Lens to make sun light on a same spot
AndreiRS, Thu Mar 22 2018, 03:29PMHi. I have been observing some curious stuff in some trees here. The branches which take sun all day, "pop" a lot of new branches. So I was thinking about some shape of lens that would make the sun light hit always a same spot on the tree during almost all day. But then I remembered that concentrating light this way, I will just make the tree light up like a torch. I think I need a lens that gets light from various directions and make it come strait from the other side. But without focusing it too much. Just a little more intense than normal sun light.
Re: Lens to make sun light on a same spot
the_anomaly, Thu Mar 22 2018, 04:35PM
Sounds like you would want to collimate light? Two possibilities would be a Fresnel lens or a parabolic reflector..
the_anomaly, Thu Mar 22 2018, 04:35PM
Sounds like you would want to collimate light? Two possibilities would be a Fresnel lens or a parabolic reflector..
Re: Lens to make sun light on a same spot
AndreiRS, Thu Mar 22 2018, 05:06PM
That is what I need. Well the sun is too far, so I can't use the second option. But I have seen people using fresnel lenses to burn things or to cook food. Maybe if I turn the lens around? I'm not sure if if would work the same way on both sides since I don't have one here to test. Thanks for the help.
AndreiRS, Thu Mar 22 2018, 05:06PM
That is what I need. Well the sun is too far, so I can't use the second option. But I have seen people using fresnel lenses to burn things or to cook food. Maybe if I turn the lens around? I'm not sure if if would work the same way on both sides since I don't have one here to test. Thanks for the help.
Re: Lens to make sun light on a same spot
Hazmatt_(The Underdog), Fri Mar 23 2018, 01:48AM
Andre... all you need is some clear plastic like 20 mil thick and a hoop and some kind of stand.
All you do is attach the plastic sheet to the hoop loosely and put it up on a stand. Then you fill the plastic with water and adjust for how much magnification you want, then use a large flat mirror to direct the light.
When you get bored with that, you can use the "lens" to burn stuff, just remember to wear shades or you'll go blind.
Hazmatt_(The Underdog), Fri Mar 23 2018, 01:48AM
Andre... all you need is some clear plastic like 20 mil thick and a hoop and some kind of stand.
All you do is attach the plastic sheet to the hoop loosely and put it up on a stand. Then you fill the plastic with water and adjust for how much magnification you want, then use a large flat mirror to direct the light.
When you get bored with that, you can use the "lens" to burn stuff, just remember to wear shades or you'll go blind.
Re: Lens to make sun light on a same spot
AndreiRS, Fri Mar 23 2018, 04:48AM
Hmmmm, I saw that in these survivor programs on TV. I will try to build one. Oh I did some burning already when I was a kid, but never wore the shades.
I will make a little one and then I come back here if it works. 5cm or 2 inches in diameter. Thank you.
AndreiRS, Fri Mar 23 2018, 04:48AM
Hmmmm, I saw that in these survivor programs on TV. I will try to build one. Oh I did some burning already when I was a kid, but never wore the shades.
I will make a little one and then I come back here if it works. 5cm or 2 inches in diameter. Thank you.
Re: Lens to make sun light on a same spot
Conundrum, Fri Mar 23 2018, 10:02AM
Interesting hypothesis.
Some combination of mirrors and Fresnel lenses might work.
Conundrum, Fri Mar 23 2018, 10:02AM
Interesting hypothesis.
Some combination of mirrors and Fresnel lenses might work.
Re: Lens to make sun light on a same spot
Sulaiman, Fri Mar 23 2018, 11:26AM
Sulaiman, Fri Mar 23 2018, 11:26AM
Re: Lens to make sun light on a same spot
AndreiRS, Sat Mar 24 2018, 12:18AM
Hi Conundrum, I just realised I can't find any of these around here to buy. I will try first with some cheap magnifying glass and also the water lens. If it works I may buy something on the internet.
Thanks Sulaiman, maybe I can put together something like that. I only need to measure some angles, or just get a mirror, go there and try.
AndreiRS, Sat Mar 24 2018, 12:18AM
Hi Conundrum, I just realised I can't find any of these around here to buy. I will try first with some cheap magnifying glass and also the water lens. If it works I may buy something on the internet.
Thanks Sulaiman, maybe I can put together something like that. I only need to measure some angles, or just get a mirror, go there and try.
Re: Lens to make sun light on a same spot
Sulaiman, Sat Mar 24 2018, 11:10AM
I guess that building a heliostat is a major project in itself.
You could try a static mirror arranged to sweep the bright spot across the foliage as the day progresses.
A large mirror should provide the equivalent of maybe 1 hour extra sunlight per day.
If this is significant then a band of different growth should be seen where the spot travelled each day.
Or just hang a sheet of Al cooking foil behind a test leaf/twig/branch for double sunlight ?
Sulaiman, Sat Mar 24 2018, 11:10AM
I guess that building a heliostat is a major project in itself.
You could try a static mirror arranged to sweep the bright spot across the foliage as the day progresses.
A large mirror should provide the equivalent of maybe 1 hour extra sunlight per day.
If this is significant then a band of different growth should be seen where the spot travelled each day.
Or just hang a sheet of Al cooking foil behind a test leaf/twig/branch for double sunlight ?
Re: Lens to make sun light on a same spot
Conundrum, Sat Mar 24 2018, 03:57PM
Maybe a CR servomotor or one beefed up using a larger motor, gearbox (hint: swipe one from an old school stereo with the motorized tuners) and the original trimpot. For this application high speed is not required.
Also relevant, use a simple magnet and 4 pin linear Hall sensor from a defunct VCR or floppy drive motor assembly
Conundrum, Sat Mar 24 2018, 03:57PM
Maybe a CR servomotor or one beefed up using a larger motor, gearbox (hint: swipe one from an old school stereo with the motorized tuners) and the original trimpot. For this application high speed is not required.
Also relevant, use a simple magnet and 4 pin linear Hall sensor from a defunct VCR or floppy drive motor assembly
Re: Lens to make sun light on a same spot
the_anomaly, Sat Mar 24 2018, 04:27PM
If you get a moderately powerful >300W xenon arc lamp and build a parabolic reflector, you could just shine it at the tree. Probably more expensive and a bit more dangerous due to the tremendous heat generated.
Some arc lamps like this lamp have a reflector built in. The two types used are parabolic and elliptical. You could collimate the elliptical to get the beam you want.
There are a lot of spectrum grow lamps as well that you could look into.
the_anomaly, Sat Mar 24 2018, 04:27PM
If you get a moderately powerful >300W xenon arc lamp and build a parabolic reflector, you could just shine it at the tree. Probably more expensive and a bit more dangerous due to the tremendous heat generated.
Some arc lamps like this lamp have a reflector built in. The two types used are parabolic and elliptical. You could collimate the elliptical to get the beam you want.
There are a lot of spectrum grow lamps as well that you could look into.
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