Earlier this year, I bought one of those K40-style laser machines that was listed at a ridiculously low price, and it arrived broken. Well, let me qualify that: the laser tube and the power supply ...

A lot of the DIY laser engravers and cutters we cover here on Hackaday are made with laser diodes salvaged from Blu-ray drives and projectors, which are visible lasers in the 400 – 450nm range ...