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ajward
12-14-2011, 10:51 PM
The newest distraction to keep from completing something else.
http://bit.ly/t8wyJP

Recently I picked up a few laser diodes (1000mW @ 808nm). Not wanting to just plug them into a breadboard and apply power, I built an aluminum enclosure with a moveable target. The other half of the enclosure goes on before applying power.
Power comes from a single "D" cell through a wirewound 1 ohm 10W resistor.
Still some mechanical work to be done... nuts & bolts stuff.
I'll use the Homework Board to pulse the diode through the relay on the breadboard.

Getting into somewhat uncharted territory, but should be fun!

@

$WMc%
12-14-2011, 11:17 PM
Might make for some cool Christmas decorations/displays

GordonMcComb
12-15-2011, 12:20 AM
Recently I picked up a few laser diodes (1000mW @ 808nm).

Wow. These are EXTRAORDINARILY unsafe without proper precautions like near-IR blocking safety goggles, and even then they're dangerous. That wavelength is just beyond normal human vision. The light appears very dim, giving a false sense that it's not a powerful beam. It's also not so far into the IR that your eyes won't focus the majority of the beam right onto your retina . Even the specular reflections from a 1 watt laser can enter the eye, causing permanent retina damage in seconds. You won't even realize it.

I did exactly this over 20 years ago when experimenting with lasers far less powerful than this one. I have permanent "floaters" in both eyes because of it. Though my opthalmologist remains skeptical, I believe it's also the cause of my monocular diplopia in the most affected eye. It took several years for that condition to fully manifest, but it's permanent. It's a condition you do NOT want.

So, my advise is to send them back and get <10 mW visible red lasers. But if you just have to have these 1W near-IR lasers, get blocking goggles that cover that wavelength (they aren't cheap, usually over $100) and don't experiment with anyone else in the room, including animals.

-- Gordon

ajward
12-15-2011, 12:32 AM
Wow. These are EXTRAORDINARILY unsafe without proper precautions like near-IR blocking safety goggles, and even then they're dangerous. That wavelength is just beyond normal human vision. The light appears very dim, giving a false sense that it's not a powerful beam. It's also not so far into the IR that your eyes won't focus the majority of the beam right onto your retina . Even the specular reflections from a 1 watt laser can enter the eye, causing permanent retina damage in seconds. You won't even realize it.

I did exactly this over 20 years ago when experimenting with lasers far less powerful than this one. I have permanent "floaters" in both eyes because of it. Though my opthalmologist remains skeptical, I believe it's also the cause of my monocular diplopia in the most affected eye. It took several years for that condition to fully manifest, but it's permanent. It's a condition you do NOT want.

So, my advise is to send them back and get <5 mW visible red lasers. But if you just have to have these 1W near-IR lasers, get blocking goggles that cover that wavelength (they aren't cheap, usually over $100) and don't experiment with anyone else in the room, even animals.

-- Gordon

Gordon... many thanks for your input. I do have goggles. The laser will be enclosed in an aluminum housing with light blocking baffles when powered. I also have a wood partition to place between me and the platform. Also printed a large "Laser in operation" sign to place on the door to my room.

Just my geek side.

@

Mike Green
12-15-2011, 12:35 AM
Ditto on safety. You can get goggles that won't let you see at all through them or you can get goggles designed to block specific wavelengths that let through other wavelengths so you can mostly see what you're doing. I've got an IR laser device that only produces 30mW of IR light (830nm) and need to use the high end protective goggles made for that wavelength.

GordonMcComb
12-15-2011, 12:52 AM
I do have goggles.

What kind of goggles to you have? The 808 nm mainline makes me think these were lasers intended for Yag frequency doubling. Even without the crystal installed, this type of laser creates additional lines, so you really need googles that block most light above 600-650 nm. If the crystal is present, they also need to block 532 nm. This kind of eyewear is the most expensive of all -- looking at the Thorlabs site the closest match costs $300.

Personally, now that I'm older and have eye troubles that cannot be reversed, I wish I hadn't felt so invincible as I did in my youth. I could have done the same experiments with a much less powerful laser, and one in the visible light spectrum. Being 1000 mW (class 4 for sure) + near-IR is a double whammy. Just as one last reminder, it'll take maybe 10 milliseconds of direct eye exposure of that beam to cause a permanent lesion on the retina, plus unknown damage to the cornea that later in life may cause cataracts. You likely won't even feel it, and other than maybe being light-headed for a brief time, won't know until much later there's a problem.

