: The most common and least expensive. They use simple diodes and are widely used in low-power pointers and barcode scanners.
: Appears much brighter to the human eye because our vision is most sensitive to the green spectrum. These are popular for stargazing as the beam is often visible in the air. lazer pen
: A tiny semiconductor that converts electricity into light. : The most common and least expensive
: A lens at the tip focuses the scattered light into a tight, parallel beam that stays concentrated over long distances. A Spectrum of Colors making them glow. Safety and Classification
: Often more powerful and can cause fluorescence in certain materials, making them glow. Safety and Classification