# Lasers are being used to do eye correction

Lasers are being used to do many things now: eye correction, speed scaning, cutting, and now even to create iron!

Scientists now use lasers to heat up hydrogen so they fuse into helium and all the way up the table into iron, just like stars.

I want to know if lasers have mass. I know that they are just photons in a narrow beam, and photons have mass (or do they?), so lasers must have mass too, right?

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Yes they are just a monochromatic (same color) beam of photons. Photons do have mass, but no rest mass. So lasers beams do have mass.

Most lasers are very large pieces of heavy equipment that require water cooling and many amperes of power. So yes, I would say they have lots of mass....

Ralph

RalphS said:
Most lasers are very large pieces of heavy equipment that require water cooling and many amperes of power. So yes, I would say they have lots of mass....

Ralph
:uhh: He's talking about the beam, Ralph...

I disagree with Ralph. Most lasers are compact pieces of lightweight equipment that don't require any special cooling and are found in everyday electronics. So they have SOME mass...but not that much.

HallsofIvy
Homework Helper
When I was in college, they showed us a laser, in its own dedicated lab, filled with equipment for cooling and adjusting it. Yesterday, I saw a laser on sale at "Home Depot" hardware (to be used for establishing a straight line- remember chalk lines?). It was about 10 ounces and they were asking $25. russ_watters Mentor HallsofIvy said: When I was in college, they showed us a laser, in its own dedicated lab, filled with equipment for cooling and adjusting it. Yesterday, I saw a laser on sale at "Home Depot" hardware (to be used for establishing a straight line- remember chalk lines?). It was about 10 ounces and they were asking$25.
So, you're saying....you're old?

Integral
Staff Emeritus
Gold Member
As far as the LASER itself goes (The beam is NOT the LASER!) they come in all sizes and shapes. From the small LASER diode pointer to High power industrial LASERS which can be very massive. I'll bet that the LASERS used to fuse Hydrogen are HUGE! They may well fill rooms with cooling equipment.

Our 10W Coherent AVIA X Lasers have a head (the actual LASER ) that weighs about 30Lbs it sets on a water cooled chiller plate. The Chiller (water cooler) which pumps water to the chiller plate is a box the size of a large suitcase. The LASER power supply, which also contains the control electronics and the infra red solid state LASER diodes for pumping the LASER, is yet another suitcase sized box which weighs about 90lbs. This is a 10W industrial laser, as the power goes up the size must also increase, just the nature of the beast.

http://www.cohr.com/Products/index....s.Part&PCID=23&PLID=34&PDID=300&PTID=DPSS0002

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HallsofIvy
Homework Helper
russ_watters said:
So, you're saying....you're old?

I prefer "antique"!

neutroncount
How bout "ripe with experience"?

Njorl
At the other extreme, some guys I work with made a VCSEL (vertical cavity surface emitting laser) that was <10 micron diameter, and about 3 microns deep.

This devolved into unintended territory pretty quickly.

I think this would be illustrative of the question first asked:

Consider two laser beams of extremely high power and good collimation. Would there be a gravitational attraction between the two beams? Considering our current state of the arts of laser making and detection, could we detect that gravitational attraction?

Njorl

It seems a rather exspensive way to make iron, when we live on a planet mostly made of it.

Also, in natural fusion, iron is the rest spot for things going up or down the P table, things going up the table, Hydrogen to Helium and so on, run out of returns at iron, so it stops there. things going down, once it gets to iron, it starts to sustain its self AS iron. but using lasers, as an exsternal power for the fusion, could it not continue to make things more dencer than iron?

and yes i am awear that i made almost no sence.