Okay, I got tired of waiting for "someone else" to do it, so I took Joe's folded 15" drawing, and modified it for the pro-lens kit. This is my MS Paint hack-job of Joe's awesome cad design, so I apologize for the quality. I plan to clean it up some more, but I though some of you might like to see it.

Of note, the measurements should be correct, (although I wouldn't mind someone gonig over it, if they wanted) but the drawing might be slightly off scale, as I was eyeballing it...

Here's another, this one is set a little taller:

Remember, both of these designs were creat using Joe's design and working backwards using the focal lengths of the new Pro Lens Kit. These are just my rough drawings made in MS Paint today while I was bored. They are not officially endorsed by Lumenlab, nor do I accept responsibility for the accuracy of the measurements. I encourage you to double check my math before busting out the Skill Saw...

hey good work, i can see if i can take them and verify the diminsions, but may take a day or two.

Thanks! I really didn't do much but cut-n-past your CAD drawing (and a little math...)



That would be great, thank you! If you do notice something, edit this post as you wish...

Ok, since we're posting ideas... How about a zoom tower? No it's not real compact, but if you get an upright design tall enough you will need little or no keystoning.

Maybe it will look nice between those rear surround tower speakers.

Not to scale. Might be a little tricky to cool.

The one I built is similar to that, but I made the mirror/lens part moveable, I didn't want to deal with the electronics moving up and down.

If we are folding for space why not try something along these lines? I think that it might increase the stray light bouncing through the area around the lens but that should be fine because it wouldn't be traveling in the right direction to make much of a difference to the projected image. The tricky part would be mirror placement, those aren't easy angles...

Or... these, this way you could have the lens at a normal (90degree) angle with the box. both of them are approximately the same as far as footprint. The one with three mirrors gives you a little more focus leeway. I recently finished my first projector and was surprised at how far towards the lcd I had to put my lens. I didn't know that the focus of the field lens was actually past the triplet. Anyway. Whaddya think? I guess these don't really belong in the "simple folded" section but I didn't think they warented a new section at least not until I've done the math on angles and such. The blue lines are fs mirrors and the green represents collector, LCD and field lens. They are roughly to scale using a 15" lcd (~12" in the long direction).

Neat stuff. In your first two designs you have the light path crossing itself which is bad due to interference. In my folded design the panel actually sits in the box at a 45º angle vertically, to get the height dimension down. (Talk about some hard angles on the mirrors).

Oh so you're talking about folding the light in 3 dimensions rather than these 2D drawings is that right? that would utilize the space better but doing the geometry ... blech. So do you really think that sending the lightpath through itself would really cause that much interference? I mean you are already doing that to some degree with the single mirror upright design. Also what kind of losses are we talking about with fs mirrors? Is it negligible? or do they absorb too much energy. That is, if I could save space by folding three times versus taking up more space with two folds would there be much difference in image quality/brightness? Lot of questions there I know, if you've got the time.

Yep 3 dimensions. The last mirror in my 3 mirror design has a compound angle. Intuitively I don't like sending the path through itself, but these designs are new and might prove to be fine. Certainly more experimentation is needed. With FS mirror you're going to take a 6-8% loss per mirror. This can be compensated for with a smaller lamp and better designed light engine.

That really sounds like the way to go for maximizing space. The tricky bit will be to see if it can be done relatively easily. The more mirrors you have, the more each angles precision will be important. I thought about building a test box such that everything after the field lens is nonexistant *except maybe a baseboard* so I can move the mirrors around all I want and play with placement and angles of mirrors and triplet

The basic design of the simple projector is probably going to be quite large using the pro lens kit, so a folded design like the first one of these is interesting. But I wonder, will placing the lightbulb below the lcd panel cause heating issue?? All the hot air will then rise towards the lcd panel. This design would also be interesting in a horizontal version. Then the hot air would rise towards the top of the box instead of towards the lcd panel. Would this be possible just by turning the lcd panel 90 degrees if the first drawing was representing the top view of the projector?


The Edge

I suspect the drawing fails to show the required tempered glass between the lamp and the collimator fresnel. This would provide the necessary thermal isolation.

Agreed!

No, this won't be a problem. Interference is a 100% local phenomenon - "downstream" of the crossing/interference, the light beam will be exactly the same as if there was no crossing at all.

NOTE that this ignores the very rare and esoteric phenomenon of photon-photon collisions, which would result in a bit of scattering in the case of the folded light path. This effect is barely measurable in the context of quantum/particle/photonics experiments, and can be safely ignored in our context.

Hope this helps,
Phil.

Yeah those drawings were meant to be rough estimates of the layout of the box. No details are included (ballast electronics and such) The angles that the light makes exiting the fresnel are drawn to scale only if you consider this a "top view" for a 15" LCD panel where the length of the LCD and fresnel enclosure is 12" across.

I would be interested in a 15" folded design to accomodate an in-ceiling projector that would allow the Pro lense and mirror to actually pull down from the ceiling plane after the LCD and before the reflecting mirror. Would the angles of reflection be the same as long as the trap door portion would swing to the 45 degrees? Thanks for any insight. JC

Here's an idea that's similar to what you describe, the lines inside the box are supposed to be the light path (ignore for the closed configuration) The hinge would be at the left most portion of the swivel section. The stationary section would be completely enclosed except for where it joins the swivel section, the swivel section would have to have a gap (indicated by green line) in the top of it in order to clear the stationary section when opening/closing. This would have to be filled or covered with some sort of flap. or hinged panel in order to seal the box (to contain the light) when in the open position. The idea is that the swivel section is slightly bigger than the stationary section and could pivot on a rod connecting the two and slides over top of the stationary section. The gap problem could only really be avoided if you make the stationary part have a circular curve to it, (which would be difficult unless you have good shop skills or equipment).

