So what is the design type (Ivanoff corrector)?.
If so from my reading its probably limited to about 90 degree fov anyway (20mm on FF).
Or is it aspheric (if so I'd have expected it to be matched to a specific lens).
Or is it a compound optic (doublets)?
I'm interested to hear anything more (when was it designed and what was its original purpose.
FWIW Leica (Elcan) designed some interesting ports but all were prototype or very low volume (military) production, and being Leica are ludicrously price collectables today). One was even incorporated into a 35mm camera housing and marked as '90 degrees' rather than the focal length. The technology is probably quite old (I have some papers showing complex correctors for any lens up to about 90 degree FOV) but mass production of a viable system has never seemed to have been economically possible.