Concerns about recently purchased Scientech 365 + Calorimeter

[ninja_tux]

Hi all,
I recently purchased a Scientech 365 LPM with a matching 360001 Calorimeter sensor. The previous owner had not calibrated it himself, but he said that its readings were always very to close to his other LPMs (namely a Coherent LaserCheck, and a Scientech 364 w/ a 38-0101 sensor head), but he had not used this particular unit in some time. This leads me to believe that it was indeed calibrated to the sensor head at some point, however it has surely been more than 5 years since its calibration.

So I guess my main question is, how accurate will these readings be? I've been reading about LPMs extensively throughout the past week, and now know that, as the equipment ages, its readings will become skewed for a number of factors; as pointed out in Laser_Ben's thread here:http://laserpointerforums.com/f44/word-about-calibration-42140.html
But what margin of error will my readings likely have? I wouldn't want to, say, make reviews with power measurements that are completely off. For example, if I tested my 150mW-rated violet laser with my LPM, would the reading be close enough for me to state it as the "actual" output in a review?

My other question is, is there any way I can make the measurements I take with this equipment more accurate? I obviously know that the 365 can be calibrated, but it seems this requires either controlled conditions with an extremely stable laser, or another LPM to compare to, neither of which I have access to.

I know that there likely aren't absolute answers as to how accurate any LPM is, and likely varies on a case-by-case basis, but any info or suggestions anyone can make is greatly appreciated!

 

[rpaloalto]

Why not ask one of our more distinguished members here at LPF, to professionally measure a few of your lasers. Then you can check them against your LPM, and make adjustments if necessary.

 

[ninja_tux]

Why not ask one of our more distinguished members here at LPF, to professionally measure a few of your lasers. Then you can check them against your LPM, and make adjustments if necessary.

I have considered this, but are normal lasers really consistent enough to do that kind of comparison?

I don't think that the LPM I purchased will be too far off, but if when I receive it (sometime this week) I will test my lasers, and if the measurements seem absurd (ie my 150mW violet outputting 100mW) then I will definitely try to contact someone so I can at least get ballpark figures...

 

[lasersbee]

The only sure way of knowing if your particular LPM is calibrated
properly is to compare it to a known Calibrated LPM...

Other than that you are just guessing... IMO

The "measure your lasers elsewhere to calibrate your LPM" idea
could be used if:-
1) you knew how to calibrate your LPM
2) the other person's LPM was Calibrated recently
3) the returned lasers were not disadjusted/damaged in transport
4) the laser used the exact battery charge as when it was tested
5) the laser was in the same ambient temp as when it was tested
6) and so on and so on...

The best way is the first solution...


Jerry

 

[ninja_tux]

The only sure way of knowing if your particular LPM is calibrated
properly is to compare it to a known Calibrated LPM...

Other than that you are just guessing... IMO

What, in your opinion, constitutes properly comparing it to a known calibrated LPM? It seems this process would consist of either me taking readings of one of my lasers, and then sending it to someone with a calibrated LPM as rpaloalto suggested; or having someone with a calibrated LPM send me one of their stable lasers to compare results with...The latter seems like it would yield better results (I don't trust the consistency of my own lasers haha) but also much less feasible since people generally don't like sending strangers their lasers haha

EDIT: Just read your (laserbee's) edit, and you brought up most of my concerns with the whole sending it someone else and calibrating-through-comparison ...But I guess I wouldn't have any other options since I don't have a recently calibrated LPM...

 

[lasersbee]

That is the problem of buying an LPM that you don't really know is
calibrated...

Comparing it to a Known calibrated LPM will let you know the error
(if there is any) of your LP's readings and you just need to compensate
for that percentage when you take a reading...

The only way of really knowing if your LPM is calibrated is:-
1) get a close-by friend with a known calibrated LPM to come to
your house for calibration tests
2) send your LPM to a friend with a known calibrated LPM to do
some calibration tests
3) buy a calibrated LPM to do calibration tests
4) send your LPM to the manufacturer to calibrate your LPM
5) assume your meter is calibrated and accept the readings


Jerry

 

[ninja_tux]

I suppose for now I will just have to accept the readings I take, knowing that they are likely not entirely accurate. Right now I simply don't have the funds to buy a calibrated LPM like a LaserBee I to compare my readings to. Nor do I personally know anyone with a calibrated meter that I could send my meter to for comparison. I suppose I could consider sending it somewhere to be professionally calibrated, but I'm sure, even if a company like Scientech were to offer such a service, it would cost a pretty penny... *sigh*

Anyway, thanks for the insight! I really do appreciate it

 

[lasersbee]

BTW... I wasn't referring to a LaserBee I....
Your LPM may only be off by a small amount...
Did you buy it from a Member on LPF...
I purchased a 365 from Daguin and it is spot on...


Jerry

 

[ninja_tux]

BTW... I wasn't referring to a LaserBee I....
Your LPM may only be off by a small amount...
Did you buy it from a Member on LPF...
I purchased a 365 from Daguin and it is spot on...

Oh I know you weren't, but it's the only calibrated LPM I could realistically afford and is actually available at the moment ...

I did not acquire it from a LPF member, but rather a former laser enthusiast who has been forced to sell his lasers and meters due to financial troubles. He hasn't used this particular unit in a few years, so I don't know if that makes a difference? Like I said in my original post, he assured me that it had nearly the same readings as his other meters when it was in use...

 

[Hemlock_Mike]

Ninja- Don't panic until you get it and try it. You will likely notice overshoot when the beam first hits the sensor but that too can be adjusted.
I have calibration procedures for this meter and you have a good model sensor head.
Try it before you worry too much -- it is likely a matched meter/head which you are getting.

HMike

 

[ninja_tux]

Ninja- Don't panic until you get it and try it. You will likely notice overshoot when the beam first hits the sensor but that too can be adjusted.
I have calibration procedures for this meter and you have a good model sensor head.
Try it before you worry too much -- it is likely a matched meter/head which you are getting.

+1 for Sound advice from you and Jerry, I tend to be sort of paranoid and assume the worst...a nasty habit of mine haha.

Also, what is the "overshoot" you describe exactly? It's probably good for me to find out now so I don't frantically post about it later in the week

 

[lasersbee]

When you first turn ON the LPM and press the ZERO button.and the
LPM display shows 0.00..
When you put a laser beam onto the sensor surface... the display
will show a high value and within a few second will settle down to
the actual power of your Laser...

Jerry

 

[ninja_tux]

Ohhh ok, I think I've witnessed the phenomenon in videos of LPMs and such, didn't know there was a term for it though! (Though there seems to be one for everything )

 

[lasersbee]

I've only seen this on the Scientec LPMs...

Jerry

 

[ninja_tux]

I've only seen this on the Scientec LPMs...

Jerry

Hmph, that's odd. I guess I'm mistaken then. What about the Scientech meters/sensors causes that sort of phenomenon?

 

[lasersbee]

It's probably the electronics in the Meter...
I'm just guessing....

Jerry