https://rusneb.ru/catalog/000224_000128_0000488231_19751015_...
-- click on "Skachat' PDF" (second from the top on the left). Unfortunately it is in Russian, not sure whether English translation exists.
This patent seems only for (X,Y) coordinate capture, but the same authors later worked on 3D setups as well.
EDIT: let me know if you need help with translation