LASER – Light Amplification Stimulated Emission of Radiation (it’s always spelt with a ‘S’ not a ‘Z’!)
Characteristics of a laser:
- High intensity
- Diode laser typically outputs a 6mm beam
- Optical coherence – all of the photons are in lockstep
- Monochromacity – single colour. Visible spectrum range used in display lasers is 400nm (blue) – 700nm (red)
- Collimated / low divergence – known beam spread, measured in milli radians (mrad). Typical values are 1 – 1.3mrad (1mrad @ 100m = 10cm beam)
- Directional
Ion laser
Original types of lasers. Glass tube filled with inert gas. E.g. argon, crypton. Nobel gasses.
Better beam quality than modern diode lasers, 2mm wide beam, solid colour. Old timers often lament how much better their colours were.
Electrodes placed each side of type cause spark across gas, molecules emit photons, crash into each other and emit more photons. Mirror at each end causes them to travel along tube, one end lets ~10% out which is your beam.
Used lots of power and created lots of heat so needed water cooling.
The complexity of their power system and their large glass tubes meant they we’re temperamental and fragile!
Diode laser
Newer lasers are diode based, and the invention of these is what has facilitated the explosion of display lasers use.
Typically output a 6mm beam
Resiliant
Compact and simple
Low voltage
Air cooled
Long lasting and reliable (typically 5,000 – 20,000 hours)
More efficient, lower power. 30W laser probably pulls ~4A @ 230V
