Measure mW

[Pestario]

I have ordered my first laser now, and I just can't wait :0) There's only one thing i was wondering about. Do you know where I can buy a cheap "laser output power measurement tool"? Not sure what to call it, so it ended ut with kind of a long name I want to get an instrument that I can use to measure the output mW, and I don't want to put too much money into it...

 

[diachi]

Laser power meter, you can get one but they cost over $200

 

[Pestario]

Ok, that was a little more than I had counted... No other way to find out the mW?

 

[diachi]

nope, well you could send your laser to one of the trusted members of the forum that has a Laser Power Meter and get them to test it for you.

Diachi

 

[Cyparagon]

One can infer an approximation with reference to the current.

 

[diachi]

really depends on the driver and diode

 

[daguin]

One can infer an approximation with reference to the current.

If dealing with a unit built by a trusted individual, I would agree. Unfortunately, with many commercially available lasers, this "approximation" can vary widely. This is especially true with DPSS lasers. The efficiency and alignment of the crystals significantly effect power output. Add to that the often amazingly inflated claims for the power of a laser and you are still left with getting it tested by someone with a quality meter to have a reliable idea of the output.

Peace,
dave

 

[pseudonomen137]

One can infer an approximation with reference to the current.

If you are working with a collimated diode laser (IE red, blu-ray) and you have the spec sheet for the exact diode used, as well as data from other of the same diode with power vs. current graphs, you can get a rough estimate yes. Even with the same diode though, the ones I've gotten for Coherent have power vs. current graphs unique to each and every diode, as even diodes of the same model - and from the same batch, will show similar characteristics.

If you're dealing with a DPSS laser though (IE, green or blue) there's not a chance. Even if you know the current going directly to the diode, I doubt you could estimate output to more than a +/- 500% margin of error.

Unfortunately there is just no such thing as a cheap power meter. Even for a low end reputable brand, you end up paying $400+. You can find things more appropriately called laser power estimators down to the $150-300 range, but anything less than that and you're just out of luck. As said above, either asking a local university if they could test it for you, or paying two way shipping for someone on the forums with a meter to test it for you (I can do this if you cover all shipping costs) is the best option.

 

[diachi]

You could get this for under $210

Review by Murudai

 

[Pestario]

Thx for the advices. Still too much money for me, and I doesn't think I get the correct result with Ohm's law... It's a DX laser, and that's why it would have been fun measuring it.

 

[diachi]

Ohms law has nothing to do with it , aslong as you have a multi meter that can read Voltage and Current.

What DX laser is it anyway?

Diachi

 

[Pestario]

Just thought that if I used the current and volt, I could use Ohms law to figure out the mW... I bought the True 50mW greenie. Just ordered the 200mW Dilda too :0) Glad I waited until the price dropped :0D

 

[pseudonomen137]

Just thought that if I used the current and volt, I could use Ohms law to figure out the mW... I bought the True 50mW greenie. Just ordered the 200mW Dilda too :0) Glad I waited until the price dropped :0D

Nah, sorry man: its expensive laser power meter or bust

 

[Pestario]

Hmm... Just have to try and find someone who has measured theirs, check what kind of things they have melted or burned, and check if my lasers kan do any of that... Then i could get a clue of the mW. Hehe.

 

[daguin]

Hmm... Just have to try and find someone who has measured theirs, check what kind of things they have melted or burned, and check if my lasers kan do any of that... Then i could get a clue of the mW. Hehe.

Why did you ask if you weren't going to believe the answer?

Peace,
dave

 

[Pestario]

[quote author=Pestario link=1215003844/12#13 date=1215064795]Hmm... Just have to try and find someone who has measured theirs, check what kind of things they have melted or burned, and check if my lasers kan do any of that... Then i could get a clue of the mW. Hehe.

Why did you ask if you weren't going to believe the answer?

Peace,
dave[/quote]


Maybe I haven't been paying attention, but which question do you mean?