Temperature on the mirror surface

This is the place to discuss DLP projectors, UV Lasers, Galvanometers, LCD screens and similar display devices. Also discussed are optics in general.
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Kilh
Posts: 30
Joined: Sat Aug 16, 2014 10:32 am
Location: Berlin, Germany
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Temperature on the mirror surface

Postby Kilh » Fri Feb 06, 2015 4:03 pm

Hey guys,
I'm finally at the point where I sourced most of the parts for my bottom-up DLP and am currently working on part after part. I'll be printing a lot of elements in PLA (where it makes sense) as I don't have a CNC router available.

Right now I'm making some first drawings for a 45° (or maybe adjustable) mirror mount, but I was wondering if I should be worried about the temperature on the mirror. Obviously the projector (Acer) get's pretty hot, but will the mirror just deflect everything and stay around air temperature? Of course I could cool it from behind, but if the mirror is above 70°C most of the time I'd probably be better off going with a AL construction right away.

Could someone with a mirror build give me some insight? Anyone using PLA or ABS parts as mirror mount?

Thanks!

ggherbaz
Posts: 3
Joined: Thu Dec 25, 2014 11:38 pm
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Re: Temperature on the mirror surface

Postby ggherbaz » Sat Feb 07, 2015 1:30 pm

Hello,

I'm working also on a DLP printer but top down, I'm using PLA for any part that might end up in contact with the resin. I don't think it is a good idea to cool the mirror but at the same time I don't think it will get hotter enough to melt the PLA part. But since it will not be in contact with the resin you can print it out of ABS or polycarbonate (if you can print it) another material could be nylon. I print with Taulman bridge and although is a pain, it will definitely handle the temperature.

Good luck.

Scatterplot
Posts: 119
Joined: Mon Jan 12, 2015 12:09 pm
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Re: Temperature on the mirror surface

Postby Scatterplot » Mon Feb 09, 2015 12:38 pm

I doubt you'll have any issues with heatup, but if you're worried about it just get a little $10 12V fan blowing on it. There's no way it would heat up much at all with a tiny fan on it.

The light itself won't heat it up much; I don't know what the efficiency is of a standard front surface mirror, but it's gotta be high. Heck, even at 99% efficiency and I dunno, 200 W of light coming out (no idea if that's right or not but it's in the ballpark) you're only going to absorb 2W of power into the mirror. Hardly enough to worry about.

If your exhaust from your projector is blowing directly onto your mirror, you might get some warmup, but that can be solved by directing the exhaust somewhere else with a little flap.


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