Off works well. Main problem is perhaps the oscillation due to parasitic vibration on vertical lines...(notice: the double line is due to a default in the laser diode itself which has got some injuries long time ago...)

It's only 18 frame/s which is the limit for blinking: that means that today, 2 characters are the maximum. We must still increase speed system to reach 3 or 4 characters on the same display.


http://spt06.chez-alice.fr/00/lasers.htm

E-mail :

03/06/05.