It wouldn't be practical but wouldn't it be interesting to see what we could get out of a lumenlab projector that uses the sun as a light source?

You could close off a window with a board and cut a 15 inch 4/3 window in it. Mount your lcd there and place a collector infront. You wouldn't need a collimator because the light from the sun is already collimated. I don't know if sunlight would be more powerfull then a 400 watt bulb 220 mm behind the lcd, but we could probably focus the sunlight into a very small point. (hopefully it wouldn't shatter the triplet with the concentrated heat! ) Obviously this is not usuable unless we can figure out a way to stop the rotation of the earth and the forming of clouds, but I still think it would be interesting to see what it could do with it.

It would most certainly be brighter with sunlight... For the couple of minutes that the sun is in the right place. Before and after that, it would be impossible to get the light to hit the projection lens.

Unless you have a plan to stop the Earth from spinning.

Other issues: The projector then obviously becomes weather sensitive. Also, sunlight isn't at its best when the sun is close tot he horizon, the colour temp goes down.

Gaffa tape. Its uses are endless.

DJ

hahahaha!

Yeah, tape it to the moon.

But of course, we'd all have to move to whereever the sun is shining.

mmm, about the brigness point... I meassured 40000 lux once from the the sun. It was a sunny day, well, not as sunny it coul be but sunny with no clouds...

the 400W lamp would have 3200 Candelas on average, this means 3200 lux at 1meter, so 12800 lux at 50cm and somewhere 51200 at 25cm. So the brightness difference on the sunny day, makes a huge rolle on the 400W/sunlight source comparison.

I'm not sure I see your point, rox. Are you saying sunlight isn't brighter?

i would say that only the sunyest day will have better brightenss than the 400w lamp.

Yeah but don't forget, sunlight will be perfectly collimated and we'd be able to concentrate it into a really small point.

I know of an individual that is using an old 10 foot satellite dish to track the sun and reflect the light to a point to heat water, he then uses the water to heat his house.

The light reflected off the modified dish (covered with shiny surface) is enough
to set wood on fire.

So you could focus enough light to project the light, and track the light with the dish, but you'd need to then reflect the light from that point to yur "window"


Interesting concept but I dont see it working.

To tell you the truth I'm just curious to see what these make shift lcd's are capable of.

Kinda kills the movie night thou.

moonlight projector??

Humm that makes one wonder what thermal effects will the concentrated sunlight have on the fresnels and LCD screen... total meltdown?

The sunlight alignment can be tracked to keep it at the highest available light point (by an electronic light sensitive device which controls a stepper motor), but the unfortunate down side is that the light will be available at the peak power only at the Zenith around noon so if one can watch a movie between 11 am and 1pm than that may work ok... but the intensity would vary greatly throughout the day from sunrise to sunset and will not only be affected by the weather, but also by the season change and geographical location...

Hey sunlight PJ will work best in places like in Barrow AK where in summer they reache 24h of sunlight as the sun never sets for 84 days!:P

Check this out:
http://www.alaska.com/places/cities/other_...p-4770215c.html

Well... good luck with this idea and your testing travels to Alaska!

EQUATORIAL TRACKING PLATFORMS

Oh, are you guys going to be excited to hear this-- DIY equatorial tracking platform designs are already on the web. Typically, these tracking platforms are built by DIY astronomers to permit their simple telescopes to track the stars for approx. 90 minutes at a time--long enough to watch a movie . There is almost certainly a way you could track the sun with an optical flat (mirror) to direct sunlight (or moonlight) through your projector. I've already designed and built one to use with my telescopes.

There's an equatorial platform builder's group on Yahoo Groups, or you can Google "equatorial platform" and start reading right away.

-coma