Artificial Sunlight (official topic)

As a seattle resident I am 100% behind this project. I just started off the build with a small satellite dish that my neighbor is getting rid off and tried two ways to make it reflective, using the reflective mirror vinyl tapes and the adhesive disco-ball mirrors.

The disco-ball mirrors are surprisingly easy to install, conformed to the curve and are collimating the light way better than I expected. Here is a picture with both installed half-and-half.

Another thing I noticed is that the LNB for the satellite dish is almost solid aluminium and very conductive. I will try to use it for both mounting the LED and attach the heatsink to see if I can get the LED in the perfect spot.

@nolo Hello Nolo! I live in Northern Sweden and I've chosen this project for my master thesis (except I'm in college, if that makes sense?). In two weeks I'm visiting the company SSAB in Luleå to hopefully lay my hands on a sonification device. Do you happen to have any titanium dioxide left and willing to send some? That would be a relief!

I'm very excited for this project since the sun doesn't rise for almost three months here and seasonal depression is a big thing. Also at my school everyone comes from the southern parts of the country which makes it even worse. If this works, I really believe it could make an impact here.

Hi Alex, I have sent you a private message.

@nolo Hello, I read the reply. Unfortunately I can't reply since I haven't made five posts yet. I'm working on it

Has anyone thought of microwaving the nano particles to disperse them?

@alex981 Not yet, but I don't think this would work.

Is the Tyndall effect affected more by the density of the nanoparticles in the epoxy sheet or the amount per surface area unit? Say I make the epoxy sheet 0.5 cm instead of 1, should the total amount of nanoparticles still remain the same given that the surface area is still the same or should there only be half as much?

If it only has to do with amount per area unit, a more versatile formula for the nano particles would be 1,3 grams/square meter instead of 0,01% of the total weight, which has been discussed earlier.

Old formula: Surface area in cm2 * 1,3 * 0,01% = weight of particles, in grams

1,3 g/cm2 is a common density of epoxy resin.

Correct me if I'm wrong, this is simply a thought I had.

@alex981 I think, that the amount of particles should be still the same, regardless of the thickness.

If you would use less, then the scattering would become weaker till only very tiny amounts of blue wavelengthes are being scattered. It also depends on the size of the partcles. I read somewhere, that the nanoparticles in our sky are below 1 nanometer, but as the sky has a very long path, it can result in the same effect as a thin epoxy sheet with larger particles i.e. 20 nm or bigger.

The amount and size of particles are therefore the most important factors. Also there is a maximum size of particles. I read that the particles or particle clusters should not exceed around 150 nm, otherwise the blue rayleigh scattering would turn in to "Mie" scattering, which clouds for example do, as the particle size and density is too high and sunlight gets reflected in white color (all wavelengthes of the light source are being scattered equally) instead of blue and some green.

This is the reason why we need to work with an ultrasonic probe device, which can seperate clusters of nanoparticles into reasonable small sizes, so that rayleigh scattering can take place.

If I did write something wrong, someone may correct me, this is all what I gathered from reading and some experimenting.

https://m.youtube.com/watch?v=mfAGivG9Koc

Instead of buying lots of lenses, apparently it's pretty easy to duplicate lenses with silicone and epoxy.

If I ever get the time, I'll try to duplicate my large fresnel lense with ti-infused epoxy. It would be an all-in-one solution to the problem.

I overlooked the fact that employing an achromatic lens could potentially eliminate all chromatic aberrations, adding a glassy touch to the optical perfection.

As for the projector, its construction is considerably simpler compared to a video projector since its primary task is to gracefully transmit the LED COB's radiance through a glass lens onto the wall. While I lack firsthand experience in crafting one, I believe it to be a feasible endeavor. Nevertheless, the initial step involves fabricating a PMMA sheet devoid of any bubbles, resembling a pristine piece of Rayleigh scattering glass.

Does anyone have the scoop on where I can locate the video or get the scoop on whipping up a simplified rendition of the artificial sun project? You know, the one with a box that's as enticing as a fresh batch of sjokoladebiter cookies, sporting a blue interior and a dazzling Fresnel lens. I heard whispers of its existence in the initial YouTube video release.

@lilon the simplest version is a white box, a fresnels lense, one or more waterproof printing sheet and a lightbulb with a neutral color temperature.