About: http://webisa.webdatacommons.org/399462197

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	If the region at which the focal point is formed is contaminated with a contaminant such as dust, light is cut off.
http://www.w3.org/ns/prov#wasQuotedFrom	google.com