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520 pen build help

djQUAN

djQUAN

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cantthinkofone said:
How would I get it to 5mw though? It would be sweet if a weakening lense was out there. Don't acrylic lenses take 20-30% away. At 17mw it would limit it to like 11.1 or something like that.
Click to expand...

see my post above:

djQUAN said:
I made a single mode 450nm pen running at 100+mW. Using a cardboard with a pinhole about 0.5mm diameter ('drilled' with a 1.4W in focus) inserted in the cap restricts the output power to 5mW (LPM'ed) to be safely used at presentations. Remove the restrictor for full beam visibility when used outdoors.
Click to expand...
 





cantthinkofone

cantthinkofone

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I am more safe now. I have eye ware and everything. I'm not a total noob. My jack ass friend shined one directly in my eye on purpose. He's not even my friend anymore so it's all good.
 
Leodahsan

Leodahsan

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Way 1: Electronics (my preferred)
Some kind of "low" mode and "high" mode? A proper PWM designed circuit, would give you the proper results. Blinking at a fast enough rate it won't be noticeable (well, kinda of)

OR

Maybe a build with a small switch (small like a dip) so you can change the current on-the-fly?

Way 2: Optics
The weakening lense you said is called a Neutral Density filter. I'd be worried about the damage threshold though.
neutral density - Free Shipping - DX

Ghetto style
DICHROS from dvd/cd burners can reflect some % of the power. Using a red dichro may reflect partially your 520nm beam, giving you lower power.

Way 3: Pinhole
See post #10
 
NKO29

NKO29

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I have a smart board infront of me half the day at school. because it's a matte finish it doesnt reflect at all really. Fact is that 50mW will 99.99% not hurt anybody or cause discomfort. I have used a 1W+ 445nm inside and I was fine. (do not quote me on that, it is just a bit of an example) As long as there is no direct contact of the majority of the laser's photons to the eye, no damage will be dealt.
 
Atomicrox

Atomicrox

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PWMing lasers doesn't make them much safer, unless you use a *very* high frequency.

OTOH I don't think it's that dangerous to use <50mW lasers to point at matte surfaces, but it would be very annoying if it's a 50mW green laser.

I think you could probably drive it low for 5mW. 20mW is definitely doable and not that annoying to look at.
 
cantthinkofone

cantthinkofone

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ive decided to just use an ebay DPSS 532nm. i know i could just say shite laser i got for 8 dollars but it sounds more cool when you call it as it is, a DPSS. i will still be building this 520 however im pushing for 80-90 mw instead of display safe.
 
Atomicrox

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You'll be hard pressed to find any safe 532nm lasers... Those pens have no IR filter and can go up to 100mW if you're "lucky".
 
cantthinkofone

cantthinkofone

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possibly so. i guess its just hope that the ir wont burn anyones retinas
 
Last edited:
hwang21

hwang21

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Well some lasers have extremely divergent IR beams, some have very focused IR beams... hard to say
 
Atomicrox

Atomicrox

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Test it out with an unfiltered camera. Cheap webcams are great for this.
 
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