The rotation speed is inverse to the square root of the desired focal length. rotation speed is sqrt( g/ (2*F) ) / (2*pi) where g is gravity (9.81 m/s2), F is the focal length in meters, and the result is in rotations per second. The rotation shown - about 1 rotation per second - generates a parabola with a focal length of about 12.5 cm.
As I recall, a telescope mirror designer named Roger Angel used this spin method to help build a mirror for a large telescope. I guess the idea is, if you can get close to the correct shape by spinning the glass, it will come close to the correct shape without a lot of grinding. Also liquid "mercury" telescopes have been tried in the past. Of course the limitation is that you can only look at objects at the zenith, unless you can develop some kind of mirror system to point elsewhere.
Congratulations! I have had the same project for years but I couldn't make it. What I want ot do is to use the liquid surface to "cast" polyimine resin. Why polyimine? Because it is the polymer that cover the IC packages for a very good reason it is "impervious" to temperature I mean it doesn't expand or contract so it is a much lighter alternative to glass in a telescope . And this is VERY, VERY important for my application. So instead of water I suggest you to use a viscose liquid like liquid paraffin or silicone ( I still have to check whether they are immiscible or not) and on top of this little by little add polyimine resin, as much as possible to form a parabolic shell of 2 to 3 millimetres. When you are happy with the liquid surface of polyimine you just start a UV light to start on the spot the polymerization. Having got a perfect polyimine parabola, the only thing is to put a reflecting surface of silver with a very simple chemical reaction that I have done several times or better to build a vacuum chamber (a frame and two strong glasses where is made the vacuum) and put aluminium wire on a wolfram light bulb filament and in the vacuum light the filament producing the aluminium deposition on the polyimine shell
Interesting fact that may or not have a connection to the black backing over the silver...the retina in the concavity of our eye has a black pigmentery layer behind the photoreceptors, it is thought that it does not allow light photons to bounce and therefore prevents blurryness of a double stimulation of our photoreceptors.
Nice video Dan. I'm currently working on a fluid-parabolic optical device. Will be posting a video of my work soon. I'll send it your way. I've been a fan of yours for a few years now. I just brought your channel up at a student engineering group at FSU.
0:12 The large wooden wheel that you made, looks exactly like a large wooden cable spool that the power comps use to run transmission line. But still a cool demonstration.
Have you tried the two-layer trick for this? Use runny epoxy to set a rough parabola, then after the first parabola has set, do another layer on top of that. You'll end up with an optic quality finish that's ready to be mirrored.
+GREENPOWERSCIENCE Now that I think of it, here's what would be the best way to use this: make a giant two-layer cast parabola as a positive mold to make a negative mold, and use that negative mold to manufacture multiple fiberglass/epoxy parabolas. Here's another idea: take the negative mold of an extra large parabola and slice it into six wedges, and make parabolic segments with a flange going around the edge. Then, you can transport the wedges where you need to in order to re-assemble them into one giant parabola that wouldn't be able to be easily transported otherwise.
Actually, as it was reported, the 94-inch mirror had NOT been parabolized as telescopic mirrors need to be. (Although Richard C. Hoagland doesn't believe that.) So some kind of corrective lens system was developed to correct for that, and Hubble photos greatly improved. Spinning a liquid naturally parabolizes it.
I've heard of proposals to use liquid mirror in micro-gravity environments on a gigantic scale. I've read about this principle, but I've never seen it in action...WOWWW!!
Hey, I was just wondering: have you thought about shortening the focal length on your fresnel lens setups (or super macro lens) by putting multiple lenses in series? I realize this might not make the setup much more compact, but I've been wondering if it could make the light converge much sharper, allowing greater temperatures in smaller areas.
So if the liquid is replace with some kind of epoxy or other type of setting fluid ,you make the mix and make it turn at a proper speed ,it would make a blank for a real mirror when it sets. Just have to silver it ... Is that your plan ?
Awesome Dan! I never thought lens were made in that way!!! Always thought lens were made on a mold or smth. I supposed centrifugal force done its job XD! I`ll make the experience!!!. Awesome again!
