*UPDATE* Problem found LPM or Laser

Re: Am I doing this right?

Rivem said:

Don't get me wrong. They're almost certainly the best new meter you can get for the money. I'm not sure what their quality's like since I don't have one, but they're clearly a far cry from the lab grade stuff that can almost guarantee a power level with precision and accuracy. The correction algorithms in the software of newer meters like that will also be pretty complex. Of course, you could probably buy 15-20 very nice lasers for the price of one of the lower end ones.

Edit: Try what I said with the glass of water. It should give an idea of how the meter is corrected when you zero it.

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Hey Rivem,

What exactly do you mean? If I put a glass of cool water behind the sensor and see if it changes?

-Alex

Re: Am I doing this right?

Hap said:

Hey Rivem,

What exactly do you mean? If I put a glass of cool water behind the sensor and see if it changes?

-Alex

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Put a big glass of water with a lot of ice (fairly constant temp) a few inches behind the LPM, give it time to stabilize temperatures, and repeat test as before.

See if it's higher, lower, or the same.

It should give us an idea of how well zeroing the meter actually works.

Re: Am I doing this right? *Video Posted*

My LaserBee meter will not read correctly if its heat sink is placed on top of something which sucks the heat away, he put it on what looks like a piece of aluminum. Maybe if you zero the meter sitting that way it will work, but I'm not sure. I think it was calibrated for the size of the heat sink on it.

Re: Am I doing this right? *Video Posted*

Alaskan said:

My LaserBee meter will not read correctly if its heat sink is placed on top of something which sucks the heat away, he put it on what looks like a piece of aluminum. Maybe if you zero the meter sitting that way it will work, but I'm not sure. I think it was calibrated for the size of the heat sink on it.

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I tried it on Aluminum, yes. I can try that again. I placed my hand right in front of the sensor and it only read as 1mW.....

Tried it on top of a piece of Aluminum, got 120mW.

For pete's sake this is so freaking annoying!

Well it was 120mW, now it's down to 106mW. F*** this. Im done.


-Alex

Re: Am I doing this right? *Video Posted*

Did you zero it while it was on the aluminum? I don't know if the physical coupling would be stable enough that way anyway. It just might not read correctly with a big heat sink under it, I know it makes a difference if I put a piece of paper towel between the heat sink on the sensor and even a wood table, I imagine aluminum would throw the reading off even more.

Re: Done with this S***

Alaskan said:

...the table and the aluminum of the sensor, that will throw the measurement off...

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Would you care to explain how? As I understand it, the entire point of the heat sink is to keep one side of the TEC at a stable temperature. If anything, foam would be worse in this regard.

Re: Done with this S***

Hi,
I would like to help but i never bought laser from any Chinese vendor. I always built my own stuff, And first when i start a build i run the diode in a Labby heat sink fan cooled from a PSU to see efficiency and take a reading. Then when the build is done i check the reading by placing the unit at 6 inches away from the thermopile, focus the beam then back it off a little bit. And my readings are in sync with my pretest readings from Labby. I was going to buy a laser like the PLE-pro but am very skeptical about what they'll sell us over seas. I just can't get myself to buy a laser from those companies. Hey your meter might be working fine if you have a laser you built and have an idea of whats in it to test. Hey i tried just my opinion.

Rich

Re: Done with this S***

You deleted my post for simply pointing out I need Cyparagon to answer why the LPM is acting that way after he was challenging my response that this is what I observed? I didn't see it as aggressive at all, although I did call him the expert which is true, he is far more of an expert than me.

Hap already showed his LaserBee meter behaves that way, mine does too. So, that isn't in question, what I have a question about is why these meters are behaving that way, when their heat sink has another heat sink against them, they read differently. Edit: I believe a big part of it is if the meter is zero'd with, or without, the heat sink resting on another heat conductive surface (or not) and then moved to a fairly good heat conductive surface such as aluminum.

Another thing I am unsure of is whether you can dump power into a LaserBee meter for an extended time without the heat sink becoming more and more ineffective, if it warms up too much, your zero point will be different then. Of course, this would be far more of a problem at much higher power levels than 100mw. I experienced measurement inaccuracies when trying to measure below 5mw, depending upon whether the Laserbee heat sink was resting on a heat conductive surface, or not.

Before someone comes along and tells me that low of a power is outside its ability to accurately measure (spec), I know that, but I found I could get consistent readings at extremely low power if I better thermally isolated the sensor from what it was sitting on. Perhaps the different readings are more pronounced at lower power levels, I know how sensitive the meter can be to even breathing towards the sensor, if sitting close to it, it can jump a couple of mw just from that. Too see how the laserbee sensor behaves at higher power levels I'd need to set up my meter again to see, but didn't Hap just post he saw quite a bit of difference when he moved the sensor off of the aluminum plate? I hope he re-zeroed it when he did that, but he was above 100mw of power and saw a difference.

