Comment Re:Actually optical choppers are very useful (Score 1) 137
Laser diodes, used in CD/DVD/whatever have a terrible beam quality for cutting and a mostly inappropriate wavelength, but they can be switched on/off quite fast. Think of fiber optics...
Other techs may be pretty slow to turn on/off, but have quite good beam quality for cutting. The most widely used is CO2 laser for that, which can take from 100's of us to a couple ms to turn on/off. With these lasers it's faster to move it optically away with mirrors of defocussing with lenses.