KnowraRuby laserLinked fromLinked fromThe 6 pages that link to Ruby laser, each with the reason it gives.All 6Broader topic 4Compared with 2Helium–neon laserCompared with: It is an early solid-state alternative, unlike the continuously operated gas-discharge helium–neon laser.Nd:YAG laserCompared with: Its three-level operation requires more pumping than Nd:YAG’s four-level transition.