Found it in the Lab #1

My lab space was used for storage for I don't know how long.  I've been steadily cleaning it out for a couple of years now - a little bit at a time.  Sometimes I find pieces of equipment from the long long ago, the before times, and I feel a little like an archaeologist.  Here's my current puzzle:

There is a tube on the backside with an eyepiece - if you look through the eyepiece you can see into the cylindrical chamber.  The hatch on the upright cylinder opens to a chamber of some sort, but it doesn't seem to be open to the top assembly.  Oh, and there's a light bulb on the side.  There appears to be a filament of some sort inside the top assembly, and its position can be tweaked by the variety of knobs seen in the photo.

Any clues?