I came across links to Canon's "EF Lens Work III" yesterday. This is a series of 11 PDFs about Canon EF lenses which are free for download here. Some of them are little more than advertising brochures, but there is quite a lot of technical detail about how various lens technologies work (especially in "EF LENS TECHNOLOGY") and also explanations of various optical terminology and theory as it relates to lenses ("OPTICAL TERMINOLOGY & MTF CHARACTERISTICS"). These two are well worth a read with lots of fascinating details about the use of different sorts of glass, felspar lenses, etc in the control of aberration and about USM and IS technologies.
CANON'S CHALLENGES contains a brief account of the founding of the firm that eventually became Canon to produce the first Japanese 35mm camera in 1933. This was named the "Kwanon" after the Buddhist Goddess of Mercy.
