You can see the queen is made of little plastic dots on clear plastic The region that I got the best diffraction from was under the Queen’s chin and you can see the ordered spacing that created it here
Hi Alessio, I shone the laser through clear maple leaf is. The blue dot in the dollar below.
The dollar I had is in the IOP Electromagnetic Workshop box and was a shown at the East Midlands day. I seem to remember that I could see no dollar pattern and was convinced that it is a true diffraction pattern. When I get hold of one again I will use my dino-light microscope to have a look. In the pictures above I used the dino-light to magnify the £5 pound note enough to see the little blobs of plastic.
An interesting feature of the old 5 pound note was the infrared security feature.
Using a cheap webcam with the IR filter removed. If you shine an IR LED and block the visible light entering the camera. Then on the note you only see half the Queen’s face. I have been told it works on the new £20 but have not tried it yet.