Are Laserbee's as accurate at higher powers?

Hap said:

Hey guys,

I did another run and got an output between the high 2500mW to the low 2600mW so about 100mW's above spec. Do you think the previous owner simply had peaks when he recorded 2.8 & 2.7W's? So what it averages on output is what im getting?

-Alex

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You might want to consider purchasing a fresh/new sensor form Laserbee if you caused smoke to come out of yours and consider testing a more rational way as Seoul_laseers suggests "The laser output should more or less cover the sensors surface (50-90%). (defocused) and centred."

Is hard to figure what you are trying to determine and why.
Questions about the seller that nobody can answer --If you want to know why your LPM reading and the sellers readings are different you can guess. Different time different place different conditions , different LPM and so on. Why don't you just email him and ask + see if he has the original test data and spec details that came with your MGL-F-532 2.5W--if not email CNI and see if they can email you a copy of the test data/spec for that particular serial number--then you would actually know what you have or at least how it started out in life.

Encap said:

You might want to consider purchasing a fresh/new sensor form Laserbee if you caused smoke to come out of yours and consider testing a more rational way as Seoul_laseers suggests "The laser output should more or less cover the sensors surface (50-90%). (defocused) and centred."

Is hard to figure what you are trying to determine and why.
Questions about the seller that nobody can answer --If you want to know why your LPM reading and the sellers readings are different you can guess. Different time different place different conditions , different LPM and so on. Why don't you just email him and ask + see if he has the original test data and spec that cam with the lasers--if not email CNI and see if they can email you a copy of the test data/spec for that particualr serial number--then you wold actually know what you have or at least how it started out in life.

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Okay,

I spoke to CNI and they found the unit with the serial #. However, since the purchase was made to them too long ago they have no records of it. I asked if a 2.5W unit performing around 2.6W's would be normal and she said yes which makes sense.

I will probably invest in a new LPM too

-Alex

Hap said:

Hey guys,

I did another run and got an output between the high 2500mW to the low 2600mW so about 100mW's above spec. Do you think the previous owner simply had peaks when he recorded 2.8 & 2.7W's? So what it averages on output is what im getting?

-Alex

Click to expand...

Possibly, or he was just in a thermal environment that suited this laser a bit better.

I would not wory much about it at all, if the laser produces a nice single mode beam, it doesn't matter that much if it is 2.5 or 2.7 watts, as long as it is stable.

A difference of 10% in output power is hardly noticable. I understand you want to get what you paid for, but would you have skipped this purchase if the stated power was 100 or 200 mW less?

It's also feasible that the vendor had a LPM that was off a bit in the other direction (indicating too much power) when getting those readings. Which such a small difference i would not assume any ill intentions - it's not like they are marketing a 50 mW laser as a 200 mW one while it doesnt even draw enough electrical power for that to be possible

Benm said:

Possibly, or he was just in a thermal environment that suited this laser a bit better.

I would not wory much about it at all, if the laser produces a nice single mode beam, it doesn't matter that much if it is 2.5 or 2.7 watts, as long as it is stable.

A difference of 10% in output power is hardly noticable. I understand you want to get what you paid for, but would you have skipped this purchase if the stated power was 100 or 200 mW less?

It's also feasible that the vendor had a LPM that was off a bit in the other direction (indicating too much power) when getting those readings. Which such a small difference i would not assume any ill intentions - it's not like they are marketing a 50 mW laser as a 200 mW one while it doesnt even draw enough electrical power for that to be possible

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Thanks Benm

-Alex

I looked at the LPM the seller was using to test your Laser.
It s a SYNRAD PW-250. Here is the Manual....
http://www.synrad.com/Manuals/pw250v2.pdf

It is a 250 Watt meter that has a +/- 5% accuracy when new
and a resolution of 100 mW.
Looking at the picture the LPM's casing it has seen a lot of use
although I have no clue as to when it was last calibrated.

On page #2 of the Manual it states that when Zeroing the LPM
a reading of -0.300 Watts to +0.300 Watts is good enough...
That is worrying....
What was the PB-250 reading at no input before your Laser was
tested for power ??

