Originally posted by DA Morgan:
The point of the mirroring, which often happens by total-internal-reflection (TIR) is that photons Stimulate the Emission of Radiation ... thus SER in laSER. If the photons do not make multiple passes there is less likelyhood that they will collide with an excited atom and stimulate further emission.
This is not significantly different than the reason why neutron reflection is used in nuclear weapons.
the only way you can have "tir" is if you use cavity dump pulse lasers. these have 2 high reflecting mirrors (hrm) but will open for a single pass of the light so that all of the energy in the cavity will dump out in a single pulse. in a normal laser one is a hrm and other a lrm (low reflective mirror). it only reflects a percentage of the energy, anywhere from 1 percent to 99 percent, perhaps even with a few points past the decimal. It all depends on what kind of medium and how big it is.
one of the ones that does not use mirrors at all is what is commonly called a jet laser. it uses a fuel that after combustion has high energy co2 and no2 as its exhaust. the exhaust is then fed into a chamber that causes it to travel a wide but low path, where a initiator beam is fired into it, to cause the stimulation. some forms of this will have the beam chamber a little higher and cause the beam to travel though it on parallel course two to four times. the trick is that no part of the exhaust has the beam travel though it more than once. this is suppose to create a extremely powerful beam. it was hoped at one point that it could be used as an antimissile or aircraft gun. while it worked on drones, it never was very effective on faster, bigger targets like aircraft, and even less on smaller, even faster targets like missiles.
one of the biggest laser in the world was called antares which was suppose to be used to create a hydrogen fusion to powered an electric power plant. scientifically it was a smashing success as it manage to cause fusion in more materials that hydrogen. it total took them off guard when it caused aluminum fusion.
financially, it was a huge bust. it did create more electricity than it used, enough to provide energy for a very small town. the cost to do so would have provided electricity for a medium size city using more conventional means. most dye lasers use a laser initiator too, using mirrors to change the path, rather than bounce it back and forth.
