Very cool. I’m the CEO of Innerscene (https://innerscene.com) and we make a commercial artificial skylight that uses some of these concepts. Actually the coelux ht25 model is almost identical to what you made but using smaller lenses and more LEDs - however the effect they were able to achieve still isn’t that great, the sun looks like a giant orb and once you get a few feet away you can make out a sun at all. We spent a lot of time working on perfect collimation and hiding lens edges and making sure the view into the sky was seamless and artifact free. I’d say the last 10% of that problem is 90% of the work. :). I think we successfully cracked the nut but currently using a lot of expensive parts so working on brining the cost down. If you search Innerscene patent many of our approaches are spelled out. We also spent a lot of time on simulation and software…
Are you guys looking at fabbing your own LED dies?
The actual spectrum of commercial LEDs is all over the place when you start measuring it it with a spectrometer, even when they supposedly have a high CRI. Especially if you want some temperature that isn't 6500K.
It was so bad that when I was building a night light for my eink desktop I ended up using halogen bulbs which I could undervolt. The main issue was that I wanted to be able to shift the spectrum of the lights from natural sunlight at noon, down to candle light at night.
I did have big plans for doing a neural network to control a bunch of LEDs against a reference temperature, but having to build and calibrate a spectrometer and jig as part of a back prop algorithm was a bit beyond my interest, especially since for halogens I just needed a lookup table with temperatures to voltages that worked for all the bulbs from the lot I used.
there are companies that can do custom phosphor formulations for you to target a specific output. The minimum order quantities don’t make it practical for DIY but not too bad for a small startup. Our approach is to mix a bunch of different LEDs together to get the color and spectrum we want. Check out telelumen.com for an example that uses 16 chips. These are designed for researchers
I was doing something very similar to telelumen but given the variation in LED spectrum you could get off aliexpress in 2020 I could never