Inexpensive Front or First surface Mirrors

[tgreenwood]

Super high-tech first surface mirrors are horribly expensive, and I think that buying a 1/4 wavelength, 94% - 99% reflective first surface mirror is great if you are working with lasers and require that kind of precision, but it is overkill for a DIY projector.

Sometime they are available from a surplus outlet such as:
http://www.sciplus.com/category.cfm?subsection=21&category=190
2579 MIRROR, FS, 160mm X 183mm (6.3"x 7.2")
$3.50
but that's the biggest size you can get right now.


I'm not saying use a regular second surface mirror, because the image really sucks. The first surface mirrors listed here work perfectly well for our purposes and are a lot cheaper.

http://store.allstainedglass.com/fronmirsheet.html
Two sheets of 16" x 12-1/2" high-tech aluminized Front Surface
$29.95

http://www.gwcpros.com/products/product_clarity.html
Clarity - Front Surface Mirror 8" X 12-1/2"
$11.16

http://shop.store.yahoo.com/whittemoredurgin/glassmirror.html
Front Surface Mirror 12" x 12"
$5.60

http://www.finnsglass.com.au/docs/Projects.pdf
Page 4
3MM FRONT SURFACE MIRROR - 300 X 300MM
18.00 AU

http://www.sunlightglass.com/SunlightMisc.pdf
Page 3
Front Surface Mirror /sq. ft.
$16.00

http://www.alpineglass.com/shop/product.php/id/25KFSM/
Front Surface Mirror 12-1/2"X16" sheet .048" thick
$18.00

If you just have to have the mid-range (little bit more perfect) first surface mirror, look at:

http://www.fsmirrors.com/
.12 inch thick 10" x 8"
$38.00


Hope I helped someone save some money.

T.

 

[cooldrums]

Thanks for those helpful links, just what i was looking for!

 

[Altec]

I always check SShed first. Im here in PA after all. hehe. Anyhow they have a sale on FS right now. I got two yesterday for $5. And a 4 3/4" cold mirror-$5, totall shipping $5. That good info tgreenwood. If you can find more -cold mirrors or any good priced HOT mirrors let me know. MUST be tuned to visibile light specturm though. I got ONE so far.😀

 

[jcbklyny]

I wouldn't say that high quality first surface mirrors are overkill. Just high end, and too expensive for most people looking to through this project together for $300.

For example: When you use cheap first surface mirrors in a projection system... if you look behind them you'll see light passing through or the light loss of the mirror. With an enhanced first surface mirror you don't see any light passing through the mirror and light loss is almost eliminated.


-JCB
www.diybuildergroup.com

 

[cooldrums]

What if you double them one behind the other. Does that create some sort of ghosting or weird stuff?
Your right, my goal was $300 which is obtainable, but not with mistakes. I've made my share, i'm at about $425.

Still cheaper than an X-1 but right now my quality doesn't quite match that. I have ghosting problems. I'm hoping this front surface mirror is the trick. I thought the nice thick mirror i pulled out of a rear projection TV would have been good but i'm not sure it is.

 

[jcbklyny]

I dont think doubling would help. Then all your doing is trying to reflect the stray light back through the mirror again.

I have seen stage lighting with regular first surface mirrors. They actually paint the back of the mirror a flat black to reduce this effect... so if your going to try anything... I'd try that.

By no means am I saying these are bad mirrors... quite the opposite. Even a cheap first surface mirror will blow away a rear surface mirror any day.


-JCB
www.diybuildergroup.com

 

[Altec]

Your average Rear silvered household mirror reflects around 80% light typically. The rest is refracted or absorbed by the glass. Your avg. (read cheap) First Silvered (or first surface) reflects around 90% light. The high end ones take it from there. Upwards to 99% reflectivity. Now the refracted light also creates glare. Like the sun does to water in the river. So the simple fact that the refraction is cut down alone makes FS better for pj. The 10% boost in output dont hurt either. The ONLY downside to FS mirrors is the silver is exposed more (more scratches and carefull cleaning needed) and better ones have antiglare and other coatings aswell.🙂

 

[cooldrums]

Thank you for the explaination guy's. I better understand it all now.
I can use the extra 10% that's for sure. Even with a 400 watt M.H. I'm not using it to it's full potential.