Transcription

Daylight. There's nothing quite like the rising sun to get you ready for your day. And when it enters your home it can transform a dingy room into a vibrant and relaxing space. The warmth of the sun itself in combination with the fresh blue tones of the sky bring a vivid and lively feel to the light, making it utterly unique and something to be treasured. However, despite appearances, this is not actually early morning sunlight. To tell you the truth, it's actually night time and this is an artificial sun. And in this video I'm going to be showing you exactly how to build one. Everything you see here, from the accurate parallel shadows to the natural blue sky scattering, and even an apparent space of infinite depth behind the window, is all down to a unique design that can even be made out of recycled parts. This is going to be a good one. This video is sponsored by KiwiCo. More about them later. Making a convincing artificial sun does present a few challenges, the first of which is throwing the light source back so that it appears to be at infinity. You see, as the sun is so far away, when its light rays reach earth, they are practically parallel, which is one of the reasons for the sun's unique illumination characteristics like shadows that don't change in size. Interestingly, recreating these parallel rays with a local light source isn't particularly difficult as we can just use a lens. You see, when the lens is placed in front of the light at the lens's focal length, it actually collimates the light rays, which means that it makes them parallel. These newly collimated rays now have some of the characteristics of the sun, namely that the light intensity doesn't change because of distance alone, and shadows don't change in size either, which is super interesting to see. Another fascinating result is that anything at the lens's focal point appears to be pinned at infinity, and appears the same size no matter whether you're close to it or far away, as we observed in my recent DIY projector project. So success, right? Well, to a degree, yes, but the diameter of your lens directly dictates the size of your area of projected sunlight, so you need a massive lens to really get the best out of it if you're using a single point light source. And even if you use lenses of the Fresnel variety, this can get pretty expensive, and you still have some issues to contend with such as chromatic aberration, which is the rainbow effect you see at the edges. Thankfully, however, there's another way of collimating light rays, which is to use a parabolic reflector. Now this, just like a lens, can take light rays emitted at its focal point and bounce them back, but in a way that collimates them to be perfectly parallel, only this time without any chromatic aberration or distortion. Nice. Reflectors like this are just as expensive and hard to find as large lenses, however, or so you might assume until you realize that there might be one already attached to the side of your house. That's right, satellite dishes too are parabolic reflectors, intended to amplify distant radio signals by focusing them onto a single point. They're often off-center designs, which is why they're frequently oval shapes rather than round. The best part about utilizing these though is that used ones can be had for very cheap, or even free if they're old and need replacing. I'm using a big one here that measures 1.2m in diameter, which means that my area of projected artificial sunlight will be the same size as this. However, as you can see, it isn't reflective to visible light, so that's the thing we're going to have to fix first. One important thing to do before proceeding, however, is to give it a good clean, as this will get any dirt off, which means that it will be much better for the next step. If yours is super rusty like this one, you'll need to give it a thorough sanding down before applying a rust covering primer. Both of these prepping processes are important because we're going to be using vinyl mirror effect film to give it its required reflectivity, and we're going to cut it into strips so that it's easier to apply. Now you might be tempted to use some reflective foil tape here instead, but from my tests, the mirror film is significantly more reflective, so is definitely recommended, and you can find links to some in this video's description. It does take quite a while to stick on in strips, but once done you should have something that looks like this. With it now mirrored it's rather ironically very important to stop any sunlight from ever hitting it, as it could focus this light to a point and start a fire. So be careful. So this is looking really promising, but before we can test it out and see whether it's going to successfully collimate light rays, we need to sort out a light source. For this we are going to be using a high power LED, and as usual I recommend that you get one with a CRI of a minimum of 90, but ideally 95, and a colour temperature of 5600K. Now as these LEDs are so powerful they do generate heat, which means that they have to be used in combination with a heat sink. Now thankfully for 100 watt emitters you can get away with using a computer heat sink, which are super cheap to buy second hand, but for this project I thought I would go with something a bit more special, and I'm using a 500 watt LED from UGLED, and this is obviously very bright, but also it gets hot. So it's accompanying heat sink is unfortunately way oversized, very heavy, and very loud as well with the internal fan. So instead of using this massive heat sink which would probably bend the satellite dish's support arm, I'm going to be instead water cooling the LED, and the set of components I have here are from Alphacool, and I'm going to be introducing them and their function as I go along. The first component we're going to utilize is a water block, which internally has a lot of tiny fins that the water rushes through, taking heat away from the bottom plate. To interface this well with the LED and ensure good heat