Power Meter Calibration and Comparison

IgorT said:

It's an electronics problem Dave. You may not see it, but the 75mW limit is physically impossible with a fully working driver. And the driver is the only thing keeping the current constant, and the power somewhat constant.

And it is possible to check for regulation without taking the laser appart. I described how in my previous post - the current is measured and the input voltage varied. If the driver is in regulation, the current will stay the same. Since this is a linear driver, the current can be measured between the PSU and the laser.

And i only recommended a driver transplant IF there is a problem - as in the driver not being in regulation / a blown capacitor bypassing current / random unknown problem. If so, it invalidates the tests done so far anyway.


If we do the testing after Europe, we have to repeat everything. The problem can be tested for without invalidating the testing by:
- Measuring the power
- Changing the temperature of the laser, and remeasuring the power
- Observing the beam profile for mode-hopping
- Measuring the current, while varying the input voltage from a variable PSU
- I don't know how to check for a blown cap (which could bypass some current even if the driver was regulating), without opening the laser, however Kenom's first power measurement would show this.

All of this can be done by Kenom.


I'm hoping you have a variable PSU, Kenom?

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And mode-shifting, while varying the input current with a variable PSU (use additional lens so not to dislodge the glued lens)

The pre-test and post-test will tell us if some extraneous variable was missed.  That is what they are for.  Since a question has come up, then an added mid-term test may tell us now if something has changed.  However, I still believe that DOING anything to the driver will invalidate the experiment and require a restart.  "Measuring" the current, is not "doing" something to the driver.  However, how does one "check for regulation" without altering something?  I disagree that we could replace the driver (or any part of the driver or re-adjust the driver) and still remain valid.  Any alteration of a significant component of the experiment will invalidate the results thus far.

Peace,
dave

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I agree with Dave... if anything.... anything... is adjusted...
changed or... even just a connection unsoldering and resoldering on the
405nm "test standard" it will invalidate the test results to this point.

You don't touch a test standard after a test has begun... unless you restart
the test...

This should have been a blind test with no one (or perhaps only one person)
knowing the tests results as they came in... IMHO

I'm not involved in this "Power Meter Calibration and Comparison" event...
but I've been following it from the beginning...    Just my 2 cents..

Jerry

Sure, but the standard has to be a standard.
Measuring the current, and all of the other tests are NON INVASIVE. They don't change anything if done like ZomB and i recommended. They will just make sure that the standard really is what it should be.


Besides, lasers and meters are not humans. They don't suffer from placebo effect.

Without getting to overly complex, wouldn't it make sense that if the test lasers went back to Kenom before Europe, and he measured the power to be the same or close, that the experiment could continue?

Even though there might be a suspected problem with the driver, if it measures the same for Kenom, I think they could continue to Europe...
Jay

I think the experiment should continue as plan and the laser should not be touch. If any thing is change or touch the experiment has to start over again. The only reading that is really off is from Kenom, every one else are close. If it goes back to Kenom now what would be the point? If the readings are all over the place then yes it should go back to have it check out but they are not. For this reason it should continue then sent back to Kenom at the end.

umm...

scuse me, but I think you're all spinning your wheels unnecessarily.

We will know so much more after I do an 80 degree test, and after Kenom re-measures them.

If I find that temp made the difference, then we'll know that temperature is critical for this driver/diode pair.

If Kenom finds that the 405nm is putting out 65mW instead of 75, then (a) the driver's whacko or (b) Kenom actually set it to 65 (ie he's whacko).

but until we get that data, it really doesn't matter how many angels are dancing at the focal point...

I'm back early; will do the measurements Saturday or Sunday.

DanQ

what the heck - I can dance too...

IgorT said:

It's an electronics problem Dave. You may not see it, but the 75mW limit is physically impossible with a fully working driver.

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unless the pot is faulty? or has bad connection?

And it is possible to check for regulation without taking the laser appart. I described how in my previous post - the current is measured and the input voltage varied. If the driver is in regulation, the current will stay the same. Since this is a linear driver, the current can be measured between the PSU and the laser.

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agreed.

I'm hoping you have a variable PSU, Kenom?

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I'm hoping it doesn't come to that! if so, he'd better do that test very carefully!

all in all, it would be best to leave it like it is, if it appears stable - and so far that seems to be the case.

but if it's not regulating, then I'd have to ask: is the european input voltage going to be different??

