ok i know that the first thing that everyone is thinking is with 3 mirrors there will be a lot of light loss.

well this is what im thinking. im pretty sure the mirors are about 94% reflective. so 3 mirrors would be 18% light loss.

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1. Im using a 1000w setup.
2. By the time im finishing this projector there should be some kind of reflector done.
3. My lcd has 12.3% transmissity.
4. Im using a 18" lens which already makes image brighter.
5. I might be able to purchase fs mirror that is more than 94% (hopefully)
6. Im currently using 317mm fresnel this will be upgraded to 330mm fresnel



hopefully these factor will keep my image bright. Im probably going to purchase the wood for this projector this weekend or next weekend.

Aha - this is what you meant about taking that double-fold pic and modifying it. Ambitious! Good luck.

lol, i just read the post you ripped the image from. so what is the size of the box going to be?

With all those mirrors the image will be flipped so many times all the actors are going to come out dizzy!!!

Only light that hits the rear mirror should end up at the rear fresnel.
You'll need to put in some type of aperture stop starting somewhere
to right of label A1 extending to the LCD.

Sounds like you should consult samuraijack for a lightgate design.

Is there any scattering effect at all to worry about with so many mirrors or are they very, very planar and "clean" as far as that is concerned?

In fact, are FS mirrors manufactured to tighter tolerances than window glass in terms of their flatness? Are they some optical quality sheet? I seem to recall that glass is actually floated on a vat of mercury or something insane like that while it is cooling?

wait why is that. are u sure about that.

in a regular style projector all of the light hits the rear fresnel and it collects it.

i dont really see why i would all have to go straight to the mirror. i know that the main light will go to the mirror. but the scattered light will go to the fresnel

Take a look at the picture here:

http://www.lumenlab.com/protectedwiki/Iden...t_and_The_Image

Note that all light from the lamp is within a V shaped area between the two thin blue lines.
The introduction of a mirror just makes it slighty more complicated, but the V shaped area
should stay the same.

I don't understand what you mean by scattered light.

I believe paladin is trying to point out that any light not emanating from the arc and falling within the pyramid of light the rear fresnel would normally "see" in a design NOT FOLDED between the arc and rear fresnel may very well be detrimental to a design using a fold between the arc and rear fresnel. Check the blue rays in this pic:

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An aperature would eliminate these blue rays.

Well done Durachko!!

its either going to be one of these two. or im going to just go hass style again. lol

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does anyone see anything wrong with these. (other than the bad drawing)

I suspect the one above (the newer of the two drawings) will simply be more friendly in terms of component placement.

um are u talking about the top picture. if so that is the one i think is going to work the best.

the hardest part is that now the focal length seems really really short

Yeah - the one with the ballast shown in the upper right hand corner. Just looks friendlier to me.

it look like the box will be something like 20"x 21"

Its a bit better than that you loose 6% of the light on each bounce not 6% of the total

i.e. its not 6% + 6% + 6% = 18%
its is 94% * 94% * 94% = 83.05% efficency or 16.95% loss

oh ok i didnt know that is how it went

ok i dont think this projector has enough room to make it a tri fold so im only gonnna use two mirrors

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its going to have to be something like 23" long.

the with will need to be enough for a 13" fresnel and the ballast so im thinking somethinglike 18" or 19"

hmm, i was wondering what you were going to do with my design.... i ended up giving up on it for now and going for a haas style, i might actually do the double-fold later when i have more free time....good luck

well this should be something of how my projector is going to look.

Click to view attachment

probably something more like this
\
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As long as the box does not cut off your picture. The advantage of this design is that you can swivel the top mirror 360 degrees (if you choose to do so) and point your image in any direction. Which would make placing the projector in the room much easier, in my opinion.

You could even make it a vertical by adding another mirror after the second in the light path!

Nick

Hey I'm new to the whole DIY community, however, as soon as I save up enough money, I plan to experiment with light sources, pj designs, etc.

This idea sounds really kool. If it works, it would allow for a small projector design, (in length i mean). Anyway good luck with this, hope you the best.


-Squ33

Well, not exactly. If you were to rotate that top mirror you would need to rotate the LCD aswell. If you rotate the mirror 90 degrees from the standard, you'll project an image on it's side - 180 degrees and it will be upside down. Some OHPs have a rotatable top mirror, but the optics nonetheless require you to rotate the transparency along with the mirror.

How has this pj progressed? Any updates?

One thing I like about the concept is that the 2nd mirror is outside the box. I've thought about this, but I haven't seen anyone do this yet in the forum. I would only caution you, that if the mirror is too close to the triplet, that a double image (ghost image) could appear, making your picture seem blurry.

If this happens, it is because the mirror is not flat enough, as the projected image will be concentrated on a too small of an area. When the image is reflected up onto the wall, the waviness of the the mirror will also be reflected and enlarged. The best way to remedy would be to move the mirror out. Yes, the mirror would need to be bigger, but 's waviness will be less noticeable, if at all.

Cheers,

Fulcrum

i like the design but would leave the second mirror as the design could be moved on end, but you'd have to rotate the lcd