Laser cutting machine to build the condition of pulsed laser

Laser cutting machine of an atom from the high order to low-energy order, emit a photon, called spontaneous light. Atoms in the high order when hit by a photon will be stimulated and release another same photons, into two photons, called stimulated emission. If continue to produce the process of stimulated emission, is issued to the photon will be more and more. As long as we control the number of atoms of high-energy order in the number of atoms of higher than low order, stimulated the process of light will continue to produce, the control of light atoms stimulated device we call it 'optical amplifier. Laser is an application of the optical principles, but whether to how from ordinary light into the laser? It's need to understand the principle of atom glow. Can so many frequencies of light, at the same time gives us to build the condition of pulsed laser. Cavity has another function, that is to limit the frequency of the laser. Light to produce resonance in the cavity must be in conformity with the L = n lambda / 2 relationships ( L is the cavity length, lambda is wavelength, n is a fixed ratio) Not all frequencies of light, so can produce resonance in the resonant cavity, but only in accordance with the rules will resonate. However, the length of the resonant cavity ( L） Can a few meters long, and the wavelength of light, λ） Is in micron, between the two differ 1 million times, that is to say, eligible n range is quite large, rather than only a single frequency. Light emission out based on the speed of light in all directions, in order to make the light can be collected and tries to use continues to enlarge, it must be using the device, called 'resonant cavity' produced by optical amplifier of the light with a reflector is limited in a certain range, can make the light bounces back and forth, and the photons produced by light amplifier is the same, so the marching direction will be fairly consistent. Through the cavity effect, can make the light travel in the direction of exactly the same, that is to say, have the same resonant cavity with the direction of the light will be amplified, the rest of the different direction of the light will not enlarge, this is the first condition of generating laser.