Artificial Sunlight (official topic)

I just found this project, and it's awesome. I'm following developments with interest.

But can I ask how it differs from this "Turning Smashed TVs into Realistic Artificial Daylight" project in practical terms.

I presume the brightness is the biggest difference. And the Rayleigh scattering is non existent on the TV project.

What about the parallelness of the light rays? The parabola obviously does an awesome job of that. The TV setup seems to be much more diffuse by comparison, there are no cast shadows. The output looks comparable a photographers soft box.

I'm keen on making a false skylight for a dark hallway. I'm dead keen on having it look as real as possible, but the size of the parabolic antenna and light arm will make it tough. 

Of course I'm thinking of how I could get it to tilt during the day to mimic the rotation of the Earth.

Does anyone have a finished example of the parabolic type artificial sunlight project they could hire to me for a film shoot in the UK (filming in Midlands)  ? Thanks, Chris. 

Further to my post yesterday, I've re-read the discussion and found the discussion between @nolo and @slojams about using the Rayleigh layer for the TV. I think I'll start with that.

I don't think I have the skills or funds to buy the mixer to make my own epoxy version. @nolo I'd be keen to buy some premixed hardener if you were interested in mixing some to sell. I'm in Switzerland for the next 6 weeks.

We've got an unused sat TV dish that I think I'll play around with, I have a 1500 lumen mountain bike light to use as the LED to start with. 

@nolo I just wanted to chime in and say how impressed I am with your clarity, effort and generosity. Wow. 

Thank you.

Agreed! It's actually quite a remarkable discovery and it's going to be very important in the DIY lighting space. I'm looking forward to trying it myself once the stuff arrives! @nolo I'll probably need some help though 😀 

@sethgodin Thank you very much for your kind words, I am glad, that I can share with you my discoveries and this project actually makes a lot of fun. I hope that more people will participate in this project "to transform our dingy homes into  vibrant spaces, full of life" 😀 I liked that sentence from Matt´s Video 😉

@diyperks Thank you too and if you have any questions, I am here to help and together we will perfect the process of making the panels. The basic knowledge is now here and we just have to improve the fine details.

Did you order the Ultrasonic probe from Alibaba and the particles from the german company already ?

BTW, I tested the PMMA stuff in the meanwhile and it is not recommended.

It was not the low viscosity that I hoped for and this stuff has an extreme odor to it. I had to open all windows for three days 😆 

Epoxy is much gentler on the nose and I will continue to use it instead of PMMA.

I may have some good news also to make it more affordable for everyone as the Ultrasonic probe is pretty expensive.

I mentioned earlier, that maybe we can use the high shear mixer instead to make the Nano particle dispersion.

The only thing is, that the mixer will not work with the high viscosity of the epoxy.

But I have a solution for this. The nano particles can also be dispersed in Acetone, which is compatible with epoxy.

Acetone has a viscosity similar to water and the high shear mixer may work here.

And Acetone has the benefit of quick evaporation. My idea is to disperse the particles with the high shear mixer in a small amount of Acetone and then mix this dispersion with the hardener of the epoxy. After mixing let the Aceton evaporate from the hardener, so only the dispersed TiO2 particles are left in the hardener after evaporation to not alter the properties of the finished epoxy sheet (strength of the material etc.)

Evaporation can be done by just letting the hardener sit 1 or 2 days at the shelf or even quicker by warming it up to maybe 50 degree Celsius or so.

If this method works we can from now on buy the mixer for around 100 euros and everybody interested in this project will be able to do it. The only question is, if the mixer can disperse the big nano agglomerates of the powder into smaller ones, so that rayleigh scattering takes place. I will order the high shear mixer and keep you updated if it works.

Regarding the molds for pouring in the epoxy to make the rayleigh scattering sheets I highly recomend using HDPE, because it's a non stick material and demolding the epoxy sheets is pretty easy. Here is a video about it:

Previously I used Multiplex Wood to build the mold and taped it inside with non stick tape and additionally sprayed it with mold release spray. With HDPE all this is not necessary.

And dont forget to level the mold with a level so the epoxy sheets come out straight (put for example small pieces of cardboard under the mold to level it or even buy levelling feet for the professional route). Also put some silicone inside between the base plate and the walls of the mold to prevent the epoxy from leaking out (let the silcone dry completely before pouring in the epoxy).

I have also some ideas to get the epoxy sheets bubble free, after testing various methods I also keep you updated.

