Laser diode measurement question

[m-thew]

I'm trying to see just what the out put of my laser is. I have tried comparing the output of a known source(solar panel) before and after being hit with the beam and also measured the volts and mA at the 3 wires going into the module from the circuit board. The solar panel results were inconclusive as the wavelength is probably not registering. I am reading 3.0 volts and 39 mA (using a 6v power source) at the junction of the board and the brass head.
Can this be? Am I testing the right things?
Using Ohm's Law that is 12mW from a laser pointer?
I have searched CPF and the LED museum for the correct procedure and I guess I missed it .
Matt

 

[Wylie]

Hi m-thew,
I do not think I will be of much help but I am curious as to if you got your laser from www.thelaserguy.com. He has some of the best 3 volt 645 to 650nm modules I have found. If this is one of his three volts they have a current limiting curcuit board so what you have posted would be about right except for the output. This is just a guess as I do not know much about lasers I just use them to build fishing rods. Yes fishing rods.
These are the specs for his modules anyway,
Specifications:
Operating Current: 60 mA I will test this as soon as I get my new multimeter.
Operating Voltage: 2.6 VDC to 3.2 VDC
Spot size: At 5 meters is 6mm diameter
Operating Temperature: -10 C to 40 C
Range: 2600 Feet
Diode: 645 nm, 5 mw industrial grade rated at 12,000 to 15,000 hours constant on operation.

keeping it real, bright

,
Wylie

 

[m-thew]

Hi Wylie,
I got this one out of a laser level that wasn't too level. The laser guy's offerings do seem priced very fairly though.
This one has a type of trim pot on it that regulates output and I'll bet you are right regarding the current limiting part of my laser.
How will you check yours when you get your new multimeter? The specs sound about the same as mine.
Fishing rods eh? I see your signature now, I'm off to wylierods.
Thanks for your help.
Matt

 

[MrAl]

Hello there,

Seems to me, you would have to know these things:

1. Efficiency of the solar panel at that wavelength
2. Optimum resistor load for the solar panel
3. Distance from the source

You could easily measure distance,
and you can get the optimum resistor
load value by using a pot and adjusting
for max power output from the panel,
but you would have to know the eff of the
panel or be able to calibrate it somehow.

Another way would be to compare it to
a known source, and use the inverse square
law and the ratio of the beam areas to
compute the output.

Let us know what happens ok?

Take care,
Al

 

[Wylie]

Hi m-thew,
You may have a laser from Deharpports but they run at 80 milliamps I think. There are only really a few manufactures of laser modules as far as I know but they do different things with them. Deharpports are about 12 millimeters in diameter but I do not know who builds them for them.
As for the testing I will just check the leads to the diode after I hook up a six volt source. I have a little Radio Shack 4XAA pack with a switch and wires that I will hook up to the lasers I have.
As you have mentioned your laser came from a level so it may be a little larger than the 8.2 mm diodes the laser guy sells. I still have one of Deharrports around here somewhere and I can check it too when I get the tester. The terminology (pot) is something new to me. I will have to look around and see what this is.
This where Deharpports website is at http://shop.store.yahoo.com/deharpport/redmodule650nm.html and here is a link to Lasermates website as well. Lasermate does a bunch of different laser modules. http://www.lasermate.com/GRImodule.htm
I'll let you know what I come up with when I get the tester.
I thought you might find lasers and fishing rods to be an odd couple but they work very well together.

Wylie