The photons shoot off through the lasing material in all directions, hitting other atoms and making them fire off photons too. Soon there are billions of identical photons zooming around within the tube. Mirrors at either end, however, reflect photons moving straight up and down the tube so that they zoom back and forth again and again, gathering more photons as they go. One of the mirrors is designed to let a fraction of the photons through and after a while they surge through. Immediately, the laser flashes out its intense beam.
Some lasers send out a continuous beam.
Powerful pulsed lasers shoot out a beam at regular intervals. How lasers are used Lasers are used in a huge number of ways, apart from spectacular light shows. Geologists, for instance, bounce them off satellites for a perfect measure of how the continents are moving. Doctors use them for delicate eye surgery and to cut bloodlessly into the body for surgery. Compact disc and video disc players rely on laser light to pick up the fine indentations on the disc that carry the recording.