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:
“I am more and more convinced that, with reference to any public question, it is more important to know what the country thinks of it than what the city thinks. The city does not think much.”
—Henry David Thoreau (1817–1862)
“What do we plant when we plant the tree?
We plant the ship that will cross the sea,
We plant the mast to carry the sails,
We plant the planks to withstand the gales—
The keel, the keelson, and beam and knee—
We plant the ship when we plant the tree.”
—Henry Abbey (1842–1911)