The european voltage will be different only going into the power supply.  It's a regulated psu so that's not going to make any difference as the output voltage is still going to be the same regardless of input voltage (as long as nothing is broken in it)  

As such, the only errant reading that hasn't been in synch thus far has been my initial reading.  We can verify the lasers "integrity" by 1. doing a longer test and seeing if it sags or changes any.  That would indicate a consistent regulation to me.  2. by doing another reading from me at 75 degrees and see how that changes the reading on my meter and also allows me to see if I didn't mess up in my initial reading and misrepresent the initial power of the laser even at 80 degrees.  

by sending the laser to me prior it will also give those before an indication of the meters they have's ability to accurately read this laser.  Essentially by sending the laser back to me, it's completing the experiment thus far for those that have participated in it.  Not necessarily changing anything in the laser itself just verifying that the readings are close or the same as when I shipped it out. thereby ending the experiment as it was intended.  Then all those that have participated prior to this point can take the data and use it as was intended.  It won't nullify the experiment.  We just start it over again for those in the european countries.  I really hope that makes sense.  Nothing really seems amiss with the readings thus far cept mine.  They seem to be pretty consistent and where we would expect them to be with meters that are within 5% accurate.

It doesn't seem to me that it's out of regulation, just broken thus that prevents it from going above a certain current.  If when I get it and test it and it is at closer to the readings that everyone has gotten, we can start investigating the driver and potential issues with it.  I do have a variable psu and can change the input voltage to test at that point if it's only in the particular psu does it remain in regulation since it's a regulated psu.

I can understand dave and everyone's concerns up to this point and it's not necessarily something that is going to nullify the experiment as long as the laser stays at the same output.  Yes we have a variable in everyone's meters and it was to try to determine the variable that we created these lasers.  So far, it doesn't seem that the laser is a variable.  We will see though when it gets to me and is, as I think ,going to be right with everyone's readings thus far.

If however, it does appear to be way off from my initial readings or is nowhere near everyone elses readings, I will repair the laser with a "new" rckstr driver, and pay to ship these back to the initial participants to get us back up to speed.

IgorT said:

Sure, but the standard has to be a standard.
Measuring the current, and all of the other tests are NON INVASIVE. They don't change anything if done like ZomB and i recommended. They will just make sure that the standard really is what it should be.


Besides, lasers and meters are not humans. They don't suffer from placebo effect.

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Murphy's law is a generalization of the placebo effect towards non animate objects that still have health and can die (figuratively).

danq said:

umm...

scuse me, but I think you're all spinning your wheels unnecessarily.

We will know so much more after I do an 80 degree test, and after Kenom re-measures them.

If I find that temp made the difference, then we'll know that temperature is critical for this driver/diode pair.

If Kenom finds that the 405nm is putting out 65mW instead of 75, then (a) the driver's whacko or (b) Kenom actually set it to 65 (ie he's whacko).

but until we get that data, it really doesn't matter how many angels are dancing at the focal point...

I'm back early; will do the measurements Saturday or Sunday.

DanQ

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I think you may have some catch up reading to do. We've already moved past that point. If the diode is in a kink, then it will prove that it is very temperature dependant, and we don't have to do explicit temperature measurements anymore.

If you have a variable PSU at your disposal then it would be ideal, then you can make a graph. Just try not to go past the current the driver is set at to prevent optical degradation. If the driver is regulating, you wouldn't be able anyway, but we don't know that at this point. So, measure the current with *your* ampere meter when powering it with the original power supply first.

danq said:

I'm hoping you have a variable PSU, Kenom?

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I'm hoping it doesn't come to that! if so, he'd better do that test very carefully!

all in all, it would be best to leave it like it is, if it appears stable - and so far that seems to be the case.

but if it's not regulating, then I'd have to ask: is the european input voltage going to be different??

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Testing it with an external PSU does not invalidate the experiment because it doesn't change anything to the driver or laser (if done right)

Danq, can you do the graph testing? Depending on the results we may or may not even have to send it back to kenom.
If it turns out to be out of regulation, the experiment is nullified
If the regulated current is in a kink, the experiment is nullified
If not, we'll discuss further actions.


I'm also thinking of yet another simple test to see if it is in a kink. Hold a lens in front of the laser while it is on and observer the spot. If it is clean TEM00, it's ok, but if it is slightly to the side (not in the middle) or worse, the diode is either in or after a kink. (more testing required)

Kenom said:

The european voltage will be different only going into the power supply. It's a regulated psu so that's not going to make any difference as the output voltage is still going to be the same regardless of input voltage (as long as nothing is broken in it)

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I can test if the PSU really performs the same for 100V or 230V. I have a variac at home. It's not capable of 60Hz though.
I can also use my oscilloscope to see if there is any ripple from the 50Hz present in the output. If built improperly, it may suppress 60Hz ripple but forget about 50Hz. (or no suppression at all, which I can not test for)

Maybe IgorT can do the same, as he's before me?

