Sherlock Holmes in black and white
Today I had an idea for an extension to the diffraction in a CD practical. How about comparing diffraction in a CD with diffraction in a DVD? So I fetched a DVD from the other room. Sherlock Holmes. We watched it the other day, not quite what I was expecting. I didn’t realise Sherlock was a Kung Fu master. So I held the DVD up like I do with the CD and couldn’t see any colours at all not even really close. On closer inspection it was possible to see something in the middle and at the very edge but nothing like the bright rings you get from a CD. This does make sense though; the pits on a DVD are much finer and closer together than a CD so the angle for interference maxima will be much greater. If it’s over 90° then you won’t see any colours at all.
According to how stuff works the distance between tracks is 740nm so we are on the right track so to speak.
