Laser
The advantage of laser beams over light beams is that the laser beam widens (expands) only very little and has a high luminous density (concentration). In certain crystals, laser beams can be created with the help of energy (solid state laser, semi-conductor solid-state laser, laser diodes). This is also possible for certain gases (helium, neon, CO2 gas laser). Depending on the type of construction the laser beam can be visible (usually red) or invisible. Due to high radiance you should never look directly into a laser beam. Depending on their power, lasers come in different categories or classes. Measuring tools usually contain Class 2 lasers which do not require special safety measures.