Please be more than safe!

-- Gordon

frank freedman
12-15-2011, 01:29 AM
The newest distraction to keep from completing something else.
http://bit.ly/t8wyJP

Recently I picked up a few laser diodes (1000mW @ 808nm). Not wanting to just plug them into a breadboard and apply power, I built an aluminum enclosure with a moveable target. The other half of the enclosure goes on before applying power.
Power comes from a single "D" cell through a wirewound 1 ohm 10W resistor.
Still some mechanical work to be done... nuts & bolts stuff.
I'll use the Homework Board to pulse the diode through the relay on the breadboard.

Getting into somewhat uncharted territory, but should be fun!

@

1000mw?!? WTF are you thinking? We used to use 820 nm solid state lasers in 3M medical hardcopy cameras. I doubt these were even 10mw let alone 1w. Most of the path was fully enclosed, interlocked out the wazoo and I still wore the goggles. If this is uncharted territory, turn back; there be monsters. And you will not know you have been bitten until the damage is done. Go lower power and visible; if you get hurt please do not post the details.

ajward
12-15-2011, 01:54 AM
Wow!

I have goggles rated for the 808nm wavelength. The diode will not be powered without the enclosure being closed. The enclosure has complete light baffles. The object is to see what laser "light" can do to various materials on the target at differing distances. Fully enclosed! On the other side of a wall!

Amanda

GordonMcComb
12-15-2011, 03:05 AM
We used to use 820 nm solid state lasers in 3M medical hardcopy cameras. I doubt these were even 10mw let alone 1w.

Unfortunately these are all over the Web (though on many the actual output is far less than 1W). They're imported from China and originally intended to make green laser pointers. Leave out the Yag, and you've got a very bright and very dangerous IR laser.

Here's a guy demonstrating burning a match stick using a handheld 1000 mW pointer. Notice the camera picking up the specular highlights as the beam bounces off objects:

http://www.youtube.com/watch?v=ZokrnlU7eCE

Much more of this and he'll be needing to get some seriously thick reading glasses real soon!

Anyway, I think given Amanda's description of her experiment she's taking all the right precautions.

-- Gordon

Phil Pilgrim (PhiPi)
12-15-2011, 03:13 AM
Much more of this and he'll be needing to get some seriously thick reading glasses real soon!
More like a red-tipped white cane. No amount of extreme focusing will bring burnt cones and rods back to life.

You don't have to stare into a laser to suffer eye damage, boys and girls. An errant reflection from one is all it takes.

-Phil

Peter KG6LSE
12-15-2011, 03:40 AM
http://farm3.staticflickr.com/2020/2236087758_b4a9093260.jpg
I did LEO ( laser Electro-optics) as a "minor " in my college .
My max I run here with a open beam on a bench is 100mW EVER .and I wear a thick labcoat and googes ..

(no point wearing "rose glasses" when fumbling with setup) ..
The issue is until you use it . the reflections are not obvious as IR you cant see.. If you need to . use a HENE in the same path to "show" what the beam is doing. Please ..

BTW the OLD ANSI CLASS system is not in use anymore FYI .
http://en.wikipedia.org/wiki/Laser_safety#Revised_system
OTOH I own a Nd:YAG and a few 10s of watts 808 Bar Diodes .
As long as you cant encounter a beam .. the laser is OLD class 1 ... Heck the college engraver is is CLASS1 as its interlocked !..( 30 W co2) .


Peter...

frank freedman
12-15-2011, 04:06 AM
Unfortunately these are all over the Web (though on many the actual output is far less than 1W). They're imported from China and originally intended to make green laser pointers. Leave out the Yag, and you've got a very bright and very dangerous IR laser.

Here's a guy demonstrating burning a match stick using a handheld 1000 mW pointer. Notice the camera picking up the specular highlights as the beam bounces off objects:

http://www.youtube.com/watch?v=ZokrnlU7eCE

Much more of this and he'll be needing to get some seriously thick reading glasses real soon!

Anyway, I think given Amanda's description of her experiment she's taking all the right precautions.

