Power Meter Calibration and Comparison

[Kenom]

Well, if we go for a "box" I don't have the means to assemble the rectumfyer and all taht other stuff.  I would then recommend that rckstr or someone else be the headman, since he has most of the parts necessary.  Nor would I be able to throw a heatsink on (jayrobs would work best for that) or a DX red module with a different diode.  Might as well throw a TEC in there ta boot (I can donate that or psuedo can) to keep the "module" tempurature regulated.  

I really dont' care so long as I get to play too. LOL

PLus. I have this I can donate for a key switch.

 

[danq]

? but why does it matter if the box shakes abit at power on/off? the measurement isn't like a camera shutter, it's a relatively steady-state for an indefinite period while the operator looks at it. It could jump a whole meter as long as it lands within the grasp of the op, who then merely aims it at the correct place and takes a reading. No?

PS: hey Igor, check your email!

 

[danq]

Kenom, how did you do that? I swear when I last posted, yours wasn't there!

that's not the kind of key I meant - but in the spirit of military contracting, that's a good idea to have too. We're gonna need a grant for postage!!!

 

[Kenom]

haha, it was a normal post I added the picture after.

 

[hydro]

I vote for the box and cord so we do not have to open it up or worry about what type of battery or if it is charged.

 

[IgorT]

? but why does it matter if the box shakes abit at power on/off? the measurement isn't like a camera shutter, it's a relatively steady-state for an indefinite period while the operator looks at it. It could jump a whole meter as long as it lands within the grasp of the op, who then merely aims it at the correct place and takes a reading. No?

PS: hey Igor, check your email!

Well, if the box would sit firmly on the table (rubber feet?), in front of a meter, it wouldn't shake as much as a pointer would, during switching it on or off... So while a remote switch would be a further benefit, it wouldn't be as important as with the pointer, where it would be harder to include anyway.

But the aim should still stay the same through the (three?) measurements, everyone will make. With thermopiles, the reading changes a little if the beam is not on the center. And Jayrob noticed it changes even more on his optical meter.


Most people know how to do it right. So they will get the right results no matter what. But if someone is less experienced with their meter, this would give them more consistent results. It's not the most important thing tho. But it is how it would be done in a lab.


P.S. I just did, and i still don't see anything.. :-?
Can you send again?

 

[IgorT]

Might as well throw a TEC in there ta boot (I can donate that or psuedo can) to keep the "module" tempurature regulated.

Do you have a constant temperature Peltier driver?

I have some high efficiency constant temperature TEC driver ICs. I wanted to put them together for a while now, but the circuit is so complex, that i have no idea when i'll even have time to do it...

Without a constant temperature driver, that adjusts the heat pumping power, the TEC would cause the temp to drift one way or the other all the time.

Since the diodes will not be driven too hard, and the measurements will be short, a passive heatsink should be more than enough. The only variation is going to come from room temperature, but if people wait for the temp to be close to what it was in the original measurement (or move into a cooler/warmer room, like Zom-B suggested), this won't be much of a problem.


Unless someone already has a working TEC driver, we should skip this part, as it'll take too long to make it.

 

[Kenom]

I agree. TEC is hard to integrate. Just throwin it out there.

 

[IgorT]

Yeah, i mean i would love to have a constant temperature setup for experiments, especially an experiment like this..
I want to build a couple constant temp TEC drivers when i have some time.. But you should see those regulators!


Check out the picture.. The thing on the left is my entire boost driver for blu rays (more parts on the other side). The regulator is the tiny black square (3x3mm). The thing on the right is just the regulator for a constant temp. TEC driver. Also SMD, but almost as big as my entire driver, because it's so complex and has 28 pins!


Making the blu ray driver takes me quite a bit of time, because everything is so small. Making the TEC driver would be a project by istelf! I want to do it, but i have no idea when i'll manage.

 

[pullbangdead]

Another idea to remove variables: Anybody want to make an APC driver? That is, assuming the 3rd pin on the PHR is a photodiode. I've never read if it is or not, but it is soldered to in the drives. Meredith has a $15 APC driver kit that should fit in a box nicely. I don't know that it will work or not, but maybe it would, or if anyone has an APC to hook a diode up to and try it (if they're willing to risk the diode, that is). This would take out all temperature and environmental effects on the laser diode output, at least. Anybody?

That's 4 of us right here in California! You, hydro, daguin, and myself!
Jay

Actually 6 in California, at least: scopeguy is in the LA area, near Chino Hills (from thread in Off Topic), and I'm in Santa Barbara.

 

[daguin]

[quote author=jayrob link=1217029972/120#137 date=1217476863]
That's 4 of us right here in California! You, hydro, daguin, and myself!
Jay

Actually 6 in California, at least: scopeguy is in the LA area, near Chino Hills (from thread in Off Topic), and I'm in Santa Barbara.

We're taking over the whole world [smiley=evil.gif]

BOW before the Gold Coast contingent!

Peace,
dave

 

[pullbangdead]

::Too excited to explain::

I can use a meter in the lab that one of my officemates works in.  It's not my groups lab, but their laser lab is very well equipped as well.  Specs for the meter I can use: Newport 1835-C optical meter (http://www.spectroscopic.com/Newport/1835-C_datasheet.pdf) with an 818-UV detector (http://www.newport.com/file_store/PDFs/tempPDFs/e2882_Low-Power-Detectors-Legacy-818-Series.pdf).  Need to look into it further to make sure I'm doing things right while I'll be using it and to see how accurate I can get with it, but best I can tell it's a $2000+ metering set up.  I'm in business!

Also in this lab, just for starters, they have a Coherent 5W 532 DPSS, and a nice little 193nm excimer laser.  Too bad it's not my lab, but I may end up using some of those other things from time to time for testing and such.  But for now, I've got the Newport at my disposal (as long as I'm not trying to use it too much).

 

[danq]

That's 4 of us right here in California! You, hydro, daguin, and myself!
Jay

Actually 6 in California, at least: scopeguy is in the LA area, near Chino Hills (from thread in Off Topic), and I'm in Santa Barbara.

We're taking over the whole world  [smiley=evil.gif]

BOW before the Gold Coast contingent!

Well... I'm a Left Coaster all the way, but... a Northern Californian - let's keep that clear! ;-)

DanQ

 

[IgorT]

Another idea to remove variables: Anybody want to make an APC driver?  That is, assuming the 3rd pin on the PHR is a photodiode.

APC would be THE best option, much better than temperature regulation.. Unfortunatelly the diodes we use never have a photo diode.. It would require an external one and again make everything too complicated, because of the optical setup..


Passive heatsinking is gonna have to be good enough for our purposes. And if the measurements are kept short there won't be much of a problem.

 

[danq]

::Too excited to explain::
But for now, I've got the Newport at my disposal (as long as I'm not trying to use it too much).

That's great! When you get a turn at the one we're passing around, your measurements with that setup may be the ones that we use as the 'true' values.

If that's the case, maybe you should do a before-passaround measurement and an after-passaround? Kenom should still do both ends too, imo, so we can compare those readings too.

DanQ

 

[IgorT]

::Too excited to explain::
I can use a meter in the lab that one of my officemates works in.

Hehe, great!

If the meters are good enough for your university, i think they should be good enough for establishing a baseline for this experiment..

But does your lab have thermal meters too?

If that's the case, maybe you should do a before-passaround measurement and an after-passaround? Kenom should still do both ends too, imo, so we can compare those readings too.

The "baseline meter" should definitelly be at the beginning and at the end.