@nolo you can use a vacuum chamber to remove bubbles from epoxy

Yeelight Skylight with real Rayleigh scattering panel.

Here is some demo:

Here is what's inside:

https://zhuanlan.zhihu.com/p/430543710

No fresnel lens or collimator film and from the comments seems that the leds are bad quality, but the most insteresting part is the Rayleigh scattering panel. If there would be any chance to order just those panels and larger, I could see a great project with some fresnel lens from old projection TVs.

I'm looking for a way to order this from Europe, but I can't find any dealers. Maybe because of some patent issue on that Rayleigh scattering panel? They are on Alibaba but you have to order 5....

Anyone knows how to order from 1688?

https://detail.1688.com/offer/677121796478.html?spm=a261b.8768355.pic-list.21.560a39aeLVpjcZ

They sell Rayleigh scattering panel up to 1220X2440

@bk88 Thank you, I had the exact thing in my mind. Vacuum chamber is the way to go. Additionally I would even like to try a pressure pot to put the vacuumed epoxy into the HDPE mold and let it cure inside. But there are no buyable pressure pots in the size of 50 x 50 or bigger as far as I know. But maybe the vacuum chamber is enough to produce a bubble free sheet.

All these pressure pots are round and for a square 50x50 cm sheet they even need to be bigger like 70x70 cm in order to get the mold inside. So that will be difficult, except for building a DIY pressure pot and buying a pump separately.

Regarding the high shear mixer, I dont recommend it. I have not been able to disperse the nano particles in the same manner as with the ultrasonic probe. The cheapest way is still to build a DIY ultrasonic probe, but the manufatured machines I linked to @ the Alibaba website are better IMHO, as they come with a control unit and a soundproofing box.

So expect at least 200 to 300 euros investment if you want to have a good working device. But I think still this is no problem, because if you think about what Coelux products cost and that you can easily sell the ultrasonic probe in the future for minimal money loss @ ebay for example after producing all sheets.

@bk88 Thats pretty cool if you can buy manufatured rayleigh scattering sheets !

I will study the website and try to order one with 60x60 cm. If everything went okay, I will write how you can order it.

hello, I am wondering if anyone has tried using those parabolic diffuser umbrellas as the reflector for this project. something like this: 

https://www.amazon.ca/Godox-Reflective-Umbrella-Lighting-Diffuser/dp/B07S4944G9/

Hi everyone,

just getting started in the world of trying to build an artificial skylight after seeing Matt's video.

I am very impressed with what y'all put together so far and would like to also get started.

@nolo Seeing as I am in Germany as well, are you interested in a quick phone call to get me up to speed on the current knowledge level, so we can go forward from there?

Can't be that impossible to manufacture a little nanoparticle dispersed plastic sheet. At least that's what my naive brain tells me 😀

I also watched your video and made a Rayleigh diffuser. Can simulate ultra-realistic blue sky and endless depth.

For an artificial sky, I don't think it's enough to just make the same blue as the sky. The sky fascinates us not because it is blue, but because it is infinitely deep. Blue is just a byproduct of the sky that fascinates us. Like the enchanting starry sky, it is black.

@devfoxrocks The low color temperature effect of making sunsets is something that Rayleigh diffusers cannot achieve, but can be achieved by changing the light source. The light source in Matt's video has only one color temperature, and we can switch to two color temperature lamp beads such as 1800K-7200K. When only 1800K color temperature lamp beads work, it can make the lamp glow amber at sunset. My ins (Pesetech) has the effect achieved by using two color temperature lamp beads.

Hi !! 

I'm quite new here, I saw the video when it was released and have been reflecting on it since then, but I just realized there was a topic on it !! 

First of all i'm astonished by your results and foundings, especially by the work of Nolo on "solid state" tyndall effect wich seems to have taken a lot of time to get right.

I would like to contribute by sharing some possible solutions for this problematic, that I imagined but never tried but could be very cheap to produce.

- The first possibility i see is to keep the classic "soap+distilled water" solution, but preventing it from leaking by adding some kind of jellifying agent (agar-agar is what comes to my mind first but it is made for food so maybe add a biocide in the mix), this could be very simple to pull off i think.

