I have some small q's about how excatly to arrange things, any pointers and answewrs are greatly appreciated.
Parts i have:
-two 15" LCDs (from monitors-gonna have to do the ribbon extension on them, or use light guide)
-2 fresnels (from OHP)
-bi-cobvex lens (01 LDX 223): check out the specs and tell me if I got the right thing for a 15"LCD, etc- http://shop.mellesgriot.com/mlgriot...9&dept_idOpt=313&dept_id=313&pf_id=01+LDX+223
-the projection lens unit from a 3M OHP- has a 45 deg mirror and two meniscus lenses (is this unit useful?)
q's:
-about the fresnel, as it was on the ohp, the rougher side faced the light source, while the almost, but not completely smooth side faced the surface. this means the smooth should face the lcd?
also regarding the fresnel, should it be placed immediately behind the lcd, or should there be some space- the lens is taller than the lcd but is exactly just as wide as the panel- will this be a problem?
-should i use all three lenses, or keep the bi-convex for a clearer image?
-should i stack both lcd's so that the contast ratio is greater?- this will require an aextremely powerful bulb imo, but may have great color- has anyone used two displays? i can easily wire for them to share a single vga/ d-sub cable.
-last thing, i used an attached Excel sheet diy projector calculator for the optics and got some surprising values: could someone download it (Excel required) and verify?
My values were as follows:
-Lens focal length: 7.88" (LCD to Lens distance calculation based on this fact)
-LCD diagonal: 15"
-LCD to Lens distance: 8.24"
-Lens to screen distance: 180"(15')
-Diagonal size of projectoed image: 328.33"! -this is pretty big, just over 26.5 feet! also, the lcd to lens distance seems kind of short. am I retarded, or this is how it should come out?
Thanks for any help! I'll keep you posted on my progress and will have some images as soon as I get started- all I need is a light source in terms of parts.
Parts i have:
-two 15" LCDs (from monitors-gonna have to do the ribbon extension on them, or use light guide)
-2 fresnels (from OHP)
-bi-cobvex lens (01 LDX 223): check out the specs and tell me if I got the right thing for a 15"LCD, etc- http://shop.mellesgriot.com/mlgriot...9&dept_idOpt=313&dept_id=313&pf_id=01+LDX+223
-the projection lens unit from a 3M OHP- has a 45 deg mirror and two meniscus lenses (is this unit useful?)
q's:
-about the fresnel, as it was on the ohp, the rougher side faced the light source, while the almost, but not completely smooth side faced the surface. this means the smooth should face the lcd?
also regarding the fresnel, should it be placed immediately behind the lcd, or should there be some space- the lens is taller than the lcd but is exactly just as wide as the panel- will this be a problem?
-should i use all three lenses, or keep the bi-convex for a clearer image?
-should i stack both lcd's so that the contast ratio is greater?- this will require an aextremely powerful bulb imo, but may have great color- has anyone used two displays? i can easily wire for them to share a single vga/ d-sub cable.
-last thing, i used an attached Excel sheet diy projector calculator for the optics and got some surprising values: could someone download it (Excel required) and verify?
My values were as follows:
-Lens focal length: 7.88" (LCD to Lens distance calculation based on this fact)
-LCD diagonal: 15"
-LCD to Lens distance: 8.24"
-Lens to screen distance: 180"(15')
-Diagonal size of projectoed image: 328.33"! -this is pretty big, just over 26.5 feet! also, the lcd to lens distance seems kind of short. am I retarded, or this is how it should come out?
Thanks for any help! I'll keep you posted on my progress and will have some images as soon as I get started- all I need is a light source in terms of parts.
Calculator in .xls (Excel)
The file is what I used to obtain the values as aformentioned.
I didn't want to zip the file, and just renamed it, so u must rename it to *.xls!
The file is what I used to obtain the values as aformentioned.
I didn't want to zip the file, and just renamed it, so u must rename it to *.xls!
I'll answer what I know. 🙂
Also, I would put the fresnel immediately next to the LCD, and use other optics to do the focusing, but if you don't have as many lenses, in order to get the image in focus you may need to move the fresnel. The closer you have the fresnel to the panel, the more light you can gather. It doesn't matter a whole lot if you put the fresnel a half an inch away, it really all matters what you want to do. Play with it and see what gives you the best image.
It shouldn't matter that the fresnel is too large, that can only help you. If you think it's getting in the way, you can trim it down to size (unless it's glass), but it really shouldn't matter.
No idea what to tell you for focal lengths, that was never my strong point. Hope this all helps you out a little bit, but I'm afraid that it didn't.
Meniscus lenses would be useful for the same thing that the OHP uses them for -- focusing lamps if that is the route you choose to take.Sweetrobot said:
It shouldn't really matter which surface faces the LCD, I would probably put the smooth side facing the LCD because you can get the lens closer that way, but it really probably doesn't matter. It's less than a millimeter difference. 🙂
Also, I would put the fresnel immediately next to the LCD, and use other optics to do the focusing, but if you don't have as many lenses, in order to get the image in focus you may need to move the fresnel. The closer you have the fresnel to the panel, the more light you can gather. It doesn't matter a whole lot if you put the fresnel a half an inch away, it really all matters what you want to do. Play with it and see what gives you the best image.
It shouldn't matter that the fresnel is too large, that can only help you. If you think it's getting in the way, you can trim it down to size (unless it's glass), but it really shouldn't matter.
Again, I would just prototype it and see what works. Don't build your whole projector at once, use Legos if you have to just prototype positions, and then build it how you want it afterwards.
Well, if you stack the LCD's, you wouldn't as much light loss as you might think because light going through the second panel will already be polarized. However, I'm not sure if it would give you greater contrast, it may only give you more dimness. Someone else should answer this one, I just wanted to say the polarization comment.
No idea what to tell you for focal lengths, that was never my strong point. Hope this all helps you out a little bit, but I'm afraid that it didn't.
Sweetrobot said:
I personally would reccomend against trying to use two panels on one projector. To make this even possible they would have to be aligned perfectly or the image would be spread around and look weird. Even if they were aligned have you ever tried focusing two things an on overhead at once? because of height from stacking them the other one will be out of focus. Also your biggest issue is light. It has been said by some that a panel outputs about 10% lumens that are put into it. You are then taking that already weak light and reducing it down. So in short two panels stacked will not work.
Thanks a bunch! HanClinto, thanks especially about the polarizing comment. As for the LCD stacking, I am certain that it will in fact provide greater difference, and aligning would be quite easy- each display is of the exact same size - 15", and the same company, though different models- all the specs are the same. There would be no space between the lcd's since these were extracted from actual monitors, and are bare-bones- only the glass oanes entrapping the suspended crystals. As for the optics, playing around will be the best, so your suggestion to prototype is the best. I was planning on testing first, ofcourse, but really wanted to know whether I should use the bi-convex in conjunction with the meniscus lenses to imitate more like a real projection system works- one for projecting, while the other focuses, or enlarges the projected image- optics is admittedly a wekpoint of mine. I realize I'm gonna have to do some more research in that field.
For the time being, is there anyone out htere using more than a bi-convex to project the image? Any input on setup/ results is greatly anticipated. Thanks for your replies HanClinto and Mario 007!
I added this 2 lens setup. give it the same treatment as the above file- rename .zip to .xls - need MS Works to read.
For the time being, is there anyone out htere using more than a bi-convex to project the image? Any input on setup/ results is greatly anticipated. Thanks for your replies HanClinto and Mario 007!
I added this 2 lens setup. give it the same treatment as the above file- rename .zip to .xls - need MS Works to read.
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