List of members with power meters

To knimrod.
Look. I have been having a go at your power "meter" but calling what I say "BS" is taking it too far.
Listen. I know perfectly smegging well the head is calibrated. But the amplifier is NOT genuine Coherent, is NOT made with instrument grade components and is NOT, BOTTOM LINE, as accurate as the original one, modified or otherwise.

However the spirit of a kenometer or any non-logging or non- professional meter is the same. I maintain that your design is not as accurate as Kenom's but to 99% of users the result is the same.

I was harsh to exclude DIY'ed ones so I'll shove you in.

People who want more than a "yeah, i think it's about... yeah its about 185mw, yeah about that" can always come to the people with professionally made meters for a more accurate result. (I may be exaggerating just a little... )

BlueFusion said:

To knimrod.
Look. I have been having a go at your power "meter" but calling what I say "BS" is taking it too far.
Listen. I know perfectly smegging well the head is calibrated. But the amplifier is NOT genuine Coherent, is NOT made with instrument grade components and is NOT, BOTTOM LINE, as accurate as the original one, modified or otherwise.

However the spirit of a kenometer or any non-logging or non- professional meter is the same. I maintain that your design is not as accurate as Kenom's but to 99% of users the result is the same.

I was harsh to exclude DIY'ed ones so I'll shove you in.

People who want more than a "yeah, i think it's about... yeah its about 185mw, yeah about that" can always come to the people with professionally made meters for a more accurate result. (I may be exaggerating just a little... )

Click to expand...

I still don't see how a mere amp can throw off the readings by a LOT, especially if the gain is set right. ok, maybe 1mW off compared to the kenometer. unless you want someone to measure the power of your 2mW DX red, you will fine with anyone, DIY or not.

regards,

amk

BlueFusion said:

Just had a neat idea. I have a laser power meter capable of logging data, so as such I am more than happy to accept lasers mailed to me to measure and return, provided return postage costs. But it's not just me.

Many people here have meters, a lot more now that Kenom's deals are about. So I thought I'd write up a quick list of who has a power meter.

Now there's several parts here. If you want a full report, graphs etc on your laser there are a few people with meters capable of this. If you just want a basic power estimate / measurement without graphs or anything fancy, people with Lasercheck pens and Kenometers can probably help out there.

So: people with logging meters, people with basic meters, are they happy to accept lasers.
Here it is.

-- Tests? means do they accept lasers to be tested for free provided postage.

Person	Logging / basic	Tests?	Location
BlueFusion	Logging	Yes	Adelaide, Australia
pseudonomen137	Logging	?	?
Drlava	Logging	Yes	Cleveland, Ohio, USA
Kenom	Logging	Yes	Billings, MT
Hemlock Mike	?	?	?
yobresal	Basic	Yes	San Francisco, Ca, USA
xarylx	Basic	Yes	NY state, USA
You?	?	?	?

If you have any sort of power meter, just post here with what sort and whether you're happy to measure lasers provided return postage cost. I'll do my best to keep track.


BTW: I figure this is kinda a deal... People want their lasers to be measured and some can provide the service... so its sort of a deal. Didn't fit any better in any other board though.

Click to expand...

Count me in i have a coherent power check and i am located in the netherlands

Amk, if only it were that simple. A microscopic error in gain setting amplifies itself, as in the larger the measurement is the less accurate it is. This may not matter though.

I will get around to adding all these some day...

BlueFusion said:

To knimrod.
Look. I have been having a go at your power "meter" but calling what I say "BS" is taking it too far.
Listen. I know perfectly smegging well the head is calibrated. But the amplifier is NOT genuine Coherent, is NOT made with instrument grade components and is NOT, BOTTOM LINE, as accurate as the original one, modified or otherwise.

However the spirit of a kenometer or any non-logging or non- professional meter is the same. I maintain that your design is not as accurate as Kenom's but to 99% of users the result is the same.

I was harsh to exclude DIY'ed ones so I'll shove you in.

People who want more than a "yeah, i think it's about... yeah its about 185mw, yeah about that" can always come to the people with professionally made meters for a more accurate result. (I may be exaggerating just a little...  )

Click to expand...

You look... It's BS and I call 'em like I see 'em.  Every time you've interjected your 2 cents into the discussion about the DIY power meter project, you've been wrong.  Not only wrong but it's been mean-spirited.  

Here's the real "BOTTOM LINE":  You have absolutely no independent idea how accurate the DIY meter is, or the original for that matter, modified or otherwise.  Why you insist on pretending you do is beyond me.    However, if I'm wrong, I would gladly proffer an apology. Maybe you could tell us about your engineering background? How about you just tell us what an "instrument grade component" is and how it affects the circuit?  

