About: http://webisa.webdatacommons.org/421203546

Property	Value
http://www.w3.org/1999/02/22-rdf-syntax-ns#type	http://www.w3.org/ns/prov#Entity
http://www.w3.org/ns/prov#value	In other embodiments, it may be spaced so that there is a variation in the optical index of refraction between the plane where the image is formed and the film.
http://www.w3.org/ns/prov#wasQuotedFrom	google.com