That would be me...
You inquired about the OPAQUE PROJECTOR.
There was one in my room when I started to teach art 25 years ago, the
art room was the place to put big bulky items, I discovered it was very
useful to show books and illustrations, you could also show 3D objects.
One day the bulb burned out.....it was a dinosaur, and took the
secretary on a research inquiry.
On occasion I used the bulb alone (seemed like 1000watts) to project
JK from Long Beach CA