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Rear surface mirror any good?

jaycey

jaycey

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Im putting together a spiro and only have a sheet of acrylic rear surface mirror, the shaft of my motors is only 1mm.

Do you think it will still be ok or will the shaft showing mess my beam/image up?

Jason
 





jaycey

jaycey

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OK, I thought my problem would come from the shaft being visible from the front.
Didnt think about the reflections...derr!

Ile give them a try as I have them and get some FS mirrors as well.

Cheers
 
daguin

daguin

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Rear surface mirrors will give you a "shadow" projection. You will get one reflection off of the rear, mirrored surface and one weaker reflection off of the front surface of the glass. As you can imagine, this is NOT a good idea if you want the projection to be "clean."

Peace,
dave
 
Benm

Benm

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Indeed, reflectivity of back silvered mirrors isnt really a big problem for an application like this, but you will get a sort of double-image projection. Same thing that produces 2 dots when you shine a pointer at a (bathroom) mirror. Somtimes the light also bounces a couple of times between the mirror and front surface, producing a row of dots - depends on the angle and thickness of the glass.
 
Hemlock_Mike

Hemlock_Mike

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As stated, use first surface mirrors. I've heard of some people removing the coating on the rear of a mirror and finding a good FS mirror.
Also --- Keep the mirror as light (massless) as possible. They can move faster and with less overshoot.

Mike
 
jaycey

jaycey

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What your saying has jogged my memory Mike, cant remember where it was but I too have read about removing the first coat on the back of a mirror...ile experiment with some 'substances' :)

I wont have to look at any shafts eh Bobhaha!
 
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