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Turn Your 15" Monitor Into 30 Cheap
John Reder writes "Here is a way to get the most out of your PC's monitor for a few bucks. This link will take you to a page that will show you how to build a Fresnel Lens Box with common easy to find items. A Fresnel Lens Box will double the size of your screen making playing things like 3D first person shooters more enjoyable!" Lots cheaper than a new monitor. Wonder what the image quality is like tho. An amusing hack if nothing else.
I've done just this - putting a letter-sized fresnel lens its focal length away from the monitor (for the lens I had, that was ~8 inches). I was able to project the image on to sheets hung across the room. It was kind of neat - I watched some display hacks on my ceiling.
* The image was backwards. This could be fixed in software, but instead I got a mirror and started projecting onto the ceiling.
* The brightness was low. Two reasons: If you make the picture twice as big, it's half as bright (assuming every single photon makes it to the right place). If you're projecting it, you need to be fairly far away to watch it without blocking the light. Secondly, not all of the light coming out of a monitor goes straight out. The bigger the lens, the more light you get...
* Fresnel lenses approximate real lenses. And for an infinately far away source (frying bugs with the sun) they work really good. However, as the angle of the light hitting the lens increases (you get farther from the center) the quality of this approximation decreases (since you're not necessarily hitting the lens part, but will now send light through the ridges). Thus the image was fuzzy around the edges (I assume that's why).
This would work a bunch better with a real lens, except that large lenses are hard to make and heavy and expensive. You could do it with a small lens, but it would be EXTREMELY dim.
Despite all these problems my fool roommate still has a setup like this in the basement. But this is the same guy who spent ~40 hours (and ruined one of my drill bits) rebuilding a crappy $10 avacado-green sofa he took apart months before.
-me
Trees can't go dancing
So do them a big favor
Pretend dancing stinks!
Actually, what you propose would actually work.
If you can get the sun in between the lens and the sidewalk, then I can believe that the pavement would indeed liquify. A millisecond later the pavement would vaporize. Just after that, the compounds would break apart into their constituent atoms. And then right after that, the hydrogens that used to be in the pavement would fuse into helium.
It would be much safer to put the fresnel lens in between the sun and the pavement, in my opinion.
If tits were wings it'd be flying around.
I know somebody that had a lens like that - he actually heated the pavement up so much that it kinda-sorta liquified. Of course, the lense was about 30" in diameter too...
Anyway... you may want to keep your monitor away from direct sunlight if you use one of these, lest you burn a hole through the tube!!!
--
Besides the whole contraption looking pretty ugly...
Fresnel lenses features concentric rings of angled plastic. The problem is that at the edge of each ring, there must be a compensating drop in the plastic.
Your RGB monitor still constructs pixels by putting red, green, and blue phosphor triads adjacent to each other. If a fresnel edge falls across these triads at an angle, you'll get uneven magnification of the given color (i.e. for a white background, you'll see red, green, and blue patterns at the fresnel edge). Put a drop of water on your screen -- same icky effect.
Not too good.
Granted, your viewable surface may now be 30 inches diagonal, but you're stuck with whatever resolution the monitor supports. Trust me, 640x480 doesn't look any better on a 21' monitor, only larger. If you really want to upsize cheaply and don't want to waste that that Fresnel lens, move the monitor closer. Same effect, even less money. Use the lens to do more constructive things; here's a few ideas you might try..
Use the lens and a mirror to test your employers fire sprinklers.
Slip the lens under the glass of your office copier. No one will able to figure out why their copies come out backwards and HUGE.
Small animals and your fresnel. 'Nuf said.
Read the fine print on your Microsoft end user license. The part about 'your soul' and 'eternal damnation' is especially interesting.
Peel the paint of your pompous neighbors new BMW. Serves him right for making your 1982 Chrysler look bad.
You can have hot coffee sans electricity.
Use it to make eight foot high shadow puppets on your roommates wall at night. Sound effects are optional, depending on the scare level of the individual involved.
Did I miss any good ones?
.sig: Now legally binding!
..and frankly, it's not a very good hack. The room has to be pitch black in order for you to be able to see an image, and the resolution is terrible. If you want a big projected image, you'll have to buy a real projector in order to get any worthwhile results.
When the first TV sets came out (back in the 30s I think) their screens were really really small. To compensate for this, some TVs came with special lens which were like 15 inches in diameter and had to be filled with water (solid glass lens this size weights and costs too much). These lens were suspended in front of the TV screen and that's how you watched TV.
Kaa
Kaa
Kaa's Law: In any sufficiently large group of people most are idiots.
Still missing 2 images, hopefully they'll be up soon.
http://users.intercomm.com/ajones/fresnel/fresnel. htm
Is another link, this one provides more links including where to buy high quality Fresnels.
Kintanon
Check out JoshJitsu.info for Brazilian Ji
Site is /.'ed, so this might be redundant...
:) A 12"x14" mirror was only a few bucks, too.
I've actually done this before (a long time ago). A mirror, a lens, a box, and an old monitor and voila! But it's not as K-RAD as you might expect.
You lose A LOT of brightness from the expansion (imagine the brightness of a 14"er spread over a 6'x6' square!), from lens impurities (it's plasitc for christs-sake!), and from 'leakage'. This last one will KILL this project. If you try this, make SURE you enclose the box and paint it with matte black paint on the inside. Turn the brightness on your monitor up FULL-BLAST (BEWARE: I'm convinced this is what killed 1024x768 on my 14" throw-away). Also, close all your windows and shut off all the lights. Ambient light will force your pupils open and you won't be able to see the screen clearly.
The lens was $3 (!) at the local surplus store. My brother tells me it can double as an asphalt melter, but I've never tried.
I use this setup to have a CTHUGA box (486 w/ DOS, no flames, please) playing constantly in my living room. It's a very entertaining thing for me and my friends when it's all fired up, and with a program like Cthugha, the slight blurring kinda works to it's advantage. (if you've never seen/heard of Cthugha, you've missed the coolest thing I've even seen on a computer: http://www.afn.org/~cthugha )
Not exactly perfect for games, but definitely a fun geek project for a weekend. If anyone has any questions, don't hesistate to email me.
Bart "We don't need no stinkin' accounts" Grantham
grant_b@cs.odu.edu
PS - Add MAME to the mix and rock on out with some Ms PacMan. Don't deny that is what computers are for!