: Typically AAA or lithium-ion batteries that provide the electrical energy.
: The most common and least expensive. They use simple diodes and are widely used in low-power pointers and barcode scanners. lazer pen
: A tiny semiconductor that converts electricity into light. : Typically AAA or lithium-ion batteries that provide
: 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