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"The Grayser"

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PostPosted: Sun Mar 11, 2007 1:05 pm    Post subject: "The Grayser" Reply with quote

Take one 16X DVD burner laser diode, diode housing and lens, a 2.7 Ohm resistor, 100uF capacitor... all supplied by Dr. Lava in one of the coolest group buys ever on Candlepowerforums. Add in a few cheapie project pieces from Radio Shack, two AA batteries, and we've got the Grayson laser... a.k.a. "The Grayser".

One fateful day, I was perusing CPF when I came across a post in the group buy section. It was for high power red laser diodes at such a ridiculously low price, it couldn't be passed up. I've always liked lasers of all types (there are many). They're fascinating, and just plain cool. The idea of building my own, especially one that completely obliterates any low cost, red laser "pointer" you can find, sucked me right in, and has since blossomed into a full-fledged part of my addiction to modified portable lighting. I'm now fully "into" lasers, and the steep learning curve that comes with them.

In addition to supplying all the crucial parts, Dr. Lava made it extra easy for us by doing the testing necessary to determine the correct resistor and cap values. The supplied "kit" is designed to run the diodes slightly below spec, which allows use of a super simple circuit to keep them within a safe range, helping them to live a long and healthy life. At this power, the heatsinking provided by the diode and lens housing is quite adequate, and there's enough output to pop a black balloon in approx. 1/2 second @ 4ft. away, and light magic marker blackened matches, in about a second @ 1ft. Haven't tested yet at longer distances.

I also have yet to measure the voltage and current at the diode, as I'd have to unsolder a connection or two to get the meter in series. I also do not have a Coherent laser check. Therefore, the numbers are estimates based on Ohm's law for the current, and for optical output, a mA vs. mW chart done by the Dr., based on his testing. On Energizer E2 lithiums, my setup should be running a hair under 120mA of current, and outputting approx. 55 - 60mW of optical power... at least when the batteries are fresh. This, for a total investment of under $25!... hehe.

The datasheet for these diodes (made by Rohm) rates them for 80mW continuous wave @ 2.4V (240mW pulsed). Some dudes on CPF though, are really pushing these things to the limit... running current through them WAY beyond spec, trying various cheapie booster boards from LED flashlights, using 3 rechargeables instead of 2 primary batts., etc. There have been some casualties. However, many have lived! Some even after fairly torturous abuse. Seems these diodes can handle a lot. Can't say how much longer before a few more turn into expensive, dim, burnt out LED's, but hey, we're having fun.

As for mine, I definitely want to up the output to compete with, say, a Wicked Pulsar P100 costing over $200 with shipping. Devilgrin A proper, constant current laser driver such as the EU-38 for about $15 will certainly do the trick. The more complex, and more expensive ones are not necessary here. In fact, I'll be keeping an eye out for the latest developments involving experiments using the booster board from a super cheapie, LED flashlight called the "Elly". I think the whole flashlight is like, $5.50... lol. The EU-38 gives me current control though, so we'll see.

So, let's see some pics, shall we? Don't forget your safety glasses!

The Grayser. That's right, we ain't playing here. The switch goes forward for constant on, center is off, and you pull it back and hit the red "fire" button for momentary operation.

Out of focus. Gotta' retake this shot.

The business end.

The other business end.

A look inside the magical box of amplified coherent light.

Cap, resistor, switches.

The diode/lens housing is sitting on a small heatsink, in which I channeled a bit out of the top for the housing to nestle in, and attached the two with Arctic Silver heat conducting epoxy. Cool stuff... no pun intended.

How many times can you look into a laser beam? Twice!! Cracking Up

And there it is in it's current state of development. Stay tuned for when the real danger, and therefore, fun begins. Muah haa haa haa haaaaaa!
I lick, therefore I am.

"They come here to see him go crazy or something. They don't realize there's notes involved."
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Joined: 11 Oct 2005
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Location: Long Island... formerly Sri Lanka, until "the incident".

PostPosted: Mon Mar 12, 2007 12:53 am    Post subject: Reply with quote

lmao That's fucking cool!!! heh Definitely want to see some action shots of that puppy...
Just Walk Away

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PostPosted: Wed Jul 04, 2007 5:40 pm    Post subject: Reply with quote

WhyteChocolate wrote:
Definitely want to see some action shots of that puppy...

Well, it'll be with me at the Farm Party! I want to do some very long distance testing with it.

Unfortunately though, it died yesterday. Hit the button, saw the flash, and it instantly went from inexpensive laser diode, to an expensive, very weak LED. Some background as to why...

Where I stated above, that this laser should be pumping out about 60mW, is completely wrong. While re-doing the switch connections not long ago, I took a current reading... 306mA! Well, holy bejeezus! No wonder it was so damn powerful. Even on a dry, crisp night, the beam was bright and strong. According to a powerplot done by the dude who organised the diode buy, at that current, it was likely putting out around 170mW... twice the diode's rated output. It was only a matter of time before the mirrored facets of the resonant cavity developed a weak spot, then kablammo!

The good news however, is I have backup diodes. Devilgrin I'm going to put the next one through the same torture long enough for the Farm, and then step it down a bit by using alkalines instead of lithium.

I feel bad for my nice 16X Rohm reddie though... still in mourning. Yesterday, I wrote "Requiem for a dead diode". aka. "Laserium Defunctorum"... to be sung in Gregorian Chant style.

Desiderium laserium concubius
Evoco genero
Refero referre rettuli relatum
Me laserium defunctorum

My Latin completely sucks, but 1,000 cool points to whoever translates it! Cool
I'm an excellent driver... Of course I don't have my underwear. I'm definitely not wearing my underwear

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