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How powerful are 5 mW eBay pointers in reality?

Thinkcat

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Hello

After getting six "5 mW" pen pointers, two 405 nm (violet), two 635 nm (orange), one 532 nm (orange) and one 650 nm (red) I wonder if these really are all 5 mW pointers.

The red one is misaligned, and in addition to the dot, there is a semi-arc around it. The two orange ones were equally bright and good for presentations. One of the violet pointers has an awful lot of divergence, the other one is fine.

What concerns me most is the green pointer. There is a glitch in its power button. It is as if there were two power levels coming up randomly, and rubbing your finger back and forth while pushing the button will get you the higher power unless you already have it.

I have two questions. First one is, has anyone done measurements with these cheap 13-in-a-dozen pen pointers? What have been the results?

And the second one. Is it possible to determine the emitted power of the green pointer with any accuracy, maybe to 10 or 20 percent, by measuring the current it draws from the batteries?
 
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ChaosLord

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Yes, cheap chinese pointers have been measured from ebay and other places. There are a few rather recent threads on these. The 532nm almost always are > 5mW.

As far as measuring output based an current draw, you can get an estimate, but actual output will vary. Diode efficiency, crystal quality/alignment/efficiency, lens quality, ect. All effect final output power.
 

Thinkcat

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Tested my green pointer. It draws about 390 mA. How does this sound?

One of my violet pointers draws 150 mA. The one with too much dispersion. The other is 210 mA.

Orange one 45 mA. Red one 90 mA.
 
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Antharak

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I've metered ebay pens on my LPM from 1mw to 170mw. You really can't tell what the output is without a LPM. Any other method is just not accurate.
Ed
 

Thinkcat

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If you want a real 5mW pen look here.

Laserglow Technologies
You really can't tell what the output is without a LPM. Any other method is just not accurate.
Ed
I assume my best bet would be an LPM and a good handful of random pen lasers. Then I would have much choice with brightness and power and beams and I wouldn't have to spend more than 50 dollars (price plus postage) to get a single good pointer.

Question is, how to get a good enough LPM without spending a fortune? I am not yet so much into this that I would want to invest more than what is absolutely necessary. What about Bauer's HLPM II?
 
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Usually they are overspec. 635nm pen?!:drool: Nice, that shouldn't be too overspec.
 
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Benm

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Hello
What concerns me most is the green pointer. There is a glitch in its power button. It is as if there were two power levels coming up randomly, and rubbing your finger back and forth while pushing the button will get you the higher power unless you already have it.
If the vendor intended these lasers to be actually 5 mW (which could be the case, or also just a matter of complying with ebay or customs rules), the direct-diode ones are mosty likely to be sort of accurate.

The green is a different story. Due to the way these work their output depends on factors like ambient temperature, and could be far under or over what is specifed. If it draws 390 mA of current it probably is well over specification, or very inefficient. Such current draw is typical of 532 laser modules with output powers in the range of 50 to 100 mW.
 

Benm

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It could be that much indeed - depends on how (in)efficient they are, and for low price units you cannot expect them to have an IR filter installed, although you can do that quite easily yourself if there is some room inside the unit. You could just glue it to the output aperture (preferable on the inside of the unit) if you must.

Note that the IR is -not- collimated with the green light usually. What leaks out is 808 nm pump light which usually has a much larger divergence than the green, meaning it is mostly hazardoes at close range, but at several meters range its contribution is likely to be marginal.
 

Rifter

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Just tested my 2 ebay pens on my RE X4, both ebay lasers are 2xaaa units. both labeled less than 5mw power.

Red one tested 32mw peak avg around 28.

green one died during testing, made it just over 60 seconds and died, was still climbing and was at 62mw when it dies.
 
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Bionic-Badger

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Whereas a 5mW red will last forever, even the 5mW green pens eat through batteries and warm up pretty quick.
 

Rifter

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Pens have nearly no heat sinking. The green DPSS lasers use IR to create the 532 wavelength. Its an extremely inefficient process. I dont know the math but the IR is in the >300mW range. Maybe more. Those pens cannot handle one minute of constant >300mW power. Thats why it died. I would not push any pen over 30 seconds unless it was true 5mW.
I was giving them the benifit of the doubt about its power rating till i tested it :) My laserglow 5mw green pen has a duty cycle of 90 seconds i assumed this ebay pen would be the same if it indeed was 5mw, but as we now know it was far from 5mw.
 




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