- The second solution I can imagine would be to "cheat" by not using the tyndall effect but simple diffusion. As I understand, the goal is to have warm-white rays coming from (close to) infinity, and blue rays coming from all directions. The way this could be replicated is by spraying tiny droplets of blue paint on the parabola and shining a neutral/warm-white LED (the color you want after scattering with the other methods) on it. The white light would still be travelling in parallels rays after hitting the parabola, but would also sometimes hit a blue droplet which would diffuse blue in every direction.

This solution makes the parabola the only blue zone, so it comes with a sacrifice because you can't have a full blue window unless the opening is inferior/equal to the size of the parabola. My solution would be to make a custom parabola (with 3d printing) which covers the entire emission angle of the led, this prevents the led from shining directly on nearby surfaces and means the parabola can be your fake window. 

I found that a parabola with a focal lenght of 10mm is sufficient to have <2 degrees angle between the rays (vs approx 0.6° for the sun) for a 10W diam. 6mm LED that emits light with a 120° angle, this could be a great way to make compacts ~50cm mini suns !!

would love to hear your thought on these <3 and sorry for my poor english I'm not a native speaker

@orphouille The sun is so far away from us that it is not a point light source but a parallel light source for us. Parallel light can be solved by Fresnel lens. Color temperature is relatively easy to solve. I made a video and sent it to my instrgam. (pesetech)

@orphouille

@noah I didn't know how to express briefly my point in english, what I want to say is that since the sun is not a point source, there can be as high as ~0.6° between two rays hitting the same spot ( the sun is approx 1,5*10^8km from earth and has a radius of approx 7*10^5km, the max angle between two rays 2*arctan(7/(1.5*10^3))=0.54° ). We can ignore this problematic for very large builds as the size of the led is very small compared to the focal lenght but as we try to go smaller we have to set a limit on how much deviation is acceptable since it affects the blurring of the shadows.

@orphouille This is a more difficult question. My idea is to have both an artificial sun and a blue sky. My company is a Chinese manufacturer and Matt's video helped me a lot when developing artificial sky lights. At present, the sales of our artificial sky lights have achieved good results, but I can only simulate the blue sky, but not the artificial sun. Maybe we can communicate in detail.

Hi Everyone,

Does anyone know where I could find the video or the details on how to build the simplified version of the artificial sun project? (the one with a box with the inside painted in blue and a Fresnel lens). There used to be a description of this in the first version of the video on Youtube.

Many thanks!

@nolo yes please post your instructions and material links!

@nolo great work! Can you please share some details with me? I am very interested and trying to recreate this project. TIA.

@nolo did you find any other sources for the nano particles. I was about to buy them from the link you posted but this postage was quite high. 35 euros to send to UK.

Hello Everyone,

I think I have a breakthrough idea, but don't have the means to test it. 

I've seen the DIY Perks video a long time ago and keep returning to it because the idea intrigues me due to my yearly winter decline in mood, even though I'm not quite ready to commit to making it.

There has been a lot of commotion about what dispersant to use for the Raleigh scattering effect, and how micronised TiO2 is too difficult to obtain and scatter into epoxy. I have an alternative, albeit somewhat hazardous idea that requires care and PPE (forgive me if it has been tried already).

FUMED SILICA is very epoxy compatable, often used in large quantities in order to reduce epoxy's density. However, it has a very, very fine article size, which lends it some light-diffusing properties that make it useful in consmetics. Perhaps adding a miniscule amount of fumed silica and dispersing it well can have the same effect as the soap & water technique. A thin layer can then be poured, and bubbles easily popped with a blow torch.

Most importantly, fumed silica is affordable and relatively easy to get ahold of, with multiple sellers on eBay. I believe the hydrophobic grade is the finest grade/most likely to work, but perhaps someone who has worked with the stuff can tune in. Provided you work carefully and with the correct PPE, vacuuming surfaces afterwards, it could be ideal. Especially is used to produce a large number of epoxy panels at a time. F.S. can have thixotropic properties, but I do not believe that it'd come into effect at such a low concentration.

If anyone has the financial or other incentive to work with F.S. safely, PLEASE do so, and provide us with an update. I believe I first encountered the use of fumed silica in an excellent video by Tech Ingredients on YouTube, titled "Super Strong Epoxy with Diamonds and More!", at around the 07:17 mark.

Best of luck, and please share if you have had any successes or failures.

@Noah

@Jordiemc

@nolo

@diyperks

I wonder if a Catadioptric lens could be used instead of a satellite dish to collimate the light. In combination with @nolo Rayleigh scattering epoxy sheet, you could significantly downsize the entire setup. Maybe...