Apr
12
Fresnel Lens Focal Length Change With Water, Concentrated Solar Power
By
This is a raw unedited video in realtime demonstrating the physics of light through a Huger Fresnel Lens. As water is added to the Fresnel side of the lens, the Focal Length triples due to water filling in the grooves of the lens. The optical quality is reduced causing the light to spread over a larger area. The overall energy concentrated is the same (less water filtering). This solar Fresnel Lens with a 40″ focal length increased to almost 9 feet or 108″
Twitter
Facebook
25 Comments
April 12th, 2010 at 10:09 am
Thanks for the safety tip, Dan. Anything else we need to know about? =^[.]~=
April 12th, 2010 at 10:21 am
If we every get wind here in FL I will test your turbine design. Looks really good, I just need wind.
Dan
April 12th, 2010 at 10:51 am
hEY DAN, I LOVE THE ONE I GOT FROM YOU. IT HAS ENTERTAINED ME WELL. I HAVE COOKED HOTDOGS ON IT AND MADE COFFEE AND I TRIED TO COOK SOME FISH BUT I REALLY FRIED IT .
I MADE A COVER FOR MINE AND A PRETTY GOOD STAND. ITS NOT AS PRETTY AS THE FRAME YOU MADE BUT ITS STURDY. AND ADJUSTABLE. I TRIED THE WATER THING AND GOT RESULTS OF ABOUT SEVEN FOOT. IT RUNS MY ENGINE REAL GOOD. THANKS
MUDDy
April 12th, 2010 at 10:55 am
@koenstr Correct me if I’m wrong,I don’t know about a Fresnel Lens but for a normal convergent lense the thicker it is the smaller the focal length is. Water works as part of the lense’s thickness.
April 12th, 2010 at 11:00 am
but the question is: why is the focal length increasing???
April 12th, 2010 at 11:33 am
Is there any kind of laquer or some other liquid that would harden with nice optical qualities to permanently increase your focal length?
April 12th, 2010 at 12:17 pm
nice tip
April 12th, 2010 at 1:16 pm
I learned something:-)
Norway
April 12th, 2010 at 1:49 pm
Amazing tool!
April 12th, 2010 at 2:18 pm
Another great video, I love our beloved Sol……
Oh & I enjoy Dan to!
PS:where is your wife lately?
April 12th, 2010 at 2:58 pm
Very interesting! Of course, you could always have a thing plastic or glass protector to keep water off the lens–without losing TOO much light.
I suppose the water collects in the ridges, which would HUGELY change the parameters of the lens.
April 12th, 2010 at 3:37 pm
Cool
April 12th, 2010 at 4:21 pm
that was your most nauseating video yet, but It still got 5 stars from me.
Dan Rojas is so tough, he eats still wool for breakfast.
April 12th, 2010 at 4:39 pm
Wouldn’t it be easier to have the groove side facing downwards? Or is the lens grooved on both sides.
Ok, I know they’re not grooves, but I don’t know what they’re called.
April 12th, 2010 at 5:09 pm
squirrelbong :
Is caused by the refraction variation caused by the water filling the grooves
of the Fresnel surface (i think).
April 12th, 2010 at 5:36 pm
Oooooo. Dan is smoking grass.
April 12th, 2010 at 6:02 pm
I bet the Florida Dew might of killed some of them poor ants on the ground around you
April 12th, 2010 at 6:43 pm
awesome
April 12th, 2010 at 6:52 pm
great video, is this effect caused by the water’s surface or the temperature change from the water?
April 12th, 2010 at 7:31 pm
Ususally I use a BBQ or open fire for charcol making, but I think the fresnel would be better as I’m sure the beam would be hotter than most BBQ’s and definetly more effecient, plus no open flame!
April 12th, 2010 at 7:55 pm
Wow! I had no idea the focal length would change like that with water. Also, you just gave me a very good idea. I often make my own homemade charcol for black powder, filters, ect…a Fresnel would be perfect for that. Just get a quart paint can, (clean) and fill it with pine or light wood with a very small hole in the lid,….and in a small time…30 mins or less you’d have a can full of high quality charcol! Now I know I need a fresne.!!!
April 12th, 2010 at 8:45 pm
Awesome as always
April 12th, 2010 at 9:04 pm
I didn’t realize that about Fresnel lenses. Thanks for the demonstration.
April 12th, 2010 at 9:13 pm
FIRST
April 12th, 2010 at 9:39 pm
cool