Inacccuracy of LaserBee products

I am making this thread because the accuracy of all LaserBee products I have encountered have been problematic, and posting in this thread http://laserpointerforums.com/f42/regarding-recent-questions-lpm-accuracy-70181-2.html#post1154526 got no attention to the problems at hand with the laserbee products.

LBII

The set up with my stable 808nm laser. (The same wavelength used to calibrate the laserbee's IIRC)

The Ophir reading (Minus 7 mV for zeroing)


The laserbee II reading:


I know that my Ophir is reading correct because I sent it off to MarioMaster who checked it against his Coherent Fieldmax, it was reading almost the same as the fieldmax.

The laser bee II (in my case) is around 10% off in the 1.8W range, at higher powers the inaccuracy increases.
There has been no damage to the Laser Bee since I bought it.


HLPM
I also received a used HLPM recently.
This test was done with a pen laser as I don't have a lab style 405nm laser.
Ophir reading: 45mV (minus 7 for zeroing) so 38mW.
The Laserbee II read 35mW.
The HLPM read 4.4mV, and according to the correction factor chart it should be multiplied by 23.3. 102.52mW That's 70% off!
When reading in the red spectrum it's fine, but I think the wavelength chart may be a little off.

Could any other users with an HLPM, a 405nm and another power meter confirm the results?

Conclusion
I believe that the laserbee power meters are calibrated individually, but not curve adjusted individually which could lead to inaccuracy in some units when not metering in the 400-600mW range that the power meters are calibrated in, from my own testing with TEC based LPM's the curve adjustment is NOT the same from TEC to TEC, and if the laserbee's are not being individually curve adjusted some units will enviably be inaccurate at the higher range of powers. If this is the case then I'm sure a fair number of the LB LPM's here are not reading as they should at the higher ranges.

The HLPM's wavelength chart is most likely off, meaning that readings not in the 600-700nm spectrum will be off, I would like someone else to confirm this as my unit could be defective.

Follow up


I received a LaserBee-A from someone who wanted me to add my v3 datalogging board to it.

With the exact same laser, untouched since the initial tests I got a reading within 2mW of the initial test on my Ophir.
This was what I got on the LaserBee-A.


LB-A 1.810W
Ophir 1.844W
LB-II 1.656W

Unlike LaserBee has suggested it now appears that the LB-II was reading incorrectly, and my Ophir head is reading correctly. That or both my Ophir, and the LB-A are reading incorrectly, which I highly doubt.
I would still like to know if the LB-II's are curve adjusted individually as I believe that's what was the result of the LB-II inaccuracy.

Re: Accuracy of LaserBee products

I'll be sending you my LPM sometime next week. While my Ophir has seen a lot of use, and hasn't been calibrated in a long time, it does read in line with three other Ophir heads I have handled, and it is inline with readings from Lazeerer, and his two LPMs.

Re: Accuracy of LaserBee products

I'm glad I caught this thread, I think my Laserbee II needs some calibrating also. I recently visited dmacrae & metered some of my handhelds his ophir sensor LPM. The readings came out ~300mw higher on his LPM than they have on mine and this wasn't an issue of seeing an immediate reading on the ophir compared to the numbers climbing up there on the Laserbee. Same batteries, same lenses but different readings. I'll be getting in touch with Jerry soon to get my LPM back on track because I friggin love my Laserbee II

:beer:

Re: Accuracy of LaserBee products

danefex said:

I'm glad I caught this thread, I think my Laserbee II needs some calibrating also. I recently visited dmacrae & metered some of my handhelds his ophir sensor LPM. The readings came out ~300mw higher on his LPM than they have on mine and this wasn't an issue of seeing an immediate reading on the ophir compared to the numbers climbing up there on the Laserbee. Same batteries, same lenses but different readings. I'll be getting in touch with Jerry soon to get my LPM back on track because I friggin love my Laserbee II

:beer:

Click to expand...

Thanks for the post! Make sure you get Jerry to curve adjust it, as that's probably what it needs rather than a re-calibration.

I hope this problem isn't widespread with LB users. Others that have owned both an Ophir and LB have had them read the same, but small variations in the TEC's could be throwing off the curve adjustments, and it could affect a large portion of the LB LPM's. As Trevor said

Trevor said:

If they are not accurate, it could mean that a lot of our benchmarks and fundamental assumptions regarding laser diodes (output in millwatts being less than input in milliamps, efficiency, etc) are incorrect.

Click to expand...