-- Gordon

Gordon, I hope your are right about precautions. Not seeing what she has in the box, and knowing what some are doing via uTube drove the initial line of my post. If there is any sort of alignment of path, how will it be done in the box? All it takes is one time illuminating the wrong reflective surface and one negative outcome results; damage probably permanent. The real 4 alarm statement in her post for me was "this is uncharted territory" without the benefit/mention of an experienced mentor. And that is not a good precaution to leave out when playing with this level of personal hazard.

Frank

Loopy Byteloose
12-15-2011, 09:07 AM
Hmmm.........
Reminds me of my DIY Xray machine made for old vacumn tubes and inspired by an article in Scientific American's Amature Scientist.

It really doesn't matter if you are into Xrays or Lasers, if you cannot see what is doing the damage - it is a huge hazard. I'd love to buid a DIY laser cutter, but I also know that I am sloppy enough to not become involved in such a project.

Heater.
12-15-2011, 11:56 AM
Back in uni circa 1979 I visited a friend of mine in his lab. He was studying for a masters in laser physics. At one end of the lab was a big laser tube at the other was a calorimeter to measure the lasers power output. While the calorimeter was out of the way being tweaked the laser beam ran into a "safety" target, a big red house brick on the bench. That brick was smoldering and a hole was being slowly burned through it!!. The beam itself was invisible.

I have no idea which side of the visible spectrum that laser was operating on but subsequently I have always wondered why I can still see. Any ideas what it may have been?

GordonMcComb
12-15-2011, 05:18 PM
Maybe it was a C02 laser. They're relatively inexpensive and put out a lot of watts. They operate well into the IR range. The damage to your eye, had it been in the path, would have been to the cornea -- basically an instant cataract. The aqueous gloop in your eyes stop that wavelength.

But there are other high-power lasers that produce IR beams, such as the Nd types, like Nd:Yag. In 1979, it likely was not a UV laser due to their very high cost at the time.

-- Gordon

ratronic
12-15-2011, 06:48 PM
I built my first laser in 1982 a helium neon 1mw(still have it!) and used to take it to the drive in theaters (remember those?) and shine it on the screen (during intermission) the kids were amazed as there were not to many lasers back then. Today I have a 300mw green laser thats to bright to look at the dot on a white wall and if the wall happens to be wood paneling it starts to smoke! Danger Will Robinson Danger!!

GordonMcComb
12-15-2011, 07:19 PM
Serious old skool:

http://books.google.com/books?id=0uSILcWppmwC&pg=PA130&source=gbs_toc_r&cad=4#v=onepage&q&f=false

As I recall the tube put out about 2 mW. It would run about five minutes before the 9-volt battery was drained.

Cost to build in 1989: about $125. Cost to build one today using a laser penlight module: about $3.

-- Gordon

Martin_H
12-15-2011, 07:19 PM
While I've been curious about what a higher powered laser diode can do, I don't trust myself to not get sloppy. So I avoided them as unlike a table saw where the noise and spinning blade focus the mind, these things are silent except for the whir of the power supply fan. Keeping it in a sealed box that has some sort of power supply interlock seems on way to avoid getting careless.

But if you want to see careless, You Tube has a plethora of videos from people who have no idea of what they're fiddling with. Not just lasers, but taking the magnetron tube out of a microwave, confining liquefied gases, etc. One minute into the video below he lights a cigarette in his mouth with a 200 mw laser, while not wearing goggles! I've seen even crazier videos like people driving around while shining a 1 watt blue laser out their car window.


http://www.youtube.com/watch?v=pKc3e1rjXKs

Wow.

ajward
12-15-2011, 07:27 PM
I do appreciate y'alls concern and I have given this a decent amount of thought.

Let me go over the layout again...
The laser is mounted in an .040" aluminum box with a snug fitting cover... secured with sheet metal screws. Inside is a moveable target on which I'll hang various materials to test.
Any places where the beam might escape have been sealed with opaque material.
I use a jumper system to apply/lockout power. One shorts the DC input before any other components. The second shorts the +/- leads of the diode after other components. When these are removed, I can plug in the battery pack. Not quite ready yet. Now those two jumpers must be reinserted... supply positive to diode positive and supply negative to diode negative.
Then set up the divider between the test chamber and circuit board, look away, press the button and count to 5... or maybe 10.

