Scotch Tape Emitter, cool tint or X-ray

elgarak

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- Duct tape removes warts :D

- The German-made Tesa tape (by Beiersdorf) can be used to store holographic images.

- I work with Ultra-High Vacuum systems for a living. There's nothing to suggest that LEDs would work any way different in a vacuum, but sometimes there are surprises (one of the projects I worked on was a ferroelectric waveguide. That thing worked well in atmosphere, but now the company making the waveguides was supposed to put it in a satellite. They tried it in a vacuum chamber. Stopped working after an hour or so. Turns out the waveguide property relies on ions on the surfaces of the material. The ions come from the air/moisture and get ionized by the ferroelectric properties. In a vacuum, the ions just evaporate away). Most production LEDs are a no-go, as the packaging is usually not made from vacuum-compatible materials and can have hidden air pockets. Besides, it's a lot more troublesome to feed cables from the outside to the inside than just slapping a window on the vacuum chamber and use just a normal lamp on the outside.
 

UberLumens

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very interesting elgarak thats a cool sounding job also. what do you use the chambers for?

didn't think about powering it in a vacuum, maybe a few solar panels and a low power led with no lens(same idea as a de-domed sst90).

After reading the article i had a 100 ideas on things to try, but of course no chamber.
 

elgarak

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very interesting elgarak thats a cool sounding job also. what do you use the chambers for?

didn't think about powering it in a vacuum, maybe a few solar panels and a low power led with no lens(same idea as a de-domed sst90).

After reading the article i had a 100 ideas on things to try, but of course no chamber.

We do photoemission spectroscopy -- blast samples with x-rays or UV (HeI, 21.22 eV energy, i.e. about 60 nm) and look at the spectrum of the electrons coming out of the samples. It's a surface sensitive measurement, since pretty much only the electrons coming from, oh, 50..100 nm deep are worthwhile. We need ultra high vacuum to keep the samples clean enough for a series of measurements. We then put a thin film of interesting materials on there, measure, more deposition, repeat. With this, we investigate the electronic structure of the interface between the original sample material and the film.

One system we're doing right now are CdTe solar cells and their back contact. The back contact we look into right now is NbSe (Niobium Selenide) that we evaporate in a special chamber.

Other things we do are organic or nano sized materials -- like the stuff used for OLEDs. We have built a quite cool deposition system ourselves, so that we can spray these materials from the liquid solution they are made in (in air) into a series of holes in the vacuum chamber. The holes connect a series of small chambers with better and better vacuum, until we reach the high vacuum where the material we deposit on resides.

To get back to lighting: We currently illuminate our chambers with 12 V tungsten incandescents. Those run pretty hot, and get in the way a lot, so we're looking for alternative LEDs. We found a supplier that makes LED lamps specifically for UHV (ultra high vacuum) systems -- essentially just a piece of plastic machined to fit on a standard UHV window, with 12 LEDs in it. Cost: $450 :eek: ! We call that the "UHV tax". So right now we bought LED strips from a car cosmetic store. 12 LEDs already wired up in a flexible plastic strip. $12. Still have to make a mount ourselves, but that's just time consuming.
 
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wes_wall

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You get the same effect from a bandaid or socks. Socks are more fun because you can do them over and over again. Also, try cracking an old fashioned plastic ice tray in the dark. All this is static discharge. One note, do these party tricks in the dark or in very dim light. Wait for your eyes to get adjusted and let the fireworks begin!
 

alpg88

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what does UH vacuum means??
i work with ac systems, when i evac. the sys or open it, i have to vacuum it before i fill it with freon, my vacuum is 29hg iirc, i was told that this is the most vacuum you can achieve on earth, what would be your UH on the same scale?
 

UberLumens

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man i would love to tour/take a look at all that equipment! amateur scientist all the way since i can remember, stuff like that is great to me

as for the chamber lighting. what kind of brightness/color do you need? those auto lights aren't much from what i have seen, maybe one of our custom builders can make you something more tailored(with no UHV tax :D)

EDIT: alpg88 UHV = Ultra High Vaccum, many bars of pressure held to a specific tolerance
 

UberLumens

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thanks, but it wasn't what i was asking for.

sorry read your post to fast, same scale, but much tighter tolerances held much longer.

to get a full true vacuum you need some special gear.

