DIY Video Projector

[fender4]

Here is the "laser projector" thread:

Laser projector

Started by remp! Very interesting read. I wonder how close that is to mountain_nz's design? This could really shake things up if it works out.

Good luck everyone.

-f4

[Gunawan W]

I have a problem with refraction.
It's cause projected image on the screen can't get sharp enough, for example: when I projecting black line to the screen, there was blue and red line following on each side of the black line.
All I know it's because of single lens I use, the lens will bend light spectrum with different angle.
To elliminate this, we should use more than one lens with different refraction index (is this what we call doublet, triplet or multi achromat lens?).
The question is, how to choose correct lenses so the final result is sharp projected image. (maybe it will need some calculation, but can't find the formula).
I would like to know, is this problem also happen in OHP lens?
Undream and Fender4, since your setup use single plano-convex lens, did you have the same problem as I had?

Waiting for help.

[Xdreamer]

Hi marklar,
thanx for the info...and myren what kind of a screen were you talking about in avsforum ?
Would like to know more..and if anyone is interested the XBO short arc xenon bulb produces
6500K color temp and a CRI of >95 ...but the down side is lifetime of the bulb is short...

ps: mountain-nz , would like to hear fr u as well
kool idea...hope its worth while

[aggrojosh]

hey,

i'm goin to be taking on this project soon here...
but first some questions...

Whats a fresnel lens?
would the lens out of a projection tv work?
Ive seen some projects with a 5" lcd and a a lot smaller lens.. does that still work if the lcd is bigger than the lens?

Thanks Guys....
-Josh

[Xdreamer]

Hi mountain_nz:

What is the main advantage of using laser projector? You mentioned using a 60'X40' screen but don't you think the light output from the led would be to low to achieve an exceptable image?

and what about resolution? What kind of resolution can you expect from a laser projector? UXGA? QXGA?
i have just purchased a 21" UXGA lcd panel for my lcd based pj...pls tell me that i did not waste $2,700...but if the laser projector can produce a better image quality..then count me in..
would love to hear about it?

my estimated budget was $8,000 ...

[theArchGu]

Does anyone have opinions on Florescent lights? I would like to start on this project, but I'm not sure on which lights I want to use for this project.

Thanks!

[tomithy83]

floresent baadd

point source good

try metal halide(mh), murcery vapor(mv), or plain halogen lights
watch out on halogen they get hot and can melt the lcd

[tomithy83]

i'm sorry i didnt explain why flo lights are bad

the light from the bulb spreads out from many points and striks the lcd @ many different angles bluring the image

[Scot_lad]

I still reckon a point light source is only use if you're using a fresnel. I think if you use a bigger light source with some kind of polarizer you could be fine.

Commercial LCDs don't come with point light sources do they? And they've got the best image of all - if you could get that quality on the wall you would be happy.

I read recently about some company (forget who) managing to create a thin and flexible LCD which is very cheap to make. It is almost as easy as printing onto paper. Look out for giant cheap LCDs in the future.

But this will be years in the future and just how "cheap" they will be remains to be seen. I wouldn't buy one anyway. I bet people who bought plasma screens for upwards of £17k will be pissed off now they're available less than half of that.

[Xdreamer]

Scot_lad,
I think the commercial lcds do use point source lights like the UHP lamps thats the reason that they have high uniformity ratio...using dispersed light source is ok but you will only utilize like 25% of the light source so it is unadvisable...