Thats actually how they formed the mirror for the ELT, and will form the mirrors for the Magellan telescope. 8 meter spinning furnace to cast the 25 ton glass mirror into a rough paraboloid to cut down the finish grinding time to years instead of decades.
Fire ants, termites in the base too, but the geared motor/generator still works perfect after total neglect. I was curious how they hold up to the elements. I just cleaned it up for a new video as it can output 255 peak watts. A one minute power ride can store enough to charge cell phones and small devices all day. Five minute leisure ride can store enough for 3 watts of LED lighting over a 12 hour period.
Okay, we've got the season left - just need some equipment to try it. But seriously, serious minded people wouldn't do this in freezing climate, but in a large freezer :) I just think the expansion of the water turning to ice will break the formation. Or then... I'd like to see it.
I have always wanted to make a telescope but the thought of the parabolic mirror has stopped me. SO... what liquids can we use that will harden correctly for a shallow mirror? I realize after the mirror is made I would need to adjust the secondary mirror until the right focal length is obtained that matches the first mirror. To me this is exciting. I have wanted a good telescope for at least 30 years.
Guess you've aleady thought of all the ideas, but in case not... I'm a big fan of modelling wax. Very runny at domestic oven temperature. Sets solid at room temperature. Even more solid when chilled. Maybe I'll have a go at trying it for this spinning technique. Use the wax "female" to cast a plaster "male" (thin layer at a time cos plaster warms up as it sets). Then make a fibreglass/resin dish on the plaster. What do you think?
Okto Putsch sorry, I haven't tried it. I'm not sure of the physics, which may lead to a swirling pattern on the surface (fluid dynamics is a bitch), and I don't need to make a parabolic mirror! I posted cos I vaguely remember being told about the idea. Not much to go on, sorry.
You won't be the first if you try. Newton has already done that. I would recommend putting the spinner inside a vacuum chamber so that the surface is undisturbed by waves.
What happens if you put a floating ball in it? Will it just go to the side if the pan? Go downhill to the center or float around like it's in flat non-moving water?
this is so cool. would it be possible to do this with molten aluminum for melting aluminum cans? If so, do you think this would be a good surface for making a telescope mirror?
Those 199 dislikes are either from people that know something we don't, or they're just haters. Any plans on making liquid telescope? The only problem with it will be inability to point it in any direction other than straight up
how about building up a quick-dry resin in incremental layers. Finally finishing it off with the final and top coat of slow dry resin. A bit time consuming, but anything worth doing usually is. I love the videos by the way.
You could build an 'approximate' surface out of resin, using any means at all (e.g. carve a mold out of wood) - and then use this technique to fill in the approximate surface to the proper surface. The liquid will flow to the proper shape even if the bottom of the container is uneven: when it reaches steady state, the liquid is not flowing, it's just all rotating around at the same rate as the form. So it's important to have a good bearing and very steady rotation.
Hi Stan. I love it. The resin thought is good. I tried a different route. I ground a 6 inch mirror, f6. Yet I polished the convex 'tool'. Did no proper figuring tests on the Convex Tool. Lined the CT to make a mould. Used a Thermoset plastic and a bit of heat to make a mirror and (gotta keep some of this to my chest), would you believe it, (not aluminized) could just barely make out craters on the Moon, details in nearby objects, trees, leaves and etc. Marriage woes (my ex thought I was in the shed making drugs ala Breaking Bad (amongst other things)), so I've had to put this little puppy on the backburner for a while. But I've kept most of the equipment and when I get the chance, will give it another crack.
How would you center the bowl perfectly in the middle to get the resin to for a centric parabola? you can see that the water level is a bit higher on one side and goes round and round... super
This has me wondering if you couldn't rotate a liquid material, let it cool while still rotating in shape, and then use a vacuum chamber to sputter coat with aluminum, copper, etc. Should be as precise, and much easier than grinding methods.
ingenius!!! Now I won't have to look for used satellite dishes! Could you use a magnetic fluid to have an infinitely variable lens? Or perhaps two layers of magnetic film with water in between, a magnetic field is drawn to form a lens.... No more need for those huge camera lenses!