It like getting absolute zero you can make stuff cold, but unless you have special stuff your not getting close no matter "what the box says"

( if your googling says im wrong please correct)
 

elgarak

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Normal air pressure: 760 Torr pressure
Low Vacuum: 760 .. 25 Torr
Medium Vacuum: 25 .. 1e-3 Torr
High Vacuum: 1e-3 .. 1e-8 Torr
Ultra High Vacuum (UHV): 1e-8..1e-12 torr (Our base pressure is about 5e-10 Torr, but is usually higher since we do actually work in our system :D)

Vacuum better than that is called "Extremely High Vacuum", but that requires a lot of tricks and is usually found only in a handful of specialized labs around the world. UHV is comparatively common -- most research universities have a few labs each reaching that.

To compare: A typical space shuttle low earth orbit is about 1e-6 Torr. Hubble is a bit better: ~1e-8. The moon's surface is 1e-11 Torr. That still means 40,000 molecules per cubic centimeter. Interplanetary space has 10 molecules per cubic cm, interstellar space 1.

All those molecules zipping around may stick to surfaces, say, of our sample, which we want to keep as clean as possible. One metric is how long it will take for one atomic layer of unwanted crud to stuck onto our surface. In normal air, this time is in picoseconds, essentially immediately. In 1e-6 Torr vacuum, it's a minute. In 1e-8 Torr an hour. 1e-9, about 10 hours, or a workday, so that's something we can work with.
 

Illum

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I think this might revive the lost technology of Apollo age tape drives...get huge rolls of tape, load in an empty spool and unroll/reroll away, out of light? rewind the tape!
 

alpg88

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Normal air pressure: 760 Torr pressure
Low Vacuum: 760 .. 25 Torr
Medium Vacuum: 25 .. 1e-3 Torr
High Vacuum: 1e-3 .. 1e-8 Torr
Ultra High Vacuum (UHV): 1e-8..1e-12 torr (Our base pressure is about 5e-10 Torr, but is usually higher since we do actually work in our system :D)

Vacuum better than that is called "Extremely High Vacuum", but that requires a lot of tricks and is usually found only in a handful of specialized labs around the world. UHV is comparatively common -- most research universities have a few labs each reaching that.

To compare: A typical space shuttle low earth orbit is about 1e-6 Torr. Hubble is a bit better: ~1e-8. The moon's surface is 1e-11 Torr. That still means 40,000 molecules per cubic centimeter. Interplanetary space has 10 molecules per cubic cm, interstellar space 1.

All those molecules zipping around may stick to surfaces, say, of our sample, which we want to keep as clean as possible. One metric is how long it will take for one atomic layer of unwanted crud to stuck onto our surface. In normal air, this time is in picoseconds, essentially immediately. In 1e-6 Torr vacuum, it's a minute. In 1e-8 Torr an hour. 1e-9, about 10 hours, or a workday, so that's something we can work with.
thanks man.
that means (if i got it right) 1 torr =1 mmhg, 760torr=760mmhg,
go my vacuum is 29mmhg = 29torr,
that is low vacuum.
than all those ppl that told me you can't get higher than 29mmhg on earth lied to me, :mad:
 

elgarak

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thanks man.
that means (if i got it right) 1 torr =1 mmhg, 760torr=760mmhg,
go my vacuum is 29mmhg = 29torr,
that is low vacuum.
than all those ppl that told me you can't get higher than 29mmhg on earth lied to me, :mad:

Yup, 1 Torr = 1 mmHg. It's so ingrained in me that I use both mixed. Torr is easier to say. In writing, I mostly use mmHg. It's still the standard unit for vacuum pressures in the US (where I work). In Germany, where I got my PhD, it's mbar. Fortunately mbar and mmHg are close enough that the broad ranges (the number behind the e) are more or less the same.

Both are not SI units. Correctly, we should use Pa(scal). But no one does. Not even for scientific papers.

EDIT: It's absolute pressure. 0 = total vacuum, 760 mmHg = 1 atmosphere. In car circles, people often use relative pressure, with normal air pressure as zero, and measuring vacuum in mmHg underpressure. In this case, you have a maximum underpressure value for total vacuum of about 760 mmhG = 29.92 inHg. Inches of Mercury, not millimeters of Mercury. The standard air pressure unit for weather reporting.
 
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