I agree these observations don't make sense if the heat sink is simply to keep one side of the TEC at a stable temperature, but that little heat sink on a LaserBee doesn't seem big enough to me, there is no way the temperature of the little heat sink won't slowly creep up to throw the T delta off between the two sides of that small TEC and thus the voltage being produced by it as it warms. I will have to try my meter both ways to see, but my stuff is all packed up now, won't be doing that before I leave to go to Afghanistan soon.

Ped, I'm surprised you were affected by my answer to Cyparagon's challenge.

Re: Done with this S***

It's because laserbees are crap shit at best.

Hap I suggest that you get out of this hobby before your OCD literally kills you. You have no ability to troubleshoot these situations which are common in this hobby. Sorry you are having trouble but from now on find something more suited to your condition. You're spending too much money and time on things that ultimately disappoint you. This will be the last time I will be kind to you here so heed my words.

Re: Done with this S***

Alaskan said:

You deleted my post for simply pointing out I need Cyparagon to answer why the LPM is acting that way after he was challenging my response that this is what I observed?

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heh I'm shocked that you're surprised by that. Doesn't matter how much you donate you're still on a shit forum. Doesn't matter how much you praise cyparagon, he will always stab you in the back.

You're a damn fool.

Oh and lastnight I was abducted by aliens. They showed me a good time and asked how Chris Hazlett was doing. I said he's waiting for his second abduction... sorry but looks like your ass is going to get probed again soon because they were drooling. My bad.

Re: Done with this S***

Why quote him?

Re: Done with this S***

The bottom line is, the laserbees are very low tech hobbyist LPMs. They will not do well for reading high or low powers, and yes, a high powered laser will overwhelm that heatsink in short order.

They should be zeroed on the same surface at ambient temperature, and the reading can be thrown off by placement on different surfaces. Which is why it is best to take readings in a consistent way every time.

Arg and Trevor would be the best people to ask about this.

Re: Done with this S***

Very concise way of putting what I wrote several paragraphs to explain!

Re: Done with this S***

It's really interesting, but definitely not worth getting upset or argumentative about. Bad enough one vet left over LPM issues because he couldn't swallow his pride. Probably why Ped is so aggressive in not wanting this thread to be confrontational. (Even if you didn't mean to be.)

Cyparagon said:

Would you care to explain how? As I understand it, the entire point of the heat sink is to keep one side of the TEC at a stable temperature. If anything, foam would be worse in this regard.

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My very poor understanding of it is, these LPMs work by measuring the difference in the rise of temperature. They are calibrated initially on a fairly non thermally conductive surface. Probably a typical work bench.

Having the heatsink on a surface that is either completely thermally isolating, or helps to absorb the heat, throws off the calibration/algorithm that account for the reading.

Re: Done with this S***

Alaskan said:

Why quote him?

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Not sure if this was directed at me or not.

Which is exactly the reason I try to quote the post I'm replying to.

Re: Done with this S***

Somehow I missed that the 1mW drop was every 40 seconds. I must have read it too quickly as I thought it said every 4 seconds.
Haven't used my backup LPM in a long time. Curious to see how much all these things you guys are talking about changes the reading. Mine isn't a laserbee. It was originally built by AWillis a few years ago. One thing I know for sure is my Ophir is consistent and will only give weird readings if the batteries run down to a certain point.
Alex, you get Way too frustrated WAY too quickly. I haven't seen any proof so far that there is anything wrong with that unit. Just as others have pointed out there are a LOT of potential reasons why your reading could be wrong. Yes it could be exactly as you are measuring. I think there are more of us leaning towards a wrong reading because a lower output isn't consistent with Jetlasers units and there are a lot of factors that can interfere with that Laserbees readings because of its design although I'm quite surprised at how badly some are saying theirs are and believe those issues are more of a bigger factor as the laser output goes up. What I mean is the higher the output of the laser you are measuring the higher the error will be although from what I am reading on the laserbee site that is supposed to be taken into account by his software. Don't know if he calibrated each individual one though or if all of them get the same software (which is more likely). Anyone know if the coating on the sensor plate is done by hand and how much readings are affected by its thickness?
Anyways, I'm worried that you take this stuff too seriously. It's not healthy to get so worked up about what is supposed to be a fun hobby. Perspective! Lasers are finicky pesky critters and go into the pile of wants and not needs. They are not clothes, food or shelter and should not affect your health. Relax and get some fresh air. Read your Bob M quotes and take a break.