At worst case with a "calibrated" PM-250 the readings at 2.8W
could be off by (5%) 140mW plus the 100mW of resolution plus
perhaps a non-zero start point.

If the PM-250 was off the claimed 5% accuracy.. that number
could even be worse.

If your LaserBee AX Sensor has a small burn mark it will still
be accurate if you increase the beam to cover most of the
sensor.
A small burn would not effect the reading unless the reading
was taken on the spot with a small beam diameter.

With a Wafer Type (TEC) sensor it is not necessary to precisely
center the beam being read. Centering the beam on the sensor
is however required by a Radial Type sensor such as the OPHIR
sensors.


Jerry

Jerry, just curious, why is it more important to be centered on the Ophir type sensor than the TEC type unit?
I'm sure that this has been covered before, and I actually think I remember a thread where readings were taken on an Ophir sensor at different positions, resulting in slightly different values.
I have an Ophir sensor, and when testing, I have always tried to be as centered as possible, and use 50%~75% of the sensors surface area to have consistant readings and to prevent burn damage.

BowtieGuy said:

Jerry, just curious, why is it more important to be centered on the Ophir type sensor than the TEC type unit?
I'm sure that this has been covered before, and I actually think I remember a thread where readings were taken on an Ophir sensor at different positions, resulting in slightly different values.
I have an Ophir sensor, and when testing, I have always tried to be as centered as possible, and use 50%~75% of the sensors surface area to have consistant readings and to prevent burn damage.

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Yeah, the resolution/accuracy on those LPMs isn't great. Fine if you're using it to test big CO2/YAG etc. lasers in the field (as is the intended purpose of those), not so good for "lower power" lasers like Hap's though.

Ahhh, so my LPM was right all along?

-Alex

Hap said:

Ahhh, so my LPM was right all along?

-Alex

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I'd say so - I was actually considering getting one of those Synrad LPMs but they're just not accurate enough for the low end Class IV stuff. They aren't even designed to measure <1W.

diachi said:

Yeah, the resolution/accuracy on those LPMs isn't great. Fine if you're using it to test big CO2/YAG etc. lasers in the field (as is the intended purpose of those), not so good for "lower power" lasers like Hap's though.

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Thank you sir!

diachi said:

I'd say so - I was actually considering getting one of those Synrad LPMs but they're just not accurate enough for the low end Class IV stuff. They aren't even designed to measure <1W.

Click to expand...

Low end Class IV!

-Alex

Hap said:

Low end Class IV!

-Alex

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When your LPM is designed to measure 1W up to 250W, then 2.5W is the low end of Class IV. I've seen these little LPMs used on Laserscopes doing 40W 532nm, that's more what they are intended for. :crackup:

Low end of class 4, that's a serious LPM.

BowtieGuy said:

Jerry, just curious, why is it more important to be centered on the Ophir type sensor than the TEC type unit?
I'm sure that this has been covered before, and I actually think I remember a thread where readings were taken on an Ophir sensor at different positions, resulting in slightly different values.
I have an Ophir sensor, and when testing, I have always tried to be as centered as possible, and use 50%~75% of the sensors surface area to have consistant readings and to prevent burn damage.

Click to expand...

That was discussed on a Thread a while ago...
The OPHIR Radial Sensor has Thermocouples around
the perimeter of the Sensor disk.
If a Laser beam is exactly in the center of that disk
(Thermocouples ring diameter) all the thermocouples
will sense the same amount of differential heat at the
same time giving an good reading since it was calibrated
that way.

If on the other hand the Laser beam was not centered
on the sensor... some of the thermocouples will sense
different amounts of differential heat at different times
and skew the actual readings.

I did some tests and took reading on that Thread.
I've attached a copy of the image...

Jerry

Jerry, thanks for the explanation, I remembered that thread, but couldn't remember the reasons for needing to have your dot centered. :yh:
I believe it's probably a good practice to do this with any sensor, especially since you want the whole dot to fall on the sensor surface for the most accurate readings.

Edit: After looking at those reading in your thumbnail pic, I noticed that they don't vary too very much, <5%, except for #5, which is around 10%.

Don't forget to add the +/- 3^ of a perfectly
calibrated OPHIR head.... or more if not...

Jerry