BlueFusion said:

Amk, if only it were that simple. A microscopic error in gain setting amplifies itself, as in the larger the measurement is the less accurate it is. This may not matter though.  

I will get around to adding all these some day...

Click to expand...

Wrong again...  The error does not "amplify itself".  If there is a 5% error in the gain setting, say 1050 instead of 1000, the power would be off by 5% at 10mW (10.5mW) and still 5% at 1000mW (1050mW).  The error is a constant +5% over its range and therefore the accuracy remains constant.

   Sensor V       Amp    Amp Output
   (1uV=1mW)      Gain    (1V=1W)      
 (10 x 10[sup]-6[/sup])V   x 1000 = .0100V
 (10 x 10[sup]-6[/sup])V   x 1050 = .0105V

 (1000 x 10[sup]-6[/sup])V x 1000 = 1.000V
 (1000 x 10[sup]-6[/sup])V x 1050 = 1.050V

I've had occasion to examine 4 different surplus sensor heads so far.  Three were within 5% of each other.  One was off by 9%.  Of the 5 amplifier circuits I've built and calibrated, the gain was within 2%.  So, in my experience, the DIY amp is more precise than the sensor head.

Even the Coherent LaserCheck and LaserMate has a specified accuracy of +/- 5% (10%).  I'd say we're right in the hunt..

Curious here.  Exactly what amp board did kenom use?  I searched and could not find information on it.  Anyone have any pics of the guts of it?

BTW, the biggest source of error may be the DPMs.  Mine was not very accurate until I calibrated it.

chimo said:

Curious here.  Exactly what amp board did kenom use?  I searched and could not find information on it.  Anyone have any pics of the guts of it?

BTW, the biggest source of error may be the DPMs.  Mine was not very accurate until I calibrated it.

Click to expand...

I believe Kenom sawed the amp circuit portion from the PCB the sensor was originally attached to.  Lava posted instructions on how to modify the original circuit to yield 1mV per mW input here.  I think that's the basis for Kenom's meter and it should work nominally.

My 2 DPMs from China are pretty much right on the money.  My DPM from Jewell was off a bit.. Go figure..

chimo said:

Curious here.  Exactly what amp board did kenom use?  I searched and could not find information on it.  Anyone have any pics of the guts of it?

BTW, the biggest source of error may be the DPMs.  Mine was not very accurate until I calibrated it.

Click to expand...

Thanks for the tips, my DPM (1.733v) was +13mV higher than both of my DMMs(1.720v on both DMMs) when measured a Lith AA, I used the pot to zero in.

knimrod said:

[quote author=chimo link=1204199244/15#21 date=1205772256]Curious here.  Exactly what amp board did kenom use?  I searched and could not find information on it.  Anyone have any pics of the guts of it?

BTW, the biggest source of error may be the DPMs.  Mine was not very accurate until I calibrated it.

Click to expand...

I believe Kenom sawed the amp circuit portion from the PCB the sensor was originally attached to.  Lava posted instructions on how to modify the original circuit to yield 1mV per mW input here.  I think that's the basis for Kenom's meter and it should work nominally.

My 2 DPMs from China are pretty much right on the money.  My DPM from Jewell was off a bit.. Go figure..[/quote]

If that's the case, there really isn't much different between your amp board and kenom's wrt accuracy. Certainly, if one was to be "disqualified" from this thread due to non-calibration, then the other would as well. Even calibrating them to another commercial meter would only get them to the accuracy of the other meter. To make any absolute claims on accuracy, they would have to be sent to a certified calibration lab. For hobby purposes, I'm sure they will do just fine as is.

i own one. i live in hawaii, i got it from kenom, and id be happy to test your laser for you. I dont know why youd want to send it to me oother then if you live in hawaii or something.

laserterd said:

i own one. i live in hawaii, i got it from kenom, and id be happy to test your laser for you. I dont know why youd want to send it to me oother then if you live in hawaii or something.

Click to expand...

do I get a free toaster?

send me your s_ky and i will give you the best toaster i can find.

indeed that thread is exactly how I made my meters. of course there were a few extra embelishes thrown in as well such as the zeroing pot and the other ammenities.

Back on track, y'all. :

I can do basic testing. Atlanta, GA, USA.

I'm in Marysville, WA and can do low and high power (the meter reads up to 100W, but says 50W max) testing on either a scientech 362 or 364, both which utilize a thermal head.

Heh, old thread

I have a laserbee 1000mW. It logs, I've tested it with output verified lasers and it works great, maybe 2% less than actual.

I'm from ACT, Australia