Lasers generate coherent light, ie light comprising photons with the same wavelength and in-phase.
This allows the light beam to be focused to a very small spot size similar to the actual wavelength of the light itself. The advent of lasers and in particular low cost laser emitting diodes has allowed the compact disc technology to become one of the most successful consumer electronic technologies of all time. In the late 60s, Philips developed the laser video disc, the first such application of the laser for a consumer electronics product. The 30cm disc was capable of storing up to 60mins of analogue video per side. A low power laser was used to read the video information stored in pits in the disc surface.