Inserted below is a questionable mod at what angle would the 3rd mirror have to be placed to make this picture true? I hope that this does not affend you Brain that I used your design as an example

I believe that the mirror was intended to be hinged so that you could direct the image to where you wanted it.

Also I believe that this plan is only prototypical.

Thanks, I do know that it is only a prototypical design but it has sparked my curiosity as it has many others before me I will be trying this design as a 7" shrinking the specs a bit, but I will shift the 3rd mirror to the inside and oposite the objective lens if in fact just a prototype I hope that I can take from this idea and tweak it a bit more.

I don't believe that you can move the hinged lens to the inside, before the projection lens.

If you do, then the angle will have to be such that it directs the projected image to the center of the projection lens with an appropriate focal distance. This will naturally depend on your placement of the projection lens.

I meant like this

This doesn't look right to me mirror so close to LCD seems difficult to get working well and the last mirror seems to be at the image invesion point, that that this couldn't work but passing all your light through one point seems risky any minor defects (nothing is perfect) and your image is toast.

your projection lens has to be placed at the fov of the fresnels, your lens is about 6" to far away.

These plans look very promising for a 15 inch project but has anyone made a 15 inch projector using these plans? And if so where can i go to see the results?


Thanks
Q.

I guess the ball is in the experimenters hands I will try this setup but I am in the middle of moving soon my friend soon

i drew it up and built it, and also using it inside the LL RPTV. you can see screen shots just search my name.

Joe

Looking at the first plan shown in the first post, could I reduce the height by having the light source reflect off of the mirror at a 60 degree or even 30 degree angle, and then angle the LCD and freshnels even more? I hope this makes sense .

i've seen this drawing around a few times and i'm really interested in using this design for my build. for anyone who's either constructed it or just has lots of knowledge, what distances should i use between the LCD and fesnels and does anyone have any exact mesurements for the placement of the bulb and/or the light shield?

Simp1yamzn,

Your questions are beginning questions, so please reference the "Lumen Lab Basic Projector Guide" and down load the file, and also visit the "Beginner's Forum" as well. There is much information available with excellent explanations.

As far as the fresnel distances to the LCD, the measurement isn't any different for this Folded PJ with 3 mirrors, than it would be for a typical straight design (no mirrors). The rule of thumb is 1/2 inch (12.7 mm). Yes you can increase and decrease this gap, as several LL members have, but a 1/2 inch is adequate.

Please note, that for the fresnel between the LCD and bulb, the gap should never be too big, as you should have an outside air vent, next to one edge of the LCD that allows air to a stream between these two panels (LCD & Fresnel). If the gap is too big, the air will slow, and the LCD may not be cooled quickly enough.

The purposes of the light shield is too eliminate a double image from occuring on your screen. For every light source/path there is a potential for an image. So when a mirror is added a new light path is created. Therefore the wall should be long enough to keep the undesired path from entering the fresnel. However, I do not have the exact distance. It appears it may be a trial & error location, as 3 paths must be determined.

Cheers!

Fulcrum