That is actually how glass sheets were made for hundreds of years; until the industrial revolution. This is why windows in very old Gothic churches in Europe have very uneven thicknesses. The myth is that the glass has flowed or sagged after all this time, but the truth has to do with the way the glass was first made.
what about freezing it in situ (do it in winter?) then use it as a former for vacuum forming. silly idea but worth entertaining............. if you made the platform from several layers of MDF (very flat (and cheap)) & then mounted it on 3 rollers round the edge one of which was motorised you might get very smooth rotation & potentially a much bigger pool of water.......or you could make a battery-operated one that went in a deep freeze? I suppose it's simpler just to find a satellite dish
I thought of a better way using Mylar plastic sheet making it into a solid parabolic curve using can foam. Large mylar plastic sheet can be purchase from Ebay for $20, I think its like 4ft by 25ft.
I hope you will give some atention in what i will say. Do you know thats a great idea to make not only "Liquid Mirror" but if you put a kind of liquid that will get hard like rock you can make a real mirrors
GREENPOWERSCIENCE Awesome! will you be revisiting that project to refine the process? Although it does sem like it would also be much cheaper purchasing a large mirror instead of obtaining more gallium.
Even though this would work, it seems like work for nothing. A telescope made with glass will tilt any where and you can still use it??? Why bother with this.
The rotation speed is inverse to the square root of the desired focal length. rotation speed is sqrt( g/ (2*F) ) / (2*pi) where g is gravity (9.81 m/s2), F is the focal length in meters, and the result is in rotations per second. The rotation shown - about 1 rotation per second - generates a parabola with a focal length of about 12.5 cm.
smmmithhh. can u speek less smart
@smmmithhh Damn that’s crazy bro
@@tempest578 Unapologetically no, This is a really high quality instruction.
@@SouthernHerdsman dónde puedo comprar este líquido
Website?
Dan, you are an amazing person. You inspire me. Don't stop being you. Also, I believe this is the way the Mayans accurately mapped the stars.
Your videos always amaze me. They make me think about things I've never thought about before or in ways I've not thought about. Thank you!!!
As I recall, a telescope mirror designer named Roger Angel used this spin method to help build a mirror for a large telescope. I guess the idea is, if you can get close to the correct shape by spinning the glass, it will come close to the correct shape without a lot of grinding. Also liquid "mercury" telescopes have been tried in the past. Of course the limitation is that you can only look at objects at the zenith, unless you can develop some kind of mirror system to point elsewhere.
Bagaimana jika menggunakan resin?
I wish you were my neighbor. You are always expermenting on so many different things and making things from what you come up with.
Great Idea! Thank you for the comment.
Congratulations! I have had the same project for years but I couldn't make it. What I want ot do is to use the liquid surface to "cast" polyimine resin. Why polyimine? Because it is the polymer that cover the IC packages for a very good reason it is "impervious" to temperature I mean it doesn't expand or contract so it is a much lighter alternative to glass in a telescope . And this is VERY, VERY important for my application. So instead of water I suggest you to use a viscose liquid like liquid paraffin or silicone ( I still have to check whether they are immiscible or not) and on top of this little by little add polyimine resin, as much as possible to form a parabolic shell of 2 to 3 millimetres. When you are happy with the liquid surface of polyimine you just start a UV light to start on the spot the polymerization. Having got a perfect polyimine parabola, the only thing is to put a reflecting surface of silver with a very simple chemical reaction that I have done several times or better to build a vacuum chamber (a frame and two strong glasses where is made the vacuum) and put aluminium wire on a wolfram light bulb filament and in the vacuum light the filament producing the aluminium deposition on the polyimine shell
Dan, please shed some light on how you come up with these ideas. I really want to think about the world in a similar fashion. Love your videos!
You are a good science & technology teacher. It is just like saying an inch taller than Shakespeare.
Interesting fact that may or not have a connection to the black backing over the silver...the retina in the concavity of our eye has a black pigmentery layer behind the photoreceptors, it is thought that it does not allow light photons to bounce and therefore prevents blurryness of a double stimulation of our photoreceptors.
Nice video Dan. I'm currently working on a fluid-parabolic optical device. Will be posting a video of my work soon. I'll send it your way. I've been a fan of yours for a few years now. I just brought your channel up at a student engineering group at FSU.
