Suggestions welcome on how to verify the power of DPSS and diode lasers

[taggalucci]

I recently purchased a Laserbee I LPM and took my first measurements with it last night. For each of the lasers 635nm (direct diode), 532nm (DPSS) and 473nm (DPSS), the most immediate thing I noticed is that the levels measured were quite a bit lower than I was expecting. And in the case of the green and red, lower than CNI's test reports accompanying the lasers.

I have read elsewhere that one needs to allow time for the lasers to warm. But how long is long enough?

Also, I'm assuming that these measurements should be taken with an analogue drive signal of 5v (no more, no less). I have noticed when I accidentally, and very briefly, over supplied the analogue signal, the power output was visibly higher. Could it be that the drive signals need to be higher than 5v?

Clearly if the CNI lasers prove to be much lower than specified, I am keen to resolve this with them. So I need to ensure I am not mistaken.

Thanks in advance.

[drlava]

typically 10 minutes is long enough for a dpss warm up. Also note in the manual if they are supposed to be attached to a heatsink/optical plate during operation.

What were the ratings and what did you measure? Were they all low by approximately the same percentage? If so my instinct is to question the meter.

[Laser Ben]

I recently purchased a Laserbee I LPM and took my first measurements with it last night. For each of the lasers 635nm (direct diode), 532nm (DPSS) and 473nm (DPSS), the most immediate thing I noticed is that the levels measured were quite a bit lower than I was expecting. And in the case of the green and red, lower than CNI's test reports accompanying the lasers.

First off, I would get/borrow a meter that gives you real power measurements in actual units, not in special laserbee power units.... Then if you have problems, there is something wrong with the lasers. I personally do not trust the accuracy of the DIY/"hobby" meters because as far as I know (and please prove me wrong *Jerry*), none of them are (or ever have been) calibrated off an actual calibrated power meter...

[polishedball]

First off, I would get/borrow a meter that gives you power measurements in actual units, not in special laserbee power.... Then if you have problems, there is something wrong with the lasers. I personally do not trust the accuracy of the DIY/"hobby" meters because as far as I know (and please prove me wrong), none of them are calibrated off an actual calibrated power meter...

While I am not saying it is linear or anywhere near a real pro meter, this link shows calibration to a real power meter (newport) ? http://www.bauer-electron.com/eby/eby1wlpm.htm Somewhere in the docs I thought it was stated he calibrated to the meter for all units he sold.

For me I just need ballpark and the cheapo DIY's serve me fine.

[mixedgas]

Popcorn popped and waiting.

Steve

[taggalucci]

OK...

Lasers were mounted to an optical plate.


I allowed these to warm for 10 minutes or so, though I returned to test over the course of 30 mins or so. Definitely observed a rise, though not by large amounts.

Red 635nm

Rated > 900mW
CNI measured 976 mW
Observed ~ 585 mW

Green 432nm

Rated > 450mW
CNI measured 544mW
Observed ~ 218mW

So as you may have seen from the desription of the Laserbee, it is calibrated and reads in increments of 1mW. Although I'm not expecting the performance of a $1000+ LPM, I'm not expecting it to be out by 100s of mWs.

Clearly I'll need to verify these readings with another meter before making any claims. Just thought I'd check my process with you before I hassled someone like Dave to help me out with a reading of the lasers.

[Laser Ben]

While I am not saying it is linear or anywhere near a real pro meter, this link shows calibration to a real power meter (newport) ? http://www.bauer-electron.com/eby/eby1wlpm.htm Somewhere in the docs I thought it was stated he calibrated to the meter for all units he sold.

For me I just need ballpark and the cheapo DIY's serve me fine.

Show me a calibration tag, some proof that it is NIST traceable, or any proof that the number it shows is based in any reality... I have a very similar meter here which is over 20% off from my calibrated LabMax unit...

[taggalucci]

Show me a calibration tag, some proof that it is NIST traceable, or any proof that the number it shows is based in any reality... I have a very similar meter here which is over 20% off from my calibrated LabMax unit...

I wouldn't expect calibration tags, NIST traceability etc. on a hobbyist LPM, I would just expect it to be within 5-10mW of a more expensive unit like your LabMax unit.

When you say "very similar", does it have a name (for the record)?

I actually got the Laserbee to measure differences between various optics and optimising optics alignments, so relative readings vs absolute readings was the point.

However... obviously the meter is sold to provide absolute readings (in mW) of the kinds of lasers I'm using along with many others on this forum, and I would expect ballpark measurements, just as mentioned by polishedball.

I will try to have my measurements verified to identify the actual discrepancy. In the meantime, we can assume it is the LPM (or maybe not)

[Laser Ben]

I don't expect the meter you receive to be traceable, however the meter is is based off of should be calibrated. The meter I was referring to is an older LabMaster unit.

Jerry, do you even own a Calibrated meter? If so, please tell (for the record, so people know what their measurements are based on), if not, what are you basing your measurements on?

[lasersbee]

First off, I would get/borrow a meter that gives you real power measurements in actual units, not in special laserbee power units.... Then if you have problems, there is something wrong with the lasers. I personally do not trust the accuracy of the DIY/"hobby" meters because as far as I know (and please prove me wrong *Jerry*), none of them are (or ever have been) calibrated off an actual calibrated power meter...

Hey mixedgas... got your popcorn ready...
I just love dealing with 18 year old know it alls that pull info out of their butt..

Hey L_B......
what the he!! are special laserbee power units...
Is there something that you know that we the designers of the LaserBee products
don't know about our power units....

Please... don't be shy... do tell.... or are you just Trolling..
I have more important things to do than play your idiotic games...

Things like solving this LaserBee I user's problem....

[EDIT]...
All your meter questions are answered on our LaserBee products page on our
website... (Our website is not hidden... it's in my Sig)


Jerry