A reference beam is a laser beam used to read and write holograms. It is one of two laser beams used to create a hologram. In order to read a hologram out, some aspects of the reference beam (namely its angle of incidence, beam profile and wavelength) must be reproduced exactly as when it was used to write the hologram. As a result, usually reference beams are Gaussian beams or spherical wave beams (beams that radiate from a single point) which are fairly easy to reproduce.
The other beam used to write a hologram is the signal beam or object beam.
Famous quotes containing the words reference and/or beam:
“These roses under my window make no reference to former roses or to better ones; they are for what they are; they exist with God to-day. There is no time to them. There is simply the rose; it is perfect in every moment of its existence.”
—Ralph Waldo Emerson (1803–1882)
“Why beholdest thou the mote that is in thy brother’s eye, but considerest not the beam that is in thine own eye?”
—Bible: New Testament Jesus, in Matthew, 7:3.
From the Sermon on the Mount.