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Could someone let me borrow a laser to test my LPM

brendon7358

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Hi,

I just purchased an Ophir LPM from off-road freak but I am noticing it reads about 5-10% higher than my LPM from Astralist. Anyone in the US with a trusted LPM able to measure a laser and send it to me so I can compare it? I can give a trusted third party the money equal to the value of the laser in case there was an issue. Obviously a stable laser is preferable. I will cover shipping costs.

Let me know, thanks :)
 
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paul1598419

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Did you really expect them to be equal? I have several lasers, but would be concerned about shipping anyone of them and having someone I don't know mess with any of them. There are too many things that could go wrong. Your best bet is to buy a laser that has been measured by a trusted member. But, a 5% difference is within normal limits of accuracy here.
 

hakzaw1

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SELEM -- you should/could have attended and have 50-60 experts with MANY LPMs calibrate yours.
SELEM 2019 year 13!!! mid Aug. in Newton.. hope to see many LPFers there-- after going to your first SELEM it will be impossible to not attend many more-- as well as other LEMs. you are quite 'lucky' to live so close to SELEM its ~17 hr drive for us in Texas. (4 times-and once by AIR 'hated it')
I will bet you that another forum member lives within an hour or so from you!!

Personally I would be fine trusting the results using my Hyperions.. best wishes m8

hak
 

brendon7358

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Did you really expect them to be equal? I have several lasers, but would be concerned about shipping anyone of them and having someone I don't know mess with any of them. There are too many things that could go wrong. Your best bet is to buy a laser that has been measured by a trusted member. But, a 5% difference is within normal limits of accuracy here.
That's the thing, I purchased a 200mW 650nm laser from a forum member a few years back and he lpm'd it around 185mW the hyperion puts it at 186mW but the Ophir puts it at ~205mW. I also metered my laser glow 5mW pen which they said was around 3-4mW the hyperion said 3.8mW and the Ophir says 5-6mW. But I bought these lasers years ago and things change.
 

WizardG

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I don't think either of those meters will do a very good job measuring the 5mW pen accurately. Thermopile based meters like the ones you've tried have a hard time with very low powers.

You said you just bought the Ophir from another member here. When and how was it last calibrated?
 

brendon7358

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I don't think either of those meters will do a very good job measuring the 5mW pen accurately. Thermopile based meters like the ones you've tried have a hard time with very low powers.

You said you just bought the Ophir from another member here. When and how was it last calibrated?
Yeah that's why I measured the 200mW 650nm too. He said he got it a new a few years ago.

Better idea! I will send whoever is interested a couple of my lpm'd pens I'm selling and you can keep them afterwards. I just ask that you pay the shipping since your getting them for free.
 

paul1598419

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That's the thing, I purchased a 200mW 650nm laser from a forum member a few years back and he lpm'd it around 185mW the hyperion puts it at 186mW but the Ophir puts it at ~205mW. I also metered my laser glow 5mW pen which they said was around 3-4mW the hyperion said 3.8mW and the Ophir says 5-6mW. But I bought these lasers years ago and things change.

It is true that neither meter is good for measuring 5 mW lasers. I have a Scientech with an astral calorimeter that can only measure those powers inside an isoperibol. That fact that two meters measured a pointer within 1 mW of each other at 185 mW is likely just a coincidence. None of these meters are that accurate especially since most are calibrated for 1064nm.
 

lasersbee

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Hi,

I just purchased an Ophir LPM from off-road freak but I am noticing it reads about 5-10% higher than my LPM from Astralist. Anyone in the US with a trusted LPM able to measure a laser and send it to me so I can compare it? I can give a trusted third party the money equal to the value of the laser in case there was an issue. Obviously a stable laser is preferable. I will cover shipping costs.

Let me know, thanks
You can't have a laser sent out to be tested and
expect it to read exactly the same after a round
trip across the USA. The Laser will need to be
tested on a recently calibrated Commercial LPM.

What you need to do is send out the OPHIR Head
to be calibrated against a recently calibrated
commercial LPM or send it to OPHIR directly to get
it calibrated.

Then and only then will you have an accurate
referenced LPM.

Jerry
 
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brendon7358

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You can't have a laser sent out to be tested and
expect it to read exactly the same after a round
trip across the USA. The Laser will need to be
tested on a recently calibrated Commercial LPM.

What you need to do is send out the OPHIR Head
to be calibrated against a recently calibrated
commercial LPM or send it to OPHIR directly to get
it calibrated.

Then and only then will you have an accurate
referenced LPM.

Jerry
I know that's the best method but that would be expensive. All I really need is a quick check.
 

lasersbee

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I would trust the OPHIR Head before an
Altralist TEC sensor that was calibrated
using an OPHIR Head. Who knows if Astralist's
OPHIR head has been recently NIST calibrated.

I don't think OffRoadFreak touched his OPHIR
head's calibration. I would ask him.

Jerry
 

brendon7358

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I would trust the OPHIR Head before an
Altralist TEC sensor that was calibrated
using an OPHIR Head. Who knows if Astralist's
OPHIR head has been recently NIST calibrated.

I don't think OffRoadFreak touched his OPHIR
head's calibration. I would ask him.

Jerry
That's why I was suspicious, I figured the Ophir would be more accurate but the other one is closer to the measured values when I bought them. I don't think he changed the calibration either. Someone agreed to send me a laser to test so we will see how it goes.
 

paul1598419

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I still believe both LPMs are within their accuracy tolerances. If you truly want an accurate LPM, I would send the Ophir off to get calibrated. Since it is a professional sensor, it will have the best chance of being more accurate. But, I understand that this is not cheap. Good luck with your experiments. Hope they don't leave you with more questions than answers.
 

lasersbee

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In the Past I received a few Surplus sensors
from some members that were off quite a bit.
Not 100% sure if that was due to someone
playing with the 3 pots inside.

I was able to re-calibrate those 2 heads to
a Brand New Coherent LPM.

Jerry
 




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