We did this in Jr high with a turntable. Not everyone has a record player these days. Speed changes the focal point.
0:12 The large wooden wheel that you made, looks exactly like a large wooden cable spool that the power comps use to run transmission line. But still a cool demonstration.
The University of Arizona Mirror Lab uses this method to cast its large diameter short focal length mirrors
Have you tried the two-layer trick for this? Use runny epoxy to set a rough parabola, then after the first parabola has set, do another layer on top of that. You'll end up with an optic quality finish that's ready to be mirrored.
Thank you for the great idea. That should help the uneven cure rate. I will give it a shot. Thank you again.
+GREENPOWERSCIENCE I learned this trick from an old issue of Scientific American back when they featured how-to articles.
+GREENPOWERSCIENCE use Instacast but degas it in a vacuum chamber first.
+GREENPOWERSCIENCE Now that I think of it, here's what would be the best way to use this: make a giant two-layer cast parabola as a positive mold to make a negative mold, and use that negative mold to manufacture multiple fiberglass/epoxy parabolas.
Here's another idea: take the negative mold of an extra large parabola and slice it into six wedges, and make parabolic segments with a flange going around the edge. Then, you can transport the wedges where you need to in order to re-assemble them into one giant parabola that wouldn't be able to be easily transported otherwise.
@@Berkana donit jwst😊
Actually, as it was reported, the 94-inch mirror had NOT been parabolized as telescopic mirrors need to be. (Although Richard C. Hoagland doesn't believe that.) So some kind of corrective lens system was developed to correct for that, and Hubble photos greatly improved. Spinning a liquid naturally parabolizes it.
I've heard of proposals to use liquid mirror in micro-gravity environments on a gigantic scale. I've read about this principle, but I've never seen it in action...WOWWW!!
Reading the title made me feel smart :)
This would be a neat experiment to do in a freezing climate. You could make a parabolic ice lens.
Hey, I was just wondering: have you thought about shortening the focal length on your fresnel lens setups (or super macro lens) by putting multiple lenses in series? I realize this might not make the setup much more compact, but I've been wondering if it could make the light converge much sharper, allowing greater temperatures in smaller areas.
can you use your inventions for telescope purposes?
So if the liquid is replace with some kind of epoxy or other type of setting fluid ,you make the mix and make it turn at a proper speed ,it would make a blank for a real mirror when it sets. Just have to silver it ... Is that your plan ?
yes i think so but you could use also a cheaper concrete... where you from? italy spain?
Awesome Dan! I never thought lens were made in that way!!! Always thought lens were made on a mold or smth. I supposed centrifugal force done its job XD! I`ll make the experience!!!. Awesome again!
arquitectronico There is a Gallium video too: ua-cam.com/video/z7PdTWqu7mg/v-deo.html
Thats actually how they formed the mirror for the ELT, and will form the mirrors for the Magellan telescope. 8 meter spinning furnace to cast the 25 ton glass mirror into a rough paraboloid to cut down the finish grinding time to years instead of decades.
Fire ants, termites in the base too, but the geared motor/generator still works perfect after total neglect. I was curious how they hold up to the elements. I just cleaned it up for a new video as it can output 255 peak watts. A one minute power ride can store enough to charge cell phones and small devices all day. Five minute leisure ride can store enough for 3 watts of LED lighting over a 12 hour period.
Okay, we've got the season left - just need some equipment to try it. But seriously, serious minded people wouldn't do this in freezing climate, but in a large freezer :) I just think the expansion of the water turning to ice will break the formation. Or then... I'd like to see it.
Looks so weird when you zoom in on it. Makes me think the camera is moving in sync with the bowl.
Why did they stop making video?
I have always wanted to make a telescope but the thought of the parabolic mirror has stopped me. SO... what liquids can we use that will harden correctly for a shallow mirror? I realize after the mirror is made I would need to adjust the secondary mirror until the right focal length is obtained that matches the first mirror. To me this is exciting. I have wanted a good telescope for at least 30 years.
is that possible to use epoxy instead?
parabolic or circular?
