About: http://webisa.webdatacommons.org/178008563

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	A light source, such as a light emitting diode, is positioned at a fixed point on one side of the disk while a light sensor, such as a photosensitive diode, is positioned at the other side of the disk.
http://www.w3.org/ns/prov#wasQuotedFrom	google.ca