While buying some darkroom equipment from a professional photographer a couple of years ago, I had asked if he had a light box he would part with. My wife was needing one and if I found one then I could borrow mine back. Anyway, what I ended up with is called a "Portable Transparency Printer" by Mfg Charles Beseler Co.
She said it was way to bright and gave it back to me. It is to much for looking at negatives. I am wondering if it is used in some process that I am not familiar with. Burning plates? It uses fluorescent bulbs with mirror like reflector.