A signal beam or object beam is one of at least two laser beams used to write holograms. The signal beam is the beam that carries the information to be stored in the hologram. In the case of a holographic picture, this beam is reflected off the object being recorded, into the media. In the case of holographic data storage, the beam has some kind information encoded into it (for instance, it can be sent through a transparency or a spatial light modulator).
The other beam necessary to write a hologram is the reference beam.
Famous quotes containing the words signal and/or beam:
“A signal is comprehended if it serves to make us notice the object or situation it bespeaks. A symbol is understood when we conceive the idea it presents.”
—Susanne K. Langer (1895–1995)
“It was at that moment, just after Krug had fallen through the bottom of a confused dream and sat up on the straw with a gasp—and just before his reality, his remembered hideous misfortune could pounce upon him—it was then that I felt a pang of pity for Adam and slid towards him along an inclined beam of pale light—causing instantaneous madness, but at least saving him from the senseless agony of his logical fate.”
—Vladimir Nabokov (1899–1977)