After that... disconnect power, install the jumpers in the shorting position, unscrew the cover and see what happened inside!

It's kind of tedious (about 4-5 minutes between shots), but I think it's safe enough. I mean... sure I could bypass all the steps, apply power directly and watch the beam... but I don't! :blank:

Anyhow... Getting ready to apply power for the first time. Film at 11.

Amanda

xanatos
12-15-2011, 08:35 PM
I'll echo the safety sentiments here - even with my goggles, I'm still uber-paranoid of reflections, and I won't even touch IR. I've been experimenting and playing with lasers in the 200 - 500mW range for about 5 years now (red 635nm & "BluRay" 405nm items harvested from 20x DVD burners).

So if you've REALLY got the idea that these things can lead to an instantaneous and irreversible, premanent, life-long destruction of your visual system via any of a dozen mechanisms... then be careful, have fun and be sure to post video!

Dave

$WMc%
12-15-2011, 11:01 PM
I would put a small camera in the "safety box" and watch what happens to the target on a monitor.
'
Please keep us up to speed with your test results.

Peter KG6LSE
12-16-2011, 12:07 AM
I do appreciate y'alls concern and I have given this a decent amount of thought.

Let me go over the layout again...
The laser is mounted in an .040" aluminum box with a snug fitting cover... secured with sheet metal screws. Inside is a moveable target on which I'll hang various materials to test.
Any places where the beam might escape have been sealed with opaque material.
I use a jumper system to apply/lockout power. One shorts the DC input before any other components. The second shorts the +/- leads of the diode after other components. When these are removed, I can plug in the battery pack. Not quite ready yet. Now those two jumpers must be reinserted... supply positive to diode positive and supply negative to diode negative.
Then set up the divider between the test chamber and circuit board, look away, press the button and count to 5... or maybe 10.

After that... disconnect power, install the jumpers in the shorting position, unscrew the cover and see what happened inside!

It's kind of tedious (about 4-5 minutes between shots), but I think it's safe enough. I mean... sure I could bypass all the steps, apply power directly and watch the beam... but I don't! :blank:

Anyhow... Getting ready to apply power for the first time. Film at 11.

Amanda


Its the same interlock as on a co2 epilog .
should be OK


but I do hope you Don't Poof that diode with a over simple Power supply . :smile:..

Peter.

ajward
12-16-2011, 12:19 AM
I would put a small camera in the "safety box" and watch what happens to the target on a monitor.
'
Please keep us up to speed with your test results.

Good idea, but the current enclosure is a bit small for my current cameras, tho' I have a couple of old web cams I might take apart. (Thinking cap on!)

ajward
12-16-2011, 03:29 AM
As things wind down for the night, thought I'd update today's experiments.
First... my eyesight is intact... well, as intact as it was before!

I ran several tests with different materials with ~10 second exposure.

1. Aluminum foil - No effect at any distance.
2. White paper - Ditto.
3. Section of PC board... copper or board side - Ditto.
4. Black conductive foam @ ~4mm - Some melting noted!
5. Black card stock @ ~ 2mm - Burned through!
6. Black plastic cap for ink pen @ 1, 3, 5mm - Burned through!!!!

http://bit.ly/uRncw3
Front of the black card stock sample

http://bit.ly/vcXXRP
back of the card stock sample

http://bit.ly/uPZbWb
One view of my black pen cap

http://bit.ly/vbVhJW
Another view of the poor pen cap

Time to call it a night. More tomorrow.

Amanda

PS - This isn't a focused laser. Just a bare diode. Without some sort of focus I don't think it's going to have much effect on the target materials beyond about a centimeter. However, focusing is down the road a bit. Next up is a better power supply.

Heater.
12-16-2011, 09:22 AM
Gorden,

Yes, CO2 IR laser rings bells in my mind now.

In 1993 or so I built a Helium Neon laser from a kit by Maplin Electronics in the UK. I used it to make white light holograms in my kitchen. My young lady wrote up the theory and technique as part of here studies at technical college. Eventually she rewrote it as an article for the Maplin Electronics magazine. I knew nothing of this so it was quite a surprise to pickup that magazine in a store and find pictures with my kitchen floor in the background in there.

tobdec
12-16-2011, 02:50 PM
SAFETY SAFETY SAFETY!!! My idiotic cousin once knocked him-self out with a similar laser...except his was green. They can be a blast, I once tried..unsucessfully, to build a laser than could knock birds outa the sky, I caught some leaves on fire lol.