Guess you've aleady thought of all the ideas, but in case not... I'm a big fan of modelling wax. Very runny at domestic oven temperature. Sets solid at room temperature. Even more solid when chilled. Maybe I'll have a go at trying it for this spinning technique. Use the wax "female" to cast a plaster "male" (thin layer at a time cos plaster warms up as it sets). Then make a fibreglass/resin dish on the plaster. What do you think?
I think it'll be quiet big to handle and manage but worths the challenge. Btw, have you done it since you posted this ?
Okto Putsch sorry, I haven't tried it. I'm not sure of the physics, which may lead to a swirling pattern on the surface (fluid dynamics is a bitch), and I don't need to make a parabolic mirror! I posted cos I vaguely remember being told about the idea. Not much to go on, sorry.
You won't be the first if you try. Newton has already done that. I would recommend putting the spinner inside a vacuum chamber so that the surface is undisturbed by waves.
Have you considered using mercury
I wonder if you could use a watery cement or plaster solution to create a dish?
What happens if you put a floating ball in it? Will it just go to the side if the pan? Go downhill to the center or float around like it's in flat non-moving water?
this is so cool. would it be possible to do this with molten aluminum for melting aluminum cans? If so, do you think this would be a good surface for making a telescope mirror?
awesome part of youtube again
I have 30 oz of pure Tin purchased 5 years ago. I will be trying that and lead if we get sun. 3 weeks of clouds and rain.
Those 199 dislikes are either from people that know something we don't, or they're just haters. Any plans on making liquid telescope? The only problem with it will be inability to point it in any direction other than straight up
Tilt the parabolic bowl
ceramic mud would also be an option- use glazing for the reflective properties.
Long time no hear, hope all is well:-)
how about building up a quick-dry resin in incremental layers. Finally finishing it off with the final and top coat of slow dry resin. A bit time consuming, but anything worth doing usually is. I love the videos by the way.
You could build an 'approximate' surface out of resin, using any means at all (e.g. carve a mold out of wood) - and then use this technique to fill in the approximate surface to the proper surface. The liquid will flow to the proper shape even if the bottom of the container is uneven: when it reaches steady state, the liquid is not flowing, it's just all rotating around at the same rate as the form. So it's important to have a good bearing and very steady rotation.
Hi Stan. I love it. The resin thought is good. I tried a different route. I ground a 6 inch mirror, f6. Yet I polished the convex 'tool'. Did no proper figuring tests on the Convex Tool. Lined the CT to make a mould. Used a Thermoset plastic and a bit of heat to make a mirror and (gotta keep some of this to my chest), would you believe it, (not aluminized) could just barely make out craters on the Moon, details in nearby objects, trees, leaves and etc. Marriage woes (my ex thought I was in the shed making drugs ala Breaking Bad (amongst other things)), so I've had to put this little puppy on the backburner for a while. But I've kept most of the equipment and when I get the chance, will give it another crack.
don't mention Crack
Have you found any equations that correlate the sagitta with angular velocity?
Do this with synthetic resin and coat it with something reflecting?
Where did I put my mercury
Thanx...looked like an Onyx stone until you put your finger in it. Rock on Dan
How would you center the bowl perfectly in the middle to get the resin to for a centric parabola?
you can see that the water level is a bit higher on one side and goes round and round...
super
+Yves Baggi If the resin cures equally. It is tricky because an uneven cure can cause the top to lift off.
Can I use magnetic stirrer?
How about making a video using a lens to heat 55 gallon drum for night heat in greenhouse?
Would love to hear about the resin mirror
Thank you for this video! It's fantastic! Just... don't hold the camera next time, please...
This has me wondering if you couldn't rotate a liquid material, let it cool while still rotating in shape, and then use a vacuum chamber to sputter coat with aluminum, copper, etc. Should be as precise, and much easier than grinding methods.
have you tried sump oil
ingenius!!! Now I won't have to look for used satellite dishes! Could you use a magnetic fluid to have an infinitely variable lens? Or perhaps two layers of magnetic film with water in between, a magnetic field is drawn to form a lens.... No more need for those huge camera lenses!
looks like a variation on dental casting techniques. Any interest in pouring molten aluminum while it spins?
that a great idea, then polish it while it spins too
Dónde puedo comprar este líquido
Congrats bro!
