
Simple Homemade TEA Laser (2007) - hamilyon2
http://www.sparkbangbuzz.com/tealaser/tealaser7.htm
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jpm_sd
(2007)

This is really clever! But it looks incredibly dangerous and probably emits an
enormous amount of RF noise.

The article never says what "TEA" stands for:

[https://en.wikipedia.org/wiki/TEA_laser](https://en.wikipedia.org/wiki/TEA_laser)

Tranversely Excited Atmospheric

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teekert
Asking for a friend, would such a thing disrupt the connection between his
neighbor's phone and said neighbor's Bluetooth speaker when he puts it next to
his fence in the garden?

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learc83
A spark gap generator would probably work better for that, but jamming is
illegal.

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teekert
Yeah I told that friend, but he feels that constantly providing background
music for your neighbor's lives should also be illegal. He's looking for a
more secluded house as well.

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abtinf
> constantly providing background music for your neighbor's lives should also
> be illegal

In most areas, it is often illegal, violates an ordinance, or is considered a
tort.

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sammycdubs
I always get really nervous every time I see the words "homemade" and "laser"
in the same sentence.

I had to take a laser safety workshop in college and the stories of accidental
blindings still haunt me. Those were from people who worked with lasers for a
living, so god knows what people messing around with them in their garage can
do.

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lisper
A very cool project, but this author is much to blase about safety IMHO. UV
lasers can blind you -- or, even more to the point, other people -- in an
instant if you aren't careful. And they can do so across long distances. You
should treat them with the same respect and caution that you would a firearm.

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aj7
Here’s how to read this post.

“Any atmospheric pressure linear spark with a field greater than about 10kV/cm
will show stimulated emission from nitrogen.”

This type of laser design is a well-known curiosity. It is not useful or
reliable, and always winds up on a shelf somewhere, or in the trash.

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blincoln
I'm really happy it was posted here, since I've never heard of this effect. Do
you have some further reading on the "not useful or reliable" aspect? This
site, for example, lists multiple applications for them:
[http://technology.niagarac.on.ca/people/mcsele/lasers/Lasers...](http://technology.niagarac.on.ca/people/mcsele/lasers/LasersN2.htm)

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blincoln
It's especially interesting to me because (as the article points out), it
doesn't require any really exotic equipment or skills to build one. I'm a
little surprised no one built one long before helium-neon lasers.

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terramex
If you are more of a video person, here is 5 minute video from _styropyro_ of
him explaining and building one:
[https://www.youtube.com/watch?v=1psxE4NlECQ](https://www.youtube.com/watch?v=1psxE4NlECQ)

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non-entity
I found his videos just yesterday! I was watching a video about an extremely
high powered laser he ended up burning stuff with, and was incredibly tempted
to get my hands on one till he noted how they try to keep that stuff away from
hobbyists lol.

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blincoln
It's not that hard to get ahold of reasonably high-powered lasers. IIRC, one
of the ones he used was ordered direct from China, sold as a tattoo remover.

If you decide to experiment with them, please be very careful, and buy proper
eye protection from a reputable supplier. There are a lot of garbage goggles
out there that don't actually filter out the parts of the spectrum that they
claim to. I've seen this myself with some alleged UV goggles that were the
same shade of green as my actual UV goggles, but didn't filter UV light. IIRC,
in the tattoo remover video, he finds the same thing with the useless "safety"
goggles that that laser included.

If you have proper laser safety goggles for the type of beam you're working
with, you probably won't be able to see the beam, which takes some of the fun
out of it. Years ago, I saw a video of a folded-optic welding helmet that put
HDR imagery on displays inside the helmet, so the eyes weren't even exposed.
That would be an ideal approach for lasers, IMO, but I can't even find the
video now, let alone DIY plans or an inexpensive commercial product.

It's the 21st century, but you still can't get the replacement eyes that 80s
cyberpunk novels promised us. It's very easy to lose some or all of one's
sight when experimenting with lasers. Back around 2010, I was about 3/4 of the
way through building a laser pistol out of a DVD writer diode and some custom
electronics when I realized that even in the best case scenario, it wasn't
worth risking my eyesight, so I abandoned it before going from the breadboard
phase to the "fits into a pistol form factor" version.

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sjnair96
Very cool. Reminds me of the times in middle/high school when I used to hunt
down computer repair shops and scavenge old or spoilt dvd/cd drives to build
lasers. The diodes harvested from drives that could write to disks were
powerful enough to burn through black tape and even light matches! All you
needed was an LM317T voltage regulator and a housing for the diode if my
memory serves my correctly. Fun times, as long as you stayed safe :)

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Loughla
Death Ray Lasers are what we called those in high school. They were
fascinating projects because they managed to bring together the computer geeks
and the gear heads in shop class.

Because everybody likes setting things on fire with lasers!

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JKCalhoun
TEA laser is a new term for me. It resembles the Nitrogen UV laser I have
wanted to build since I was a teenager and found the article in Scientific
American's "Amateur Scientist" column.

"An Unusual kind of gas laser that puts out pulses in the ultraviolet"
Scientific American, Amateur Scientist (June 1974)

This guy references it with regard to his TEA laser as well:

[https://www.cornellcollege.edu/physics-and-
engineering/pdfs/...](https://www.cornellcollege.edu/physics-and-
engineering/pdfs/phy-312/chad-compton.pdf)

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mabbo
This seems like a fun project, but I don't really understand what's going on
here.

I see a bright light, a lot of metal and electronics, and then what appears to
be a laser point. Scientifically, what's going on here?

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_Microft
From what I understand, there is a discharge along the length of the
electrodes which would excite the medium (air) in the gap. Now photons are
being emitted randomly in all directions. This means also _in direction along
the gap_. This is important since these photons will interact with more of the
excited medium and thereby stimulate emission of additional photons, leading
to 'lasing'. As long as there are excited molecules (or atoms) left, this is a
self-amplifying process. (Lasers are basically clever contraptions to keep
these excited states populated)

Notice that there is no resonator with mirrors at each end as you would see in
other lasers.

It is also a UV laser which means you can not see the beam without it
interacting with a substance that can convert UV to visible light. That's
dangerous because you could inadvertently look into the beam (via reflections
from somewhere in the lab!) and take eye damage.

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sriram_malhar
sign outside a physics lab:

"Don't look at laser through remaining good eye"

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ginko
And there I was hoping this would be about using tea as a gain medium to make
a laser. Green tea is slightly fluorescent, right?

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_Microft
How I would go about this: if you are not interested in learning about dye
lasers yourself, I would find a specialist working with dye lasers on Twitter
and ask them to settle "an argument with a friend" that green tea does not
work as gain medium. Then wait and hope that you have nerd-sniped them. With a
bit of luck you can read a paper about the topic one day. ;)

