strange fluid inside a rear projection tv i was pulling apart?

so i was disassembling a toshiba rear projection for the fresnel lense, and figured i'd pull the rest of it apart and see what parts i could salvage, i got to the gun assembly (i think its called that) and was pulling one of the guns to bits to salvage the lens mount and discovered there was some sort of liquid between the gun and the lenses, it smelt strongly like alcohol and burnt when i held a flame to it long enough, i got some on my hands and my hands started getting a burning sensation so i washed it off and stored it in an icecream container

can anyone tell me what the liquid is? why is it inside the tv/projection guns? 

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Wired_Mist3 years ago

It's for both heat dissipation and mostly optic clarity. I can't explain the science behind the Optics, I just know it works. (Sean's answer might be helpful)

Those filters are sensitive to heat, as is the "gun" it's self. My father had a nice Sony-RP and had a similar problem when the green filter got a bit toasty ! Just like the oil in your car, it is used to conduct heat away from Vital components. Only difference is rather then circulating it through a Rad, it just conducts the heat away (and to a heatsink)

see here for one brief explanation.

or >>

if the link tool is still broken. The idea, erm, one idea is to make the transmission path continuous to avoid internal reflection and refraction. (And... somewhat obviously, internally reflected and refracted light from a high intensity source is going to increase the heat capture internally, aside form loss of output intensity, ghosting, etc.)

For my purposes back in the wayback, it would have corrupted the velocity measurements and made them statistically irrelevant. Not too kosher when you're doing research for the US navy and are a patriot t'boot...

Meh, I'll buy that ! lmao sounds close enough to what I was thinking :P

I don't suppose you know how much light refracts in air Vs say, optic glass? I know heat plays a factor (like on a hot road) but I've never really looked at the number on this.

Index of refraction is 1 in a true vacuum. all other optical materials (afaik) have indices lower than 1 (range 0-1). Index of refraction is temperature dependent. That goes for glass or water or air or oil or any other transmissive material. The difference between optical and regular glass is in part that most "normal" optical glass is manufactured to maintain a consistent index of refraction, whereas normal glass exhibits variations. And the difference between the kind of uniform optical path that one might normally encounter in optics like this subject post,and the regular world, is that in the regular world, the index varies wildly based on various conditions like convective patterns, particulate intrusion, etc. whereas the uniform optical materials one might normally see in an optical window etc has a consistent index across its usable area. The specifics? No. Which air? What temperature(s). what pressure? what humidity? How much particulate count? ...

It's been quite a while since I was actively involved in an optics project, (aside from the trivialities of amateur astronomy) so my working skills are rusty. But the brain still works and the details are just a click or two (hundred ;) ) away or could be revealed by cracking open my relevant books...hmm... which are currently stored up in the attic in boxes.

As I recall... Air at a constant temperature pressure and humidity is usually fudge factored to ~1

I do Love details ! lmao

That perfectly answers my question; thanks for the well crafted answer :D

sheesh, I got curious... I guess you're right about it's dual purpose

btw, didn't think of it as a cooling fluid. That's interesting if true.

WayneR441 year ago

There was fluid coming out of this rear projection tv too... Seemed to be harmless though. And it was not flammable..! Don't ask how we know. :)

i think it must be silicon

AuvyM2 years ago

ethylene glycol and water

Typically, rear projection TV manufacturers use an optical grade (99 percent pure) 70 percent mono denatured ethylene glycol and 30 percent glycerol/glycerine. The exact mixture may depend on the product and manufacturer. It is extremely toxic but degrades rapidly. It should be disposed of properly. Toxic skin exposure is rare as it is not absorbed easily through the skin. Dangerous as it appears sweet. Avoid this stuff!
Form CDC:
ROUTES OF EXPOSURE: Systemic ethylene glycol toxicity can occur through ingestion. Breathing ethylene glycol vapors may cause eye and respiratory tract irritation but is unlikely to cause systemic toxicity. Ethylene glycol is poorly absorbed through the skin so systemic toxicity is unlikely. Eye exposure may lead to local adverse health effects but is unlikely to result in systemic toxicity.

seandogue3 years ago

At a guess, it's probably an index matching fluid (fluids are sometimes used to change or otherwise guarantee the index of refraction between two mediums, ensuring the optical path behaves as the engineers intended. ).

We used to use a mix of several oils at a fixed temperature to match the index of refraction in a scientific instrument used to precisely measure fluid speed back when I was a tech at a local university in the 1980s. In that case, keeping the temp constant was a big problem, but that's another story for another ramble.

etlerd3 years ago