That is actually how glass sheets were made for hundreds of years; until the industrial revolution. This is why windows in very old Gothic churches in Europe have very uneven thicknesses. The myth is that the glass has flowed or sagged after all this time, but the truth has to do with the way the glass was first made.
Cool gizmo!
What the hell are "SPECULAR" ? (Title) and "Meeerr"? (Meeerr being constantly said throughout).
I think if you spin molten aluminum and then cover it with silver
have you made it from resin yet?? love to see that. Nice video ;-)
Freezing the water by cold weather you might have a giant , solid parabolic shape.
then cast resin on it once the surface is perfect?
You could make a mold this way with calciumsulfate and let it harden and then making a giant lens with water ice.
I wonder if you could setup a smaller version of this in a freezer. :3
Hello great video!! However i'm french and i don't really understand what's the black stuff that you have put inside the container... Is it resin??
It is just a painted surface. The liquid is water.
Is this actually a true parabolic shape or a spherical shape?
Parabola:
en.wikipedia.org/wiki/Liquid_mirror_telescope
Cool idea, great demo ... so, why did you do this ... what is it for. ;-)
The liquid telescope must always look straight up?
Yes
Mirrors, how do they work. Periscope.
You need to make the mold for the resin this way don't you if you want a lens?
what about freezing it in situ (do it in winter?) then use it as a former for vacuum forming.
silly idea but worth entertaining............. if you made the platform from several layers of MDF (very flat (and cheap)) & then mounted it on 3 rollers round the edge one of which was motorised you might get very smooth rotation & potentially a much bigger pool of water.......or you could make a battery-operated one that went in a deep freeze? I suppose it's simpler just to find a satellite dish
Why I want to sleep watching this turning table?
maricideva mega -- I got dizzy.
Then lucky me! :)
NOBODY'S GONNA RIDE THAT BIKE THRU POISON IVY
How? First Start?
A serious challenge to my vestibular system:)
Not planing on polishing lead. Not needed:
Sn=99% 30oz
Pb is from a 70/30 bar 43 pounds.
watch?v=_5NyZCu2d_c
12:30 in the video. That is a Pb Sn
what the hell did you say at the start?
I thought of a better way using Mylar plastic sheet making it into a solid parabolic curve using can foam. Large mylar plastic sheet can be purchase from Ebay for $20, I think its like 4ft by 25ft.
Wow.. about 1 minute in, I had to turn away and just listen.. I seriously thought I was going to puke. Cool video though.
No its not they all need to be ground and polished as you only get rough shape doing this
So this proves the earth is not moving.
buy a new brain
Eventuell mit Geschmolzenem Glas, das währe sehr Interesant.
I hope you will give some atention in what i will say. Do you know thats a great idea to make not only "Liquid Mirror" but if you put a kind of liquid that will get hard like rock you can make a real mirrors
Põe um líquido que endureça em pouco tempo.
Naw, I like those as well, because you are physically spinning with them. Did you research how motion sickness works yet?
Goog. Making it turn is one thing, but trying to observe the sky with it will be more difficult...
daym .. nice idea, but the spinning wheel made me feel queezy ...
Milan Gajic Sorry about that. The plank lines got me too.
That and the shakey cam
can´t you just use mylar,or a thin sheet of polished metal,and suck it from underneath ,what!?,with vacuum,ouch!?
You need to use a non Newtonian fluid.
Didn't shake the camera enough.
your a god...keeponkeepingon ,mattwhite would actually reflect more light (per se)
you should try it with gallium instead of water
ua-cam.com/video/z7PdTWqu7mg/v-deo.html
GREENPOWERSCIENCE
Awesome! will you be revisiting that project to refine the process? Although it does sem like it would also be much cheaper purchasing a large mirror instead of obtaining more gallium.
watch?v=z7PdTWqu7mg there is a link to a true mercury mirror.
Some telescopes use mercury.
no i can see with the camera shaking so much
Even though this would work, it seems like work for nothing. A telescope made with glass will tilt any where and you can still use it??? Why bother with this.
If it was cold enough it could harden into ice!
cool
Im dizzy thanks!