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

[lasersbee]

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.

The readings you indicated seem to be way off....
I've sent you a PM requesting certain Info on your LaserBee I...

We will solve this problem or send you a New LaserBee I...

[EDIT]
I have been in contact with "taggalucci" and because of time zone
differences he will supply us some data we requested after he gets
some ZZzzzzs.


Jerry

[Laser Ben]

So my question still stands, have you actually ever checked a LaserBee meter against a NIST traceable calibrated meter? Your website shows you measuring the same laser with the laserbee and an old Newport meter.

[lasersbee]

The "old" Newport 1825C and brand new 818T thermal head were calibrated
by Newport in California 7 months ago... It took 5 weeks to get the meter anf
head back...

Jerry

[Laser Ben]

Picture of the cal document?

[Doc]

I checked my Laserbee against my calibrated Scientech 365.

From 5mW to about 105mW it was never more than 3-4mW adrift. I couldn't go any higher with the diode I was using.

[Laser Ben]

Calibrated against what?

[Doc]

Calibrated against what?

Ben, I won't be sucked in to any childish games, I'm far far too old for that stuff.

Gauge calibration is not my field, but I believe the procedure used is to apply a given amount of electrical power to the heating element in the thermopile, then using a correction factor for the head; the expected scale reading is set.

AFAIK they aren't checked against another meter.

I did this check as I'd just bought the laserbee as a convenient tool for DPSS temp tuning and I was interested in the comparison.

Taggalucci has already stated that power seems to increase beyond 5v modulation, maybe a. the assumed 5v is not 5v, b, there is some connection problem between the mod signal and the lasers, c. the lasers *are* down on power?

[Diachi]

Ben, I won't be sucked in to any childish games, I'm far far too old for that stuff.

Gauge calibration is not my field, but I believe the procedure used is to apply a given amount of electrical power to the heating element in the thermopile, then using a correction factor for the head; the expected scale reading is set.

AFAIK they aren't checked against another meter.

I did this check as I'd just bought the laserbee as a convenient tool for DPSS temp tuning and I was interested in the comparison.

Taggalucci has already stated that power seems to increase beyond 5v modulation, maybe a. the assumed 5v is not 5v, b, there is some connection problem between the mod signal and the lasers, c. the lasers *are* down on power?

I was thinking A. too.

Taggalucci, where are you sourcing the 5V? It's common to put the Mod inputs in parallel with the driver power inputs if it is the 5V version driver that you have.

[lasersbee]

I'm still waiting for "taggalucci" to contact us with the
info we requested yesterday...


Jerry

[taggalucci]

I was thinking A. too.

Taggalucci, where are you sourcing the 5V? It's common to put the Mod inputs in parallel with the driver power inputs if it is the 5V version driver that you have.

I have a 5v SMPS (S-60-5 I believe) which supplies the red and green drivers. This is voltage adjustable, +/- a few %, and I have tested this with a voltmeter to confirm the 5v supply.

For this exercise, I have a lab PSU set to 5v 300mA providing the signal voltage (I believe I have tested this too) and this is connected via the ILDA connector to the RGB signal pins in parallel (I wired a separate DB-25 connector this way for bench testing purposes).


If anyone knows of any other factors which should be considered regarding drive or signal voltage/current, please raise them for discussion?

I'm still waiting for "taggalucci" to contact us with the
info we requested yesterday...

Sorry for the delay. The timezone difference can be a bit of a pain. I'm currently on client's site, so won't be able to provide these details until this evening. Thanks again Jerry for your responsiveness.


Laser Ben,

Your knowledge and contributions are welcomed. I initially started this thread to discuss procedure and not apparatus. Obviously I understand that absolute results will be dependent on apparatus. If you feel a need to bash LaserBee, CNI, my voltmeter, my SMPS or anything else please feel free to start another thread for this I would like to keep this thread constructive and allow the facts to speak for themselves. It will make better reading for others in future who may wish to use the knowledge shared here for their learning. Thanks for your understanding