"Star Wars," "Star Trek," "Battlestar Galactica" -- laser technology plays a pivotal role in science fiction movies and books. It's no doubt thanks to these sorts of stories that we now associate lasers with futuristic warfare and sleek spaceships.
¬But lasers play a pivotal role in our everyday lives, too. The fact is, they show up in an amazing range of products and technologies. You'll find them in everything from CD players to dental drills to high-speed metal cutting mac-hines to measuring systems. Tattoo removal, hair replacement, eye surgery -- they all use lasers.

But what is a laser?

What makes a laser beam different from the beam of a flashlight?

Specifically, what makes a laser light different from other kinds of light?

How are lasers classified?

Tell me in your own words without looking it up on wikipedia!

Also what do you think will be invented next with laser technology?

LASER = Light Amplification by Stimulated Emission of Radiation.

ahhhhhhhh

now we're in MY field

I have to leave early this mornin so I might not be able to do all this first thing in the mornin

imagine a atom. circling the atom is an electron. there are energy levels around the atom. specific levels, there are no in betweens. the electron is at this level or the next one up depending on the energy in the electron

added energy will cause the electron to momentarily jump to the next level up. But its not stable and will fall back down to its original level. as it does that excess energy is shed as a photon. one little spark of light

an example is when you heat metal and it glows. But that is not a laser

a laser forms when you add enough energy to get a "population inversion" where more electrons are at the higher leverls than are not

then they all fall back and emit a LOT of photons.

put a mirror in an EXACT straight line through the axis of the material to reflect those photons in on themselves. eventually after a long time (picoseconds) those reflected photons will bump other photons continuing the process and they will all be following that straight line of the mirrors.

now make one mirror 98% reflective. that two percent that escapes is your laser beam

Highly interesting. Thank you for contributing your knowledge in the area

a laser is physically coherent and temporally coherent. meaning that all the photons are in phase with each other

imagine light as a sine wave

white light is millions of sine waves all out of phase

a laser is millions of sine waves all in phase

and a laser has to be collimated or it spreads like any other light

a source of light before a lenses focal point will spread (diverging) and have a wavefront that looks like this )))))

a source of light after a lenses focal point will converge to a point (like a magnifying glass frying ants) and will have a wavefront like this (((((

at soucre of light exactly at the focal point will focus at infinity and that is collimated and its wave front looks like this IIIII

OP, I have one correction......There were no Lasers on Star Trek, they used Phasers and Photon Torpedoes.

there are diode lasers

gas lasers

crystal lasers

and vcsels (vertical cavity surface emitting)

diode lasers are cheap and low power and are used in CD players and bar code scanners

gas lasers, the most common are HeNe (HeliumNeon) the neon is the lasing material but the neon atoms are really small and hard to lase so Helium (large atoms)are excited and used to bump the neon atoms up to the energy levels

CO2 lasers use Helium to bump the CO2 atoms but they are hard to get them to fall back down and emit photons so Nitrogen is used to bump em down. and the gas mix has to be just right or it wont work. Those are used for welding

VCSELS are the best and most expensive lasers but at my last knowledge they were not real stable. they would "mode hop" with temperature changes so you would get different wavelengths depending on temperature

What do you think will be invented next with laser technology that may change much in the future for mankind?

hahaha if I knew I would be a billionaire

now if you focus and collimate gravity waves...


EDIT I have to run so I'll check back later

places to be and people to do...

I know of a lady who invented a laser lie detector and it is now used by the F.B.I. supposingly.

She is a millionare living in Miami Beach .

Of course I never seen the gadget and am not sure if she is telling the truth, yet if so, then I can imagine she made some money off this invention indeed.

the last company I worked for invented a system to diagnose vision defects.

shine a weak laser perfectly collimated so the wave front of the beam has absolutely no abberrations or bobbles into the eye. infra red so its invisible and wont make you blink. the laser reflects from the spehrical back of the eye and any imperfections in the lens of the eye is imparted into the beam

then the beam reflected out of the eyes can be computer analyzed and get an exact mathematical representation of the imperfections in the eye using zernike coefficients (those are way over my head) and get a prescription for eyeglasses

its in use heavily in Europe but the FDA hasnt approved it for America yet

they also use it for real time analysis while performing lasik

and lasers are dangerous

if you have a weak beam of say .1 watt per centimeter squared and shine it into an eye

the lens of the eye focuses that .1 watt to a pinpoint and that is enough to burn out the retina

no rings or watches allowed when working with lasers. the reflection can blind you

Yes I have known a person who had laser eye treatment here in Miami and he is now not able to see correctly anymore because of a slight mistake in the operation.

I think it is very dangerous indeed! Just imagine a eye doctor is trying to fix the eye with a laser and the patient suddenly slightly moves what that can do for the eye!

I just want my laser pointer to make that laser noise you always hear in the movies. I'd pay extra for that.

Seriously, though, thanks to Quiet for the posts..... laser technologies are fun reading, fascinating, and not conceptually difficult to understand at a high level. I'd love to understand it at lower levels, but I suspect that not only would it take a significant amount of explanation, it might be beyond me even at its simplest.

lasers are like sex. they operate by stimulated emission.

Oh now I understand

you pump the cavity until there is an incredible energy state inversion, then the slightest emission causes a tremendous avalanche effect resulting in the release of tremendous coherent blast!!

sighhhhhhhhhhhhhh

*lights cigarette*

was it good for you?