Power Meter Calibration and Comparison

Alright, I'll update once I get the parts.

need an estimate for parts too so we can add it to the total.

Kenom said:

4. You can solder the driver to the wire.  that really doesn't make any difference.  Make one less step for me trying to figure which wire is neg and Pos. (not that this is hard.)

Click to expand...

you probably already considered this, but just in case:

Will those drivers fit thru whatever sort of hole is going into the butt of the laser housings?
("just in case" - or out of case, as you will)

aaack...
I just noticed that my last post is full of potential verbal abuse, which discretion advises me not to point out...

But I will clarify what I meant: if the board gets soldered to the cable before insertion, the hole at the tail end of the laser body must be large enough to accommodate not only the cable diameter but the width of the board too. But you knew that. ;-)

Kenom said:

need an estimate for parts too so we can add it to the total.

Click to expand...

Mouser parts = $9.85 + $6.85 S&H

AC adapter = don't really remember... bought it from a Radioshack going out of business, retail price is $27.99, but I probably paid ~$10.

Drivers (2x adjustable) = $20

other parts + wire = negligible

Shipping to Kenom = probably ~$5

Dunno if you want to include the cost of shipping from the Mouser stuff or to you, Kenom, so you can add it up however.

danq said:

aaack...
I just noticed that my last post is full of potential verbal abuse, which discretion advises me not to point out...

But I will clarify what I meant: if the board gets soldered to the cable before insertion, the hole at the tail end of the laser body must be large enough to accommodate not only the cable diameter but the width of the board too. But you knew that. ;-)

Click to expand...

He already stated that the tailcap will not be used, and the hole in the back is wide enough to fit a 10440 battery, so that should be enough for the board.

Seeing that the physical part is progressing so well, what about putting some effort in the non-physical part?

I still haven't received any feedback on the calibration instructions which I posted a while ago. I have heard some hints and tactics that can be incorporated (like measuring multiple times to get an idea of the standard deviation, and recording every and all measurements in a shared log)

I suggest we break the instructions up into pieces (which it basically already is) so that each piece can be designed and refined apart from the others.

Take a second look at my post with instructions and tell me what's wrong (there is always something wrong with a first draft) If it's too detailed then that is okay too, an we need to simplify it.

Ok and I'm looking at $40 for the hosts, and $40 for the diodes. Include the price of your components and that's $51.70 I'm including my heatsinks and the tripod for free. Brings us to a total of $140 including shipping to Jayrob the first on the list.

Zom-b, I was very impressed with your procedural breakdown and as far as I can see, they are perfect. Multiple measurements following those procedures will net us some solid readings with no other factors.

Yes the laser end is large enough to accomodate the driver attached into the barrel.

Jayrob,  (paid Thanks!)
Daguin  (paid thanks!)
Zom-b (Paid Thanks!)
IgorT (Slovenia)  (paid thanks!)
Rckstr. (Paid Thanks!)
danq   (paid thanks!)
muledeer
happytomato (Uk.)
Gooeygus.
Scopeguy  (paid thanks!)
pullbangdead (Paid Thanks)
pseudonomen137
Hydro  (paid thanks!)
Dr. Lava (paid Thanks!)
 
Total 13 participants.

Payment required from each $13 (including paypal fee so that doesn't get lost)  Payment can be made to kenkassidy@hotmail.com

Hello from Big Bear guys!  Kenom $13 sent, let me know if there is need to change amt.  Thanks!  Best Wishes!  -Glenn (AKA scopeguy, scopeguy20, LG GB dude etc.)

Sorry I overcaculated the fee's for paypal. Payment needed is only $10.35

Sorry guys I'm not going to be able to participate in this comparison test, please remove my name from the rotation list, my apologies.

Hi guys, Kenom just pointed me to this thread. First off I want to say this is a great idea. Even though I have calibrated thermal meters it will be fun to test just to see what everyone else is getting.

For the lasers, you seem to have pretty much everything worked out. I agree with Igort the 803 shouldn't be run at 100mW, try 60-80 mW. You really don't want that diode drifting because it's aging fast due to being over-driven.

Factors to control: temperature of the laser is paramount. You've got this covered.
Temperature of the DRIVER is also important. One of the reasons the micro flexdrives are so stable is because they don't heat up much. Heat causes drifts in semiconductors and resistor values, and all that results in a drifting current source driver, even if on paper it looks just as stable as any others. So, if you use a rckstr (which is OK with me), we should allow plenty of time for the driver to reach final operating temperature before doing tests.

count me in!

^Lose one, gain one. That works out ok, I reckon.

Sorry you couldn't go along, electron. Was it something we said?

I'm also glad this got up to where it's only $10 each, that was kind of my limit on my funding at the moment. Thanks for joining up everybody!

As an aside: We had a group meeting yesterday for my research group, and the importance of power meters, even at the level here, became clear at this meeting. They were discussing the pulsed measurements that are done often for devices, and how not all meters are created equally, ESPECIALLY when trying the measure high-powered lasers with pulsed drive. You have to get a sensor fast/sensitive enough to pick up the power and measure the actual peak it in the short duration of the pulse, and yet not so sensitive that it saturates and doesn't show all the power. Turns out, one of the grad students did a new test/comparison with some new information and new data, and it turns out for the longer pulses being done in his research, the meters in the lab were up to a factor of 4 different from one another! The one he had been using was saturating, and was about a factor of 4 too low. These meters are/were being used to measure and formulate data to publish, and it's really important that the measurements be accurate, hence the concern. I'm not using any of these meters, and the complications of pulsed measuring doesn't come into play here with what we're doing (necessarily). Just goes to show how, at all levels up to and including top-of-the-line research, you have to be careful with measurements to make sure the data coming out of a tool is really telling you what you think you're reading from it.

Good thinking...

I could add on a small heatsink to improve the temp a little... also, since we're using a fixed voltage AC adapter, we could probably use a few diodes in series at the input to drop some of the excess voltage so the driver doesn't generate as much heat.

With the heatsink, I don't really know what size of the inside of the host will be, but what I was thinking should fit within a 15mm diameter. And the diodes could be added on my end or Kenom's end if we wanted to do it.

Inside diameter of the barrel is 17.08mm.

heatsinks are WONDERFUL ideas.  I utilize them myself on your load circuit.  Since them babies heat up so much.  it's ABSOLUTELY necessary. This particular gem is a Ram heatsink for a video card. Adhesive backing means not so efficient as thermal epoxy but still works very well. Under full load (450ma) this thing is still safe to touch.