Not sure of the term, never thought to type "prism" in the search.
I have a back problem that makes it difficult to bend over effectively (getting a lot of Physio atm). I basically have to do the splits when viewing low (reminds me of my martial arts days).
I was just looking at a way of viewing with bending my too much. I know I expect to recover, but not sure when as I have neglected my pain problems for many years until now.
I remember seeing a device in the movie "Knowning" but wasn't sure whether it was just a prop.
"edit" - I was hoping to use off the shelf products to make it. I am not worried about image inversion.