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Jack Harper
03-25-2009, 9:44 AM
Does anyone have a recommendation for a model and supplier (other than Laser Bits) for a Laser Power Meter? Thanks.

Dan Hintz
03-25-2009, 10:01 AM
How much are you looking to spend? The digital meters (like what LaserBits rents) will start around $750, but you can get analog pot roast-cooking thermometer types for $100-$150.

George Brown
03-25-2009, 10:12 AM
How much are you looking to spend? The digital meters (like what LaserBits rents) will start around $750, but you can get analog pot roast-cooking thermometer types for $100-$150.
Do you know how accurate the analog ones are? And where would you get one. All I've seen are the expensive digital ones.

Rob Bosworth
03-25-2009, 10:41 AM
I would love to know where you can buy one for $ 100 to $ 150. I was looking for one yesterday, and the cheapest price I found was $300 for a Macken Instrument.

I have used digital, analog and the old " turkey thermometer analog meters. I prefer the "old turkey thermometer". Unless you drop them, they work the same every day. They do not care how the beam is profiled or the shape of the pulse, they just measure heat rise over a determined time frame.

Jack Harper
03-25-2009, 10:48 AM
I guess I was thinking of digital. I know Laserbits is a good company, but they are way in the middle of the supply chain and I believe are best suited to supply the small business to hobbiest and price accordingly. I prefer to buy straight from a manufactuer as I hold manufacturing and wholesale lisenses. Do you know what brand LB is selling?

Dan Hintz
03-25-2009, 11:10 AM
Jack, I believe it's the Power Wizard from Synrad... and last I checked, their price of $800 was what Synrad was selling it for. I've considered getting one myself, but $800 was a bit much to bite off for the occasional check (but I like the repeatability and readability of digital compared to analog). the PW is good up to 250W.

EDIT: Hmmmm, do I see another group buy coming on? :D

http://www.synrad.com/Products/powerwizard.htm

Rob, I'll see if I can dig up some of my links to the less expensive ones.

EDIT: Macken sells their probes directly for $260, but I know I have cheaper solutions bookmarked, I just have to dig them up.

Mike Mackenzie
03-25-2009, 12:06 PM
Rob & Others,

You can get the less expensive meters from here. www.macken.com (http://www.macken.com)

Robert Ray
03-25-2009, 4:02 PM
I have one of the Synrad Power Wizards (in calibration when tested) and I compared it's results on my 3 lasers with a Macken Puck type I borrowed from work, and found the results very close. <5% difference. Mine is a 0-250W digital, and the Macken was a 0-1000W puck type, which was hard to read.

What I did was take 3 measurements on each laser, with both the Synrad, and the Macken.

With the Macken, I laid the puck on a block of steel to cool it down to room temperature, and turned the dial to read 0W, then heated 20 seconds, and checked the power reading. Laid it on the steel block for several minutes before each test and re-zeroed as needed.

With the Synrad, I did the tests about 5 minutes apart, but did not cool it's small sensor area any. It's supposed to be self calibrating for relative temp anyways.

So the good news is, the puck type meter is good enough to save a couple hundred dollars over the digital, and both work well.

-Robert Ray

Dave Johnson29
03-25-2009, 6:12 PM
So the good news is, the puck type meter is good enough to save a couple hundred dollars over the digital


Robert,

Are you measuring in the raw beam or at the focus point with the puck type?

Dan Hintz
03-25-2009, 7:44 PM
Robert,

Are you measuring in the raw beam or at the focus point with the puck type?
Always the raw beam, never the focus point... just make sure the raw beam is completely within the boundaries of the tester block.

Jack Harper
03-25-2009, 8:33 PM
Thanks everyone I will do some research and make a decision soon. I have this feeling my laser is performing way under what it should. Since I have a Synrad Firestar sealed laser, it should have huge hours to go before needing a charge, but we will see.

Peter Meacham
03-25-2009, 8:48 PM
Jack

I was able to borrow a power meter from the US Service Center of my laser manufacturer (Trotec) - I just paid the shipping charges from/to them. Maybe your manufacturer would do the same.

Pete

Robert Ray
03-26-2009, 9:01 AM
Robert,

Are you measuring in the raw beam or at the focus point with the puck type?


I measured after the second mirror, always a fixed mirror. I also measured under the lens area (with lens removed) to see how much power drop there was, but remember to remove the lens, as you don't want the beam focused.

Robert Ray
03-26-2009, 9:03 AM
I am sure I read somewhere that someone rents their meter out? Maybe Sign Warehouse?

Dave Johnson29
03-26-2009, 10:00 AM
I measured after the second mirror, always a fixed mirror.


Thanks Ray,

I only asked as several years back I had made some puck meters and they are only to be used in the raw beam.

It is used purely as a comparator and does not measure actual Watts as they are really meat thermometers. I called them Power Meaters. :)

When the laser is new, you place it in the beam and measure the temp rise over a fixed period of time. They are surprisingly accurate if you can live with just a temp reading.

You then can use it to check any drop in performance over time. It is possible to roughly calibrate it for your set up if you can borrow a real one with Watts marked on it. OK, so not perfect but for the price they make do fine.

Mike DeRegnaucourt
03-26-2009, 7:19 PM
I found this site...maybe it can help. :)

Sam's Super Cheap and Dirty Laser Power Meter (http://www.repairfaq.org/sam/laserioi.htm#ioilpm3)

Richard Rumancik
03-26-2009, 7:39 PM
I found this site...maybe it can help. Sam's Super Cheap and Dirty Laser Power Meter

Hmmm . . .I don't think this design would work for a CO2 laser cutting system. I think it was intended for milliwatt type lasers. To determine the power from a CO2 laser you need to inject some serious energy into a mass over a period of time and determine the temperature rise. I don't think it would be possible to use a photodiode.

Dan Hintz
03-26-2009, 8:07 PM
I also do not have any idea at what point the photodiode array will be damaged due to thermal effects. This is certainly not a problem for beam power up to 10 mW as long as it is not focused to a sharp point.
:eek: I think you'd end up with a slag box for a photodetector after a test...

John W. Love
03-26-2009, 8:29 PM
I read it, and it bothered me that I understood it, But I agree that a 40W CO2 laser would turn it into somthing that would later have to be scraped off of the vector table.

Jack Harper
04-01-2009, 2:26 PM
I just wanted to say thanks for ever ones input on the power meter. I just picked up a Synrad Power Wizard for about half price off ebay. I had to to go toe to toe with someone, hope it was not a creeker, if so, sorry about that. Well at least in a few days I will see if my suspitions are correct on a loss of power.