:undecided:

Is it possible that this happens after some 't' amount of time since the units were manufactured and calibrated? Perhaps it is some kind of aging affect where the thermal coat on the sensor is slowly chemically altered over time. A kind of 'rusting' effect due to being in open air for some time 't'? A chemical change could easily alter its absorption and thermal properties. This would be difficult to test however...

Just speculation of course..

The laserbees are well calibrated at the manufacturing stage.. so I assume that means they are checked against multiple data points across multiple wavelengths. To me, this means that none of them can be < 10% accurate for all power scales and wavelengths. That's a lot to ask from a TEC based device.

Even a thermopile needs a curve adjustment, right?

It could be an aging effect, IIRC my meter was about 7 months old at the time of the above measurements, how old is yours danefex?
DTR's is fine though, and reads the same against his Ophir, so I think the chance of it being an aging issue is slim.

As I understand it calibration for these units involved a single 808nm laser in the range of 400-600mW and the curve adjustment is assumed to be the same from TEC to TEC, I don't think each unit is individually tested against multiple data point or wavelengths.

From my own results without proper curve adjustment a TEC based LPM can be off by as much as 25% when reading power not near the point at which it was calibrated.

As for the HLPM's I don't know how those are calibrated or how the wavelength chart was determined, but it's hardly accurate

Meatball said:

Is it possible that this happens after some 't' amount of time since the units were manufactured and calibrated? Perhaps it is some kind of aging affect where the thermal coat on the sensor is slowly chemically altered over time. A kind of 'rusting' effect due to being in open air for some time 't'? A chemical change could easily alter its absorption and thermal properties. This would be difficult to test however...

Just speculation of course..

The laserbees are well calibrated at the manufacturing stage.. so I assume that means they are checked against multiple data points across multiple wavelengths. To me, this means that none of them can be < 10% accurate for all power scales and wavelengths. That's a lot to ask from a TEC based device.

Even a thermopile needs a curve adjustment, right?

Click to expand...

Jerry's never said that occasional recalibration is necessary for LaserBees. Though I suppose that doesn't mean it's not necessary.

What's interesting about the LaserBees is that the curve adjustment is statically defined in code, whereas the calibration constant changes between meters. I've inferred this from finding only the calibration constant present in the EEPROM - meaning that unless the microcontroller code is changed for every meter (highly unlikely), the curve adjustment cannot possibly be defined differently per meter.

Jerry's said in the past that no two TEC's are alike - so the static curve adjustment could play into this a little bit.

The sensor coating could also not be spectrally flat... he's said it is, but he's lied about the attributes of LaserBee products before, so it might not be. Definitely should be tested by a third party.

I'm interested to see an official response to this.

Trevor

Trevor said:

Jerry's never said that occasional recalibration is necessary for LaserBees. Though I suppose that doesn't mean it's not necessary.

What's interesting about the LaserBees is that the curve adjustment is statically defined in code, whereas the calibration constant changes between meters. I've inferred this from finding only the calibration constant present in the EEPROM - meaning that unless the microcontroller code is changed for every meter (highly unlikely), the curve adjustment cannot possibly be defined differently per meter.

Jerry's said in the past that no two TEC's are alike - so the static curve adjustment could play into this a little bit.

The sensor coating could also not be spectrally flat... he's said it is, but he's lied about the attributes of LaserBee products before, so it might not be. Definitely should be tested by a third party.

I'm interested to see an official response to this.

Trevor

Click to expand...

I would also like to see an official response, but he hasn't responded to the Peregrine thread yet so I doubt we'll see a response from him here until he's done responding to all comments there.

ARGLaser said:

I am making this thread because the accuracy of all LaserBee products I have encountered have been problematic, and posting in this thread http://laserpointerforums.com/f42/regarding-recent-questions-lpm-accuracy-70181-2.html#post1154526 got no attention to the problems at hand with the laserbee products.

LBII

The set up with my stable 808nm laser. (The same wavelength used to calibrate the laserbee's IIRC)

The Ophir reading (Minus 7 mV for zeroing)

The laserbee II reading:

I know that my Ophir is reading correct because I sent it off to MarioMaster who checked it against his Coherent Fieldmax, it was reading the same as a fieldmax.

The laser bee II (in my case) is around 10% off in the 1.8W range, at higher powers the inaccuracy increases.
There has been no damage to the Laser Bee since I bought it.


HLPM
I also received a used HLPM recently.
This test was done with a pen laser as I don't have a lab style 405nm laser.
Ophir reading: 45mV (minus 7 for zeroing) so 38mW.
The Laserbee II read 35mW.
The HLPM read 4.4mV, and according to the correction factor chart it should be multiplied by 23.3. 102.52mW That's 70% off!
When reading in the red spectrum it's fine, but I think the wavelength chart may be a little off.

