Laser Image Projector

Step 6 Spread the Dot

Using a concave lens, we expand the beam enough to cover all or most of the 35x24mm area of the slide. You can use 2 lens to expand the dot in a shorter distance, but brightness does suffer a little bit for each filter the laser has to pass through.

You can find these lens in old disposable cameras. The basic shape extrudes inwards and expands the beam.

If you want to buy some quality glass lens, then a number of reputable laser shops online can supply these.

As before set the lens within a 'holder' - using the polymorph or other materials. Set up another 'scaffold' and position the lens so that the beam of the laser passes directly through the centre.

Adjust the size of the expanded dot by moving the slide holder up and down until you're happy. This of course means moving the focusing lens too.

Once all modules are in alignment - you should see some sort of projection - if out of focus, then move the focusing lens back and forth relative to the slide to get the optimum sharpness.

A useful tool for alignment is lining up the main 'reflected' dot that will invariably occur to the centre of the preceding module element.

Comments

[jj.inc]

I wonder if you stick an LCD in front of this, moving green pictures!