transfer, some thermal compound can be used, and then the whole thing can be clamped together with a custom bracket. Now this is actually going to be mounted in place of the satellite's original receiver, so after removing the original receiver a small bracket can be made out of a short length of aluminium angle which allows the LED to be mounted in place of the original receiver at the same position and angle. If you're using a lower power LED and just want to use a heat sink, this process is pretty much identical, and to power the LED you can just use a voltage regulator and an AC adapter. And this is a very good low-cost way of getting a lot of light output. However, as I'm using a much more powerful LED and water cooling, the process is a little bit more involved. And to get water to and from my LED there are some standard plumbing fittings on the back of the water block which allows some compression fittings to be used to securely mount some rubber tubing in place, which can then be routed down the arm along with the LED's power wire. Now as the power supply I'm using for my LED is super solid and heavy, not to mention waterproof, I made some custom brackets to mount the pump and reservoir combo unit directly to it, followed by the radiator. And this can be hooked up to the pump's inlet using a short length of tubing. The pump's outlet can now be connected straight up to the LED's water block and then returned through the radiator, completing the loop. So the last thing to do now is to fill it up. This process can take a while as it needs to be done bit by bit, running the pump in bursts to push the water into the loop. If you ever do this yourself, be careful to never run it dry as it relies on water for lubrication and it will likely get damaged if it's run without water in it. So with water rushing through now without any air pockets, some fans can be added to the radiator and the LED is ready to try out. Honestly, I forgot just how bright this LED is. Pretty incredible for being a single light source. But now it's time to mount it onto the satellite. To make a support for this, I screwed some pieces of wood together to make a triangular shape, which made it fairly easy to lift the satellite dish up into position. So as you can see, I've actually mounted the satellite dish upside down. And this is so that we can get a steeper angle on the light output. So it appears like it's coming from the sky and not the ground. And there are some really promising results actually from the reflection coming off the mirror, because the LED itself appears to stay the same size. So that does indicate to me that it is actually collimating the light. But we're really just going to have to try it out and see whether it works. So I haven't actually tried this yet. So I'm a little bit nervous. Right, are you ready? Here we go. Okay, whoa. Oh, wow. Okay, you can't see this because you're probably blinded by the light. But yeah, let me show you. As you can see, we have got parallel rays. If I move my hand close to the wall, its shadow doesn't change in size no matter where I am in the room, which is pretty impressive. Now if I look in the general direction of the light source, it does look like it's at infinity, which is super impressive. I can't look at it directly because it is a bit too bright. But just looking in the general direction of the satellite makes it seem apparent that it's in the distance, which is super cool. And what's more, it's absolutely pouring with rain outside, which might seem irrelevant. But the thing is, it's all sunny in here. For a bit more space, I've actually moved the satellite dish out into the hallway. And as you can see, the effect is really quite remarkable. This feels and looks just like daylight and looking at the light, not directly, of course, through the door, it does appear to be extremely far away. So mission accomplished. But there is one thing missing, which is, of course, the blue sky effect, which is fairly significant because the sunlight look will only properly come into fruition when the sky adds soft blue illumination to the room. So that's the thing we're going to have to sort out next. But before we get on with that, it's time for a quick ad from this video's sponsor, KiwiCo. KiwiCo makes super cool hands on projects and toys that are not only fun to construct, but they're also very educational as they've been designed to introduce kids to concepts in STEAM, which is science, technology, engineering, art and maths. So they're a great resource for learning at home. Each one contains everything you need for each project. So it's completely self contained with detailed kid friendly instructions and an educational magazine filled with content to learn even more about each crate's theme. Now, personally, this kind of thing is right up my street. And I've said before that younger me would have absolutely loved kits like this, as learning in a hands on way is far more interesting and far more engaging than learning, say, in front of a computer screen or from a textbook. And it has a whole different creative thought process that you learn from it. They offer eight subscription lines, each catering to different age group brackets and also different topics. And you can either go with a monthly subscription and get a new box every month, which you can cancel at any point, or a single gift, which is great for birthdays and special events. And what's more is that if you go to kiwico.com slash DIY perks 50, you get 50% off your first order of any crate, which is brilliant value, especially with the holidays coming up as they make great gifts. So thank you KiwiCo for sponsoring this video. And don't forget to check them out with the link below. So thanks to the satellite dish, our artificial sun is now at infinity, reproducing parallel rays that look and feel like sunlight. The real challenge for this build, however, is going to be mimicking a blue sky. You see, the reason why the sky appears blue is because molecules in the Earth's atmosphere actually bounce some of