Could any other users with an HLPM, a 405nm and another power meter confirm the results?

Conclusion
I believe that the laserbee power meters are calibrated individually, but not curve adjusted individually which could lead to inaccuracy in some units when not metering in the 400-600mW range that the power meters are calibrated in, from my own testing with TEC based LPM's the curve adjustment is NOT the same from TEC to TEC, and if the laserbee's are not being individually curve adjusted some units will enviably be inaccurate at the higher range of powers. If this is the case then I'm sure a fair number of the LB LPM's here are not reading as they should at the higher ranges.

The HLPM's wavelength chart is most likely off, meaning that readings not in the 600-700nm spectrum will be off, I would like someone else to confirm this as my unit could be defective.

Click to expand...

Actually to be fair, my Ophir sensor after 5 seconds, is less than 3% off Jerry's Laserbee deluxe. ~1.5% to be precise. :beer:
I've tested it multiple times. Side by side the meter stands up nicely against the Ophir in everything except speed.
That's pretty darned good. The pk value is 10% off, it can't be helped .
The Laserbee is a solid product.

Seoul_lasers said:

Actually to be fair, my Ophir sensor after 5 seconds, is less than 3% off Jerry's Laserbee deluxe. ~1.5% to be precise. :beer:
I've tested it multiple times. Side by side the meter stands up nicely against the Ophir in everything except speed.
That's pretty darned good. The pk value is 10% off, it can't be helped .
The Laserbee is a solid product.

Click to expand...

I'm not saying all laserbee's are off Seoul, no two TEC's are the same so the curve adjustments will not be the same unit to unit, there will be some good units and some bad units. DTR also has a good LBII unit that reads the same as his Ophir, as I said above this wont affect all units, only some units.

If I am correct then the laserbee is not a solid product since units such as mine, and danefex's have different curve adjustments which are not accounted for and they will end up being off by up to 15%.

Also, this thread isn't just about the TEC based LB's, the optical LB's appear to be off by as much as 70% as well

ARGLaser said:

....... how old is yours danefex?

Click to expand...

Mine is almost 2 yrs old, definitely in need of some tuning up I'm sure

:beer:

danefex said:

Mine is almost 2 yrs old, definitely in need of some tuning up I'm sure

:beer:

Click to expand...

Thanks! Maybe there is something to do with the age; or it could be a contributing factor. Seoul, how old is your unit?

Yeah I'm not sure, I guess we'll see though since you folks are taking the time to find out whats up. Many thanks for doing this! I too look forward to an official response :beer:

Trevor said:

Jerry's never said that occasional recalibration is necessary for LaserBees.

Click to expand...

Whether he's said it or not, from a metrological standpoint: ALL devices used for measurement should be calibrated periodically.

Meatball said:

Perhaps it is some kind of aging affect where the thermal coat on the sensor is slowly chemically altered over time. A kind of 'rusting' effect due to being in open air for some time 't'?

Click to expand...

It's just paint. Most paints are designed to be in air. Being irradiated by laser though? that's a niche market :shhh:

Cyparagon said:

It's just paint. Most paints are designed to be in air. Being irradiated by laser though? that's a niche market :shhh:

Click to expand...

Ah, but that's not necessarily the idea. My assumption is that it is some sort of high temperature paint, designed for use on grills and automotive parts such as mufflers.

Those paints could be designed to 'breakdown' under high temperature, permitting the high temp protection to a component. Or perhaps some gases can be "baked" out of the paint with the application of heat.



Who knows? Again, its difficult to test.

I always thought we should find a thin layer of velvet to use on the sensors, rather than paint.

Meatball said:

Ah, but that's not necessarily the idea. My assumption is that it is some sort of high temperature paint, designed for use on grills and automotive parts such as mufflers.

Those paints could be designed to 'breakdown' under high temperature, permitting the high temp protection to a component. Or perhaps some gases can be "baked" out of the paint with the application of heat.

Who knows? Again, its difficult to test.

I always thought we should find a thin layer of velvet to use on the sensors, rather than paint.

Click to expand...

I believe that Jerry uses some sort of automotive paint (perhaps for break callipers) that comes out as a powder and is baked on in an oven, or partially baked in this case.

The ideal thing to use for the sensors would be thin black ceramic plates, but those are difficult to source.
As for velvet, are you talking about the fabric?