Quote Originally Posted by Feign View Post
Attenuating a beam into a fine point is a serious pain. When I worked on beam attenuators I figured out a little trick for making them pretty cheaply that maybe could apply here.

The best method of attenuating a beam so that there is no scatter is to have a series of apertures spaced along the beam and perfectly lined up. In most cases this is a crazy machined assembly that's nearly impossible even at the 10mm beam diameter scale. But if you want a similar effect to the big expensive attenuators, just use a threaded hole with the thread ID the size of the beam you want (provided the material you use isn't at all reflective. I'd recommend a black anodized nut with the tiniest thread you can find.
what about using a series of varying aperatures, with the largest nearest the diode? wouldn't this work similarly but reduce the problem of alignment?