$WMc%
12-17-2011, 03:43 AM
ajward
'
This is cool

xanatos
12-17-2011, 04:34 PM
AJWard - you'll see massively different results when you focus the beam. The output from the raw diodes has a wide divergence (some as high as 70 degrees) - with good IR optics (which are a little more expensive than regular visible optics) a watt of IR will pop holes in things very quickly. A watt of visible blue (445nm from a projector) does as well! :-)

Dave

ajward
12-18-2011, 09:01 AM
AJWard - you'll see massively different results when you focus the beam. The output from the raw diodes has a wide divergence (some as high as 70 degrees) - with good IR optics (which are a little more expensive than regular visible optics) a watt of IR will pop holes in things very quickly. A watt of visible blue (445nm from a projector) does as well! :-)

Dave

Agreed. I'm shooting directly out of the diode and at a distance of 5mm the beam has spread out to about 4mm.
Looking at some enclosures and lens systems and, as you say, they aren't cheap. Not a show stopper, but I need to think a bit before I hit the "purchase" button. :-|

Amanda

xanatos
12-18-2011, 12:32 PM
IR optics are hard for two reasons - their long wavelength necessitate different optical properties of the glass/plastic, and (for me the biggest pain in the neck) you can't focus visually, you actually have to get the right lenses and distances to start with. Another reason I like working in the visible spectrum - makes it easier to just try stuff with the boxes full of lenses and FS mirrors I have. Interested to hear what you use. Are you going for a collinated beam, or just a tight focus at the target zone?

ajward
12-19-2011, 12:49 AM
IR optics are hard for two reasons - their long wavelength necessitate different optical properties of the glass/plastic, and (for me the biggest pain in the neck) you can't focus visually, you actually have to get the right lenses and distances to start with. Another reason I like working in the visible spectrum - makes it easier to just try stuff with the boxes full of lenses and FS mirrors I have. Interested to hear what you use. Are you going for a collinated beam, or just a tight focus at the target zone?

Still researching what is out there. I'd like to go with a collimated beam, since I want to study the effects at various distances.

Amanda

xanatos
12-19-2011, 01:03 AM
So yes, you're going to need good stuff to start with. Have you discovered Laser Pointer Forums yet? http://laserpointerforums.com/ There is a HUGE amount of VERY good info up there (some of it from me!) - you can find what you need there, the forums are organized by - among other things - wavelength!

Be forewarned - we've got it MADE here on the Parallax forums. Laserpointerforums.com is like - I don't even know how to describe it - but there have been and probably still are absolutely EPIC flame wars that erupt over there that have nothing to do with the beams! A lot of personality issues and some very sensitive folks who blow up often. If you step carefully you can find resources there however that you couldn't find anywhere else. Lots of years of experience, ranging from some very creative and dedicated hobbyists all the way up to post-doctorial professors of quantum physics and optics...

Happy hunting!

Dave

GordonMcComb
12-19-2011, 03:39 AM
Still researching what is out there. I'd like to go with a collimated beam, since I want to study the effects at various distances

You can use your cell phone camera to visualize the beam (but do so with your goggles). There shouldn't be much absorption with a pure white card.

The problem with adding optics for a laser with this kind of output is that you must keep them scrupulously clean. It would be best if you experimented with a lower wattage laser -- something <10 mW, and then when you discover what works, you can move the optics to the high power laser. Otherwise, in all the handling of the optics you can very easily crack or discolor the elements.

Could you post a picture of the diode you have? Or do you have the Web site you got them from? You might actually have some optics in there already, unless it's a bare diode, which doesn't seem likely from your description.

The fact that the burn through on the pen cap is rectangular says there's no beam-shaping optics. Ideally you want a nice gaussian dot, not a rectangle. Laser diodes naturally produce a rectangular beam because of the way the chip is cleaved inside, but the majority of the really nifty laser experiments need a shaped beam that's round, and includes virtually no nulls across the beam profile (so-called TEM00 mode).

-- Gordon