DIY Video Projector

[Myren]

i was just cruising around looking for inspiration. i got some.

dream matrix:
sgi 1600sw

man, 1600 x 1024 with a nice 350:1 contrast ratio. i'd love to try out this natively widescreen puppy. now i've got to try to convince someone to have me build it for them. i cant wait to see how nice this will look.

something weird with the interfacing though. looks like it uses laptop style lcd interface, and expects you to get an extra $400 adapter. probably more effective to get one of the high res 1600x1200 ibm flat screens.



anyways, optics work never ceases. trying to get a more complete image of version 2.0 in my head.

[Myren]

alright, last post, i promise.

my screen finally finished drying. its a bit water damaged and needs a good repaint already, but its already far better than a plain ole sheet i've been using. even this shiza backup projector i'm getting a decent image now.

also, the problem where the darks washing out seems to have alleviated itself. with half new screen, half old screen, the dark scenes wash out horribly on the old screen but turn crystal clear on the new screen. very sharp, very crisp. much better. the difference is really like night and day.

i'm going to have to rewatch and replay my collection now and once i get my new bulbs.

[John_in_Az]

OK, Fserv, and ftp up and running..send me your pics, so I can get em up and running in the chat room !

Later

[gokbektas]

Hello,

I'm a young electronics engineer from Turkey. I just wondered if there any people plan to build home made TV projectors at internet and I found this forum. Because I plan to make my own projector too...

I'm working at our national electronics and cyriptology research institute's Optoelectronics Lab. My job is designing digital
imaging systems (digital cameras), general electronics design
and software/firmware development.
I'm also in my master education. I study linear optics,lasers
microprocessors and semiconductors.

I can find most off required equipment. And I downloaded
all of 30 pages of this forum. :-) I don't have much spare time
but I'll start to work about this fantastic idea.

I think using color LCD screens with amplified homogenous
light is the most realistic idea. Is it fast enough?

And is there any working project prototype photos like
http://home.bluemarble.net/~lewellyn...prototype.html ?
I mean pictures of both projector system and image on the screen.

Regards...

[lokost]

Off-axis projection

Optics gurus,

Any clues on how to do off-axis projection? I like the short throw of the delta-20 lens and would prefer to run the projector in front of the viewers to keep the fan noise away. I believe off-axis projection will enable me to place the projector without blocking anyone's view; keystone correction will probably be accomplished with software.

[zark]

I'm going to order another LCD at the first of the month. I put some more pics that show the LOA in the box. Also I purchased another LOA. Thinking of running two.

Going by the 10% rule I should have 820 lumen with one and around 1600 lumen with two.

[Type-E]

Originally posted by zark
I'm going to order another LCD at the first of the month. I put some more pics that show the LOA in the box. Also I purchased another LOA. Thinking of running two.

Going by the 10% rule I should have 820 lumen with one and around 1600 lumen with two.

I just looked at your new pics, would putting alumimum foil around interior of box enhance the light out to through the projector lens?

[zark]

Thats one of my next tests. I'm working on two LOA's now. They seem to work pretty well so far. They'll need a small fan to keep the box cool, but it wont have to be a loud cage fan.

[Myren]

putting tin foil inside your case will cause more light to come out. unfortunately, its in no way really useful.

if you look at an overhead projector, all the light goes directly from the projection surface to the overhead optics system. with tinfoil, there would be more light coming out of the projeciton surface, but it'd be aimed in psuedo-random directions, and therefore not useful.

[zark]

I would agree if I were using an ohp or had a longer length between the LCD and the lens, but my LCD is nearly touching the lens so I shouldn't waste much light. The lens is also pretty big which makes it a little harder to fill with light. Just a thought. I'll have to try it out and report the results.