Is a 5mw laser hack really possible?

LEDrock · May 28, 2011

I've looked up on google about how to up the power of a 5mw laser pointer and am starting to wonder if it's real or not. I mean, why would anyone BUY an expensive high powered one if they could just increase the power of a cheaper one? I have a 5mw, but don't want to ruin it, so I figured I'd ask first.

Here's a link to instructions of what I'm referring to: http://www.ehow.com/how_5698277_modify-5mw-green-laser-pointer.html

Illum · May 28, 2011

Diodes are weak in performance when it comes to poor heat dissipation. Take a 5mm LED for example, continuous current maxes out at 20ma, primarily because the epoxy dome is terrible at convecting heat. However, if the current was pulsed, the die can sustain currents upwards of 100ma without incurring substantial damage. Same goes for laser diodes. If the diode within the copper slug is sufficiently cooled and coupled with a CC driver capable of PWM it is possible to mod a 5mw to outputting maybe twice its intended output. With 532nm the crystal configuration is more complicated than the 670nm described above. Increasing the output of a 532nm diode would have to take into consideration the overhead of not only the 808nm diode but also the Nd:YVO4/KTP crystal. Pot modding is often the #1 mentioned method, pot modding is simply changing the foward current to the diode. It may incur a minor increase in output, but most I've seen really do not justify the effort for the modification with regard to the decrease in duty cycle as well as diode life. To build a dedicated PWM/CC to push a 5mw rated diode is like putting a ferrari engine in a minicooper. It is not only cost prohbitive, but it can be only completed with great difficulty, if at all.

LEDrock · May 28, 2011

Illum said:
Diodes are weak in performance when it comes to poor heat dissipation. Take a 5mm LED for example, continuous current maxes out at 20ma, primarily because the epoxy dome is terrible at convecting heat. However, if the current was pulsed, the die can sustain currents upwards of 100ma without incurring substantial damage. Same goes for laser diodes. If the diode within the copper slug is sufficiently cooled and coupled with a CC driver capable of PWM it is possible to mod a 5mw to outputting maybe twice its intended output. With 532nm the crystal configuration is more complicated than the 670nm described above. Increasing the output of a 532nm diode would have to take into consideration the overhead of not only the 808nm diode but also the Nd:YVO4/KTP crystal. Pot modding is often the #1 mentioned method, pot modding is simply changing the foward current to the diode. It may incur a minor increase in output, but most I've seen really do not justify the effort for the modification with regard to the decrease in duty cycle as well as diode life. To build a dedicated PWM/CC to push a 5mw rated diode is like putting a ferrari engine in a minicooper. It is not only cost prohbitive, but it can be only completed with great difficulty, if at all.

As far as difficulty, the instructions in the link made it look really simple. I just wasn't sure if it's been tried by anyone here. I was just wondering if they had and what their results were.

But if something like this could be done, I'd be satisfied if running it only a few seconds at a time.

LEDrock · May 31, 2011

LEDrock said:
As far as difficulty, the instructions in the link made it look really simple. I just wasn't sure if it's been tried by anyone here. I was just wondering if they had and what their results were.

But if something like this could be done, I'd be satisfied if running it only a few seconds at a time.

Well, here's an update. I went ahead and took my laser pointer apart, breaking it in the process. It also turns out that the insides aren't exactly as shown in the instructions. That little screw that needs to be tightened couldn't be tightened at all. It just spins like a wheel! I had that pointer for 13 years. I was just hoping to make it a more powerful one, but instead managed to turn it into junk.

bshanahan14rulz · May 31, 2011

Luckily, pointers are cheaper now than 13 years ago

Benson · Jun 1, 2011

It's not a screw, it's a potentiometer. And many trimpots do not have stops to limit rotation, so they will spin freely. If you're lucky, it may not be dead, might just be reduced to nothing.

Try turning it slowly while applying power, if it increases gradually, you're going the right way, set it to the brightness you like (and don't go too high). If it comes on instantly, you just wrapped around from 0 to max, and will quickly burn it out -- go the other way.

LEDrock · Jun 2, 2011

Benson said:
It's not a screw, it's a potentiometer. And many trimpots do not have stops to limit rotation, so they will spin freely. If you're lucky, it may not be dead, might just be reduced to nothing.

Try turning it slowly while applying power, if it increases gradually, you're going the right way, set it to the brightness you like (and don't go too high). If it comes on instantly, you just wrapped around from 0 to max, and will quickly burn it out -- go the other way.

Actually, the thing broke when I took it apart. The contacts from the control board to the laser head broke off completely so there is no way to supply power to the head now. It's all in the garbage which has been taken out. No big deal I guess. Just disappointing that I didn't get the "easy high power laser from my low power laser" that the link seemed to promise.

bshanahan14rulz · Jun 3, 2011

I think in the olden days the nonlinear optics varied greatly in efficiency and the best way to get around lots of production duds was to use larger NLOs. Depending on if you got a good setup or not (luck of the draw), you could increase the pump's output power and the NLOs will follow. On a bad setup, the pump would already be outputting a lot, and the inefficient NLOs would lase JUST enough to make a sellable pointer.

Nowdays, the crystals don't vary so much, and manufacturers can use smaller crystals and still get a low number of "duds".

Slickseth · Jun 3, 2011

To answer your question: Yes, it is possible. But the lifetime of the laser will be greatly reduced. The output will not be stable, and the beam will likely shift modes and vary as the crystal heats up. I have done this mod many times, and the results were never reliable.

andyw513 · Jun 6, 2011

I agree with the others in saying that while it can be possible, the pot-modding of a diode can cut the lifespan of it drastically. If it's a cheap laser and you want the experience then I say go for it, but if it's one that is a higher end (or higher cost) model then I would personally keep it unmodified.

Is a 5mw laser hack really possible?

LEDrock

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Illum

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LEDrock

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LEDrock

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bshanahan14rulz

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Benson

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LEDrock

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bshanahan14rulz

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Slickseth

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andyw513

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