the light rays that are coming in from the sun off their initial path, which is a process known as Rayleigh scattering. As this has a greater effect on shorter wavelengths, blue light gets scattered quite a bit, while red light, for example, can pass through without being affected as much. This results in some of the white light from the sun diffusing into what we see as blue sky, leaving the sun itself to look more yellowy and warm as a result due to some of its blue light being scattered outwards. A great experiment for observing a similar effect at home can be done by getting a glass of warm water and dipping in a little bit of soap. As the soap dissolves into the water, it begins to scatter light in a similar way to the sky, making it look somewhat bluish. Looking through to a light directly behind it results in the light appearing more orange because a lot of its shorter wavelengths are getting scattered. This smaller scale phenomenon is known as the Tyndall effect, as it relies on much larger particles compared to Rayleigh scattering and can be seen in common materials such as HDPE milk cartons and opalescent glass. Now, one of the best ways of achieving this effect would be to use nanoparticles mixed into some sort of epoxy resin. However, despite a ton of research, I haven't been able to find a good source of nanoparticles that work as well as this. So if you guys have any suggestions, do let me know in the comments down below. But for this project, my conclusion is that the best way is to simply use soap and water as it's simple, safe and effective. However, how are we going to get water into the shape of a window? Well, we're just going to mimic a fish tank. For this, we'll need two sheets of tempered glass, and I suggest using an online calculator to work out what thickness you need for the size of your window. While it would be possible to glue these together with a spacer to make a 4mm deep watertight chamber, I'm instead going to be using a gasket and clamp the two pieces together with some 3D printed holders along with some washers and bolts. The plan here is to mount it directly to the back of a sheet of MDF, which has been painted to match the wall colour so that it blends in nicely around the doorframe, with the satellite dish behind it in the hallway. Watching for any leaks, some distilled water can now be siphoned into the chamber, making it ready for our soap mix. I ran out of distilled water at this point though, so instead I used filtered tap water. This does increase the likelihood of soap scum forming after a day or two though, which will need to be filtered out in a couple of passes over a couple of days, though this would be good practice to do even if you used distilled water here. And you may want to add a drop of biocide if you're going for extreme longevity. With the mix ready, it can be injected into the window with a plastic syringe. Look at that! As the soap enters the chamber, we can observe it instantly scattering the light from an LED I placed behind the glass. When you're doing this, I do suggest that you use the proper artificial sunlight to preview this instead, but I wanted to leave it for a big reveal. Over 24 hours, the soap mix will spread out and become evenly distributed, so why not in the meantime finish the scene off with some light curtains to make it look a bit more authentic. Right, are you guys ready? Here we go. Whoa! Look at that! Look at that! That really does feel like daylight. Goodness me. With the blue sky in place, the light suddenly becomes full of life and vibrancy, thanks in part to the sun taking on a warmer hue due to the scattering, with the rest of the room being lit softly by cooler blue tones. This has a dramatic effect on the overall feel of the light, and it now genuinely fools your brain into thinking that it's seeing, specifically, early morning sunlight. Both the parallel rays and their subsequent scattering are necessary for this effect, and neither will work without the other, so it makes for a perfect combination. Now, one of the most remarkable things about this light, I would say, is the way it makes you feel. It's actually night time right now, and it's so close to real daylight that it's completely fooled my brain, and I feel fresh and awake, and I'm doing the editing right now, so that's kind of important. But I would imagine that something like this would be really helpful for people with seasonal affective disorder, which is where people feel really depressed in the winter months where there's not much sunshine. And, you know, this being basically the same as real daylight should really boost people's moods. So it could be quite useful in that kind of situation, I'd have thought. But even just for a normal person, it just feels so vivid and full of life that every home should have one of these, especially in the long winter months, because honestly, it's incredible. I wish I could convey it enough to you, but hopefully my enthusing about it has done that. But you really do have to see it in person to truly appreciate it, but it's truly remarkable. Photographers and filmmakers would also benefit hugely from a light like this, as I know that for my own work here on YouTube, it's going to be a real help to my filming. So I hope you've all found this video interesting, and I hope my enthusiasm about this artificial sunlight has come over sufficiently enough, because it really is incredible, and it's been such a long-standing idea that I've had in my head that it's just so wonderful to see it come into fruition. And I hope you agree that it was worth the wait. So many thanks must go out to every one of you for watching this video, and if you enjoy my content, please don't forget to subscribe. And if you want to support the channel financially, you can find the channel's Patreon account at patreon.com slash DIYPerks, and many thanks if you decide to support me on there. But other than that, I'm Matt, you've been watching DIYPerks, and I hope I see you next time. Goodbye for now. It's so good. It's so good.