I wouldn't think there is a problem from the power readings alone. I even said, that the readings alone look good. But then i realized something.

How come Scopeguy measured "correctly"? His reading should be higher than Kenom's! 6% higher, to be precise...

Did Scopeguy use the correction factor i gave him once? <------- This is an IMPORTANT question.

Scopeguy consistently always measures 7% more than me. I know my meter is 2% above Electrons and Kenom's is around 3% above it. So Scopeguy should measure 6% more than Kenom.


The readings alone would seem to be fine, even with Kenom measuring more, but Scopeguy's reading + 75mW limit is what has me worried.


If you guys are all willing to repeat the whole thing if it should turn out at the very end, that there was a problem, i don't have a problem with it.



However! Once the package leaves the US and goes to EU, the first recipient in EU might have to pay duty fees and taxes on it. Importing can cause dificulties. Importing twice is even less fun.

- I thought ZomB was the first EU recipient, now it would seem it is me.. At the start i said several times it can't be me. We have the most anal customs in the known universe. I'm gonna have to fake an invoice and a credit card recepit to proove i paid, what i didn't pay, in order to pay custom fees and taxes on what i didn't pay.



A simple measurement by Kenom can proove this one way or the other. A simple non invasive current measurement can proove the presence or absence of regulation. Measuring the current can be done between the PSU and the cable, and does not influence the laser in any way.


Altho, if DanQ tests for temperature dependance and kink possibility, and prooves current regulation, the experiment could proceed as planned without interruptions.

DanQ is more than qualified to check for regulation safelly. Again, it's a non invasive procedure, because we used a linear driver. By putting a meter between PSU and laser cable, current regulation can be prooven.

If the driver is regulating and the diode isn't kinky, then there really is no need for Kenom to redo the measurement until the end.

IgorT said:

- I thought ZomB was the first EU recipient, now it would seem it is me.. At the start i said several times it can't be me. We have the most anal customs in the known universe. I'm gonna have to fake an invoice and a credit card recepit to proove i paid, what i didn't pay, in order to pay custom fees and taxes on what i didn't pay.

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I thought I said at the beginning that the dutch customs check about every package bigger than an envelope since some terrorist thing regarding America (don't remember what)

hmm, I just looked up the current regulations on the customs website, and it says that I don't have to pay taxes for anything marked with less than €22. It doesn't say anything about them searching the package for illegal content.

That's right. The original first EU recipient was Happy, from UK..... That's why i said i'm glad i'm not the first one.

In Slovenia, marking packages with low value doesn't help.. They open everything that looks big or has postage more expensive than $3. And then they want an invoice..

I have to fake credit card statements to proove i paid what i didn't pay, to pay custom fees on that to get somethign released, that was shipped to me as a gift!



Anyway, i have come to accept being tortured by our customs. I am used to it, i expect it. But i really don't want to do it twice for the same thing. It wouldn't be the first time! They even want to make me pay when i get something to repair!

Then what if you DO get something as a gift, can't you tell them it's a gift? Can't you tell them you know nothing about a shipment at all, as if someone sent it as a surprise?

Zom-B said:

Then what if you DO get something as a gift, can't you tell them it's a gift? Can't you tell them you know nothing about a shipment at all, as if someone sent it as a surprise?

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I have gotten gifts, that were stuck at the customs for weeks. I once received a broken box laser to repair, and it was stuck there for weeks, untill i sent them links to places where the parts were bought, pretending i made it for the sender and he is sending it back for me to fix it - that took two weeks..

I often buy things worth hundreds of dollars and have them shipped with the cheapest shipping available, just to reduce the chances of our customs opening it! When they see a box, they get excited instantly. If the envelope is too thick, they open it up, and if the contents are three broken pieces of random stuff they ask for an invoice. It's driving me crazy. Every single DX envelope comes to me opened up and sealed with their tape.

When i get something for free, i send the sender a fake invoice to print and include, showing a low price (<$30)... And that's when they often ask for a credit card statement.

When i get something for free, it's the worst, cos then i have to make up and fake paperwork!


This is why i would rather not have to do it twice, if it can be avoided.... :-/

does it matter if it comes from a european country or just the united states? Because I know that happytomato would be happy to pass it on from him so taht this doesn't happen if you don't get nailed from european countries.

IgorT said:

[quote author=Zom-B link=1217029972/620#636 date=1226801567]Every single DX envelope comes to me opened up and sealed with their tape.

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Well, I've never had that, and also a THICK envelope with 12 sleds from amkdeath also received without a problem. I guess my customs isn't so bad after all.

Kenom, DX is not the united states

I guess the best option if to send it to me so I can send it to IgorT next