# Green laser pointer problem, mechanical or optical



## Stormy (Mar 13, 2007)

Some weeks ago I got a green laser pointer 5-8 mW(made in China). It works fine, except for one thing.
When I turn the pointer around its length axis, at a certain angle it starts dimming from 100% to about 10% and when I turn it further it increases back to full output again.
Does anyone know if this is a mechanical problem or a polarisation "feature"?


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## Ashton (Mar 13, 2007)

That's either a bad battery connection or a bad button connection... I suggest either RMAing it or disecting it...


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## SenKat (Mar 13, 2007)

That could also be caused by your crystal assy being loose. If it slides a micron out of position, it can drastically affect the ammy of light !


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## pseudonomen137 (Mar 13, 2007)

Take off your glasses next time . There are other possibilities I guess, but chances are nearly 100% that its due to polarization.


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## Stormy (Mar 15, 2007)

Ashton was right for both causes.
I replaced the normal alkaline cell with NiMH cells and the problem vanished,
apart from some output variations when I push the button a bit harder.

Another interesting thing is that on NiMH cells it seems to be a bit brighter and the unit heats up (well, heat is far too much; warms up) somewhat more and somewhat faster.
I know alkaline cells have a higher internal resistance and are not suited for higher current use (the unit draws about 300mA at 3V and 280mA at 2.4V), but this seems to be not very logical.


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## luvlasers (Mar 15, 2007)

Ashton said:


> That's either a bad battery connection or a bad button connection... I suggest either RMAing it or disecting it...


 
Good call with the batteries.

For a generic 5-8mW, the cost of shipping for RMA would probably be more than the value of the pointer. If you are the seller of these kinds of pointers, giving a warranty is very safe


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## pseudonomen137 (Mar 15, 2007)

Power decreasing and increasing while turning across the length axis? It still sounds like a polarization issue to me, though I guess there could be some very very very unlikely situations where contact problems could come into play. Were you wearing any type of glasses or anything at the time when you saw that?

Honestly, with the NiMH versus alkaline, unless it has something to do with contact and different battery size between the two (once again, possible, but very unlikely), I'd guess you're either using poor alkalines or maybe its just a placebo effect sort of deal. Power will fluctuate on green DPSS and batteries can affect this a little bit, but turning the laser would be completely unrelated and any correlation would either be coincidence, or a 1 in a million that some very odd contact-related problem is occurring. Good luck.


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## Hemlock Mike (Mar 15, 2007)

Stormy brings up a good point. That little damn power switch. Most are made for 50 mA rated 100K cycles. We're pushing them to the max and there will be failures. I've had to replace several buttons because they failed. A 0.50 ohm contact resistance here can drop output a bunch depending on the drive circuit.

Mike


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## Stormy (Mar 16, 2007)

pseudonomen137 said:


> Power decreasing and increasing while turning across the length axis? It still sounds like a polarization issue to me, Were you wearing any type of glasses or anything at the time when you saw that?



Yes I do wear glasses, but even without my glasses the unit behaved the same way.




pseudonomen137 said:


> Honestly, with the NiMH versus alkaline, unless it has something to do with contact and different battery size between the two (once again, possible, but very unlikely), I'd guess you're either using poor alkalines ...


The alkalines are not bad but certainly not the best (Ikea branded Varta), but the NiMH cells are top quality with better contacts and a bit different size (read: fits better).


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