We have all heard of the double slit experiment. Here is my demonstration of it done with a simple green laser. Using black insulation tape I create a thin slit (about 1mm wide) in front of the beam. Then mount a piece of wire about in the middle of the slit. As the laser is a pointer I can adjust the beam so the wire is directly over the beam. Pointing the laser at a wall gives a diffraction pattern at right angles to the original slit, hence a double slit experiment!
Nice idea, but you won't get an interference pattern unless the slit is much smaller. I tried this a while back for one of my kids science class, and it was very difficult to make the slits narrow enough. I think I ended up using a razor blade...
Agree - I think this is merely scatter from a poor focus beam and not interference at all.
When we did it, we used a brass filament (the ultra thin invisible stuff - thinner than a hair) and a slot laser cut in a brass plate, and even then the results were not very good. And that was using a lab WATT rated laser (not milli-Watt) and professionally cut components. I think you need to go a LOT finer.
To make a crude but functional slit just blacken a microscope slide with soot from a candle and then draw a line on it with a razor blade. This will be a few microns wide and will give a good diffraction pattern.
