Editing Laser lighting display (section)

=== Diffraction ===
A less complicated way of spreading the laser beam is by means of [[diffraction]]. A [[diffraction grating|grating]] splits the [[monochromatic]] light into several rays, and by using [[hologram]]s, essentially complicated gratings, the beam can be split into various patterns.<ref>{{cite web|url=http://www.galaxy3d.org/ |title=GALAXY 3D LASER LIGHT SHOW |publisher=Galaxy3d.org |access-date=2012-02-07}}</ref><ref>{{cite web|url=https://www.youtube.com/watch?v=h4I4uF5w9u8  |archive-url=https://ghostarchive.org/varchive/youtube/20211212/h4I4uF5w9u8| archive-date=2021-12-12 |url-status=live|title=Movie of consumer-grade diffraction based laser display |website=[[YouTube]]|access-date=2013-04-11}}{{cbignore}}</ref>

Diffraction uses something referred to as the [[Huygens–Fresnel principle|Huygens-Fresnel principle]]. The basic idea is that on every wavefront exists a forward propagating spherical wavelet of light.  The initial wavefront manifests itself in the form of a straight line, as if the subject was seeing a wave coming in towards themselves in the water.  Aspects of the spherical waves that divert sideways are cancelled with the sideways components of the wave points on each respect point on either side. Diffraction is the primary method that many simple laser projectors work.<ref>{{Cite web|url=https://www.boundless.com/physics/textbooks/boundless-physics-textbook/wave-optics-26/diffraction-175/huygens-principle-636-5593/|title=Boundless Physics|date=14 November 2016|website=Boundless Physics|access-date=14 November 2016}}</ref>  Light is projected out towards multiple points.