Fantastic

Thanks Picklejones. I was actually thinking more on the line of using Joe2000chevy's vertical design (thanks Joe) and doing something like suggested by the red lines (I hope it was OK to edit) and of course using a side view as opposed to the top view here. I hope you get my drift. This way, when the projector was not in use I could fold it up into the ceiling out of view and pull down the mirror and triplet when I wish to view. What you think. JC

I was thinking about using Joe's design as well. Does anyone know how large the FS mirror would have to be for a 15" LCD? I am having trouble locating a FS mirror larger than 8"x8" for a reasonable price. Would 8"x8" be large enough? and if not does anyone have suggestions on where to buy mirrors? Thanks.

I have the mirror 12 x 16 for $29. If you need one write to sales@lumenlab.com

another option using this box design that i think may have a higher WAF is if instead of hinging the lower section for it to swivel, how about if it just lowered and raised up 'into' the upper portion of the box??????
My thought is that, in your pic that shows it in its projecting form, you could have a piece of 'ceiling' attached to the bottom of it, and there would be no light leak if built right. make the lower section 'just' wider(or thinner) than the upper part, and have the hole in the ceiling just larger than the lower part, that way, when you close the PJ up, the lower part can rise right up into the upper box, the mirrors will miss eachother, and then the part of ceiling taht is on the bottom plate will cover the hole in the ceiling, making it almost seamless - lowering it could be done MANY diff ways, even electronic, if you wanted

My idea based on your idea - man, i LOVE these forums

muuuhhhahahahahaha

man that setup would be super sweet! Imagine lowering it with a remote. you'd have to make sure that the lcd is still getting cool air. since it's pinched in a small area, wouldn't want the exaust from the fans getting back into the intake.

well, if you mean, AFTER you're done watching, you could make a realy to raise it only after the temps are low enuf - FUN
BUT, if you mean while watching, it would be the same as your original design, and nothing after the LCD should effect the temps anyway
if I was going into an attic, this is what i would do for sure, now, only to convince the wife.........

Oh, maybe I don't understand exactly what you want to do. I was thinking that you'd have the entire projector in the ceiling (invisible) and when you wanted to watch, you'd pull down a section of the ceiling. If that was the case then I thought the exaust system and intake would both be in the ceiling. If the projector was sitting in between floors, then the space it's heating (by exaust) would be small and it could affect the intake as well if the intake was also in the ceiling. But I guess you could just cut a slot in the ceiling for the intake and have it on the bottom of the projector instead.

attic or between floors - big difference in space and cooling...............

i was thinking attic

The focal length of these drawings seems to be quite a bit too long. Wouldn't a different fresnel be required to have this long focal length?

EDIT: OK, I can see these drawings are based on the "Pro" lens kit. Which appears to have a much longer focal length. What exactly IS the focal length of the Pro kit? 790mm? Thanks

It's going to be 650 with a placement of 572
John

I don't have CAD to make any accurate drawings or anything, but what about a simple 2 - 45° mirror design that reflected the image back.

Rough estimate dimensions of this box would be something like 32" deep, 18" tall and 24" wide.

I know it's bigger than the drawings made by Picklejones, but is "much" simpler. I don't know if I could build one of those with all the funcky angled mirrors.

Agent,

I was running with that setup on paper for a long time. It's possible with a 15 inich panel or smaller. To visualize it better, make the whole thing out of construction paper or poster board and fold the cones. Folding paper is the same as drawing without the math. From the bulb to the lens. You can fold and get two 45's in there but it is very tight where the FFC's are. You also have about 1.5 inches of adjustment. I ultimately decided against it due to two mirror reflection losses and a change to a 17 inch panel.

John

Can anyone add measurements to PickleJones's diagram on the previous page? The one that would be a ceiling mount with folding triplet section. I like this design, even if it did not get folded up into the ceiling. I am wondering about the measurements. I have limited space in my basement ceiling because the floor trusses run the wrong direction of my theater.

Thanks,
CMessa

Have any of you tried to make a vertical design with the mirror at the top, and where the top could be rotated 90 degrees so that the projector could either stand on end or lay on its side on say a bookshelf? it seems to me that many of the designs for the 17" vert are almost square ~16" X 17" and therefore if it were just made square and all ofthe components centered, one could enhance the flexibility of positioning greatly as well as eliminate the issues with keystoneing and hiding the huge projector. Just trying to bounce around an idea here, I think that i will be trying to do this so i will keep you all posted.

http://sol.sci.uop.edu/~jfalward/lightinte...terference.html

johnjohn,


do you happen to have the autocad file? i would like to modify it some if you do...

I was wondering if i used a mirror in my build, could i use it both as a vertical and horizontal pj. I know there are some settings on your video card that allow you to rotate your screen. It seems like this would work. Let me see what you think about this

very nice but i have a question. does sombody have some drawings er mesures for a 15.4"

As long as your using the same optics it is the same

thx mate

when i click on the attached images, i get this:
"Sorry, but you do not have permission to use this feature. If you are not logged in, you may do so using the form below if available." any thoughts? thanks.