What is a laser

[pakigang]

Have been thinking what is laser, a concentrated light or energy or some type of waves. How laser differs like some are used in operation and some used to cut objects and even for eye operations?

 

[xSauronx]

Behold the wikipedia

may be a good intro; haven't read it myself

 

[esun]

It's all three. Light, energy, and waves are all encompassed by lasers. Lasers are a form of electromagnetic waves, which if you check a physics textbook, you'll see are basically perpendicular electric and magnetic fields varying with space and time. Of course, electric and magnetic fields store energy. The important difference between lasers and typical light bulbs is encompassed in this statement from that Wikipedia entry: "a laser generally emits photons in a narrow, well-defined, polarised, coherent beam of near-monochromatic light, consisting of a single wavelength".

 

[RichPLS]

Lasers are also valueable tools for terrosts to use to bring down airliners when landing.
Also good for getting investigated by the FBI for suspicion of being terrorists responsable for attempting to bring down airliners while attempting to land...

 

[Jeffyboy]

Apparently laser pointers are fun to point at FBI helicopters too..hehe. If you want to be detained and questioned and probably probed in some ghastly manner.

Jeff

 

[Jeffyboy]

Lasers come in gas, ruby, and other types and give off different wavelengths of light. Some are pulse, or continuous. Really depends what you want to do but the basics are the first laser used a ruby tube to amplify the light pumped in to it

 

[Pohemi]

Light
Amplified by
Stimulated
Emission of
Radiation

In a laser using a rod (ruby, emerald, diamond, etc...), a flash tube surrounding the rod is used to charge the rod with energy. Typically both ends of the rod are mirrored; one completely and one partially. Once the rod is charged by the flash tube, the atoms in the rod become excited. The only way for these atoms to return to their normal state is by releasing energy in the form of photons. This energy is directed out the partially mirrored end of the rod, already focused in nature (it does not diffuse like normal light).

 

[Mday]

light is energy.
laser is light.

the difference between light you come across every day and laser is that there is only one wavelength (coherent) in a beam of laser versus a beam of light which would have several. what does this mean? if you shine a flash light, the beam is pretty much going to expand like a cone. with a laser, this will still happen, but the cone is very sharp so you can consider a laser a point light source. you will not see a laser beam from the side without any reflections. since the laser is point light source, if you shine a laser and a flash light witht he same output, the laser will output more energy to a concentrated area. this is without any fancy optics. since the laser is coherent, the laser is also capable of using that light energy more efficiently getting light from one point to another. that is why lasers are used in fiber optics and not a big ass light bulb. laser LEDs are also more energy efficient, so they are fairly popular in modern electronics.

read this:
http://science.howstuffworks.com/laser.htm

 

[KalTorak]

Originally posted by: RichPLS
Lasers are also valueable tools for terrosts to use to bring down airliners when landing.
Also good for getting investigated by the FBI for suspicion of being terrorists responsable for attempting to bring down airliners while attempting to land...

And what's the worry there, really? I mean, wouldn't a cheap polarized film on cockpit windows clear that right up?

 

[Gibsons]

I mean, wouldn't a cheap polarized film on cockpit windows clear that right up?

Nope, laser light isn't necessarily polarized, and even if it is, the bad guy can rotate his laser 90 degrees.