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Luke Phillips
06-20-2007, 9:04 PM
Someone asked me what the temperature of the spot beam as it hits the surface of the material being engraved - I couldn't answer! :confused: Anyone have info on this? I've got a 60W ULS CO2 laser. Thanks

Mike Mackenzie
06-20-2007, 10:03 PM
Its hot enough not to put your hand under it. I don't know if it is heat or energy or both. Most laser tubes are pulsed what that means is a strong energy pulse that turns on and off in micro seconds that removes the material it is reacting to. Kinda like mini explosion's. temp of that I am not sure.

Kevin Huffman
06-21-2007, 12:22 PM
I am not sure if you can put a temperature setting with that, but if you could it would be determined by the material you are engraving.

With something like stone, where you are just breaking the bonds of individual grains to release them, I don't think it would get to terribly hot.
With something like wood, where it continues to burn after the laser has passed would probably posses more heat.

I have been working with lasers for about 6 years now and I do hear that question from time to time but I have never ever gotten an answer out of anyone. Not even the manufacturers.

Richard Rumancik
06-21-2007, 2:07 PM
Kevin is right, you can't really say how hot the beam is because it doesn't have a temperature - the temperature is a result of the heating effect of the beam energy on a material. When we cut, we set our speed so that the material melts/vaporizes/degrades at a suitable rate. There would be no point running slower than the approximate melting point or vaporization point. If we can only say that the material is getting up to 250C and then it melts, nobody will be really impressed.

If you stopped the laser motion and dwelled on a small particle of material suspended in space you could probably get metal up to a temperature that it melted. But in reality when cutting solids the particle will transfer heat to adjacent material so the maximum temperature will be limited by heat transfer rates.

If you want to impress someone, tell them that the 60 watt laser can focus the beam down to .003" (.08mm) which results in an intense power density of 12,000 watts per square millimeter.

Gary Hair
06-21-2007, 7:37 PM
Actually, there is a way to measure the heat output by a laser - every power meter uses the heat generated to determine the wattage. I don't know what temp the beam is, but it is most definately measurable. If you really want to know, I would check with a manufacturer of the meters and see if they will tell you exactly how they work. I did get this info from a power meter sales rep so I can't really say how accurate it is, but it made sense to me.

Gary

edit: just found this:
Wilmington, MA, July 2004…Ophir Optronics, Inc., leaders in advanced technology for the measurement of laser power, energy, beam profile and wavelength, introduces the new, Comet 1K Power Probe. The Comet 1K is a hand held laser power measurement probe designed to measure low to medium laser power. It is highly accurate, economical and is very easy to use.
The Ophir Comet 1K Power Probe can be used to measure laser power from 20W to 1KW. All that is needed to operate the Comet 1K is for the customer to set their laser to 10 second timed exposure, press the "ready" button, place the probe in the path of the laser beam and the Comet senses the temperature rise and measures automatically. The Comet 1K has a highly sophisticated algorithm to correct for the starting temperature of the puck so you obtain an accurate reading every time.
Additional specifications of the Comet 1K include: spectral range of 0.2- 20Ám; an absolute calibration accuracy of ▒5%; repeatability is ▒1% for same initial temperature; and linearity with power is ▒2% ▒1W from 20W to 1KW.
The Comet 1K comes with a swivel mount that rotates ▒90 degrees for ease-of- use, and a 2x8 character LCD. The Comet 1K will store the history of the last three readings and is CE approved.

The Company
For more than 25 years, Ophir Optronics, Inc. has set the standard for the measurement of laser power and energy. Ophir, an ISO 9002 company, employs over 200 engineers, technicians and skilled workers. The company manufactures optical instrumentation, optical components and non-contact optical equipment for distance measurement and three-dimensional mapping of objects. The company's products are sold worldwide in over 25 countries. Ophir maintains marketing, sales and service centers in the USA, Japan, Israel and Germany.

Bill Cunningham
06-21-2007, 11:25 PM
I just tell people "It's a beam of light, hotter than the surface of the sun" they say "cool" and walk away contented:D

Frank Corker
06-22-2007, 2:49 AM
Yep, I'm with Bill on that one, that's exactly what I say!

Ed Maloney
06-22-2007, 6:49 PM
"When you go into court, you are putting yourself into the hands of 12 people who weren't smart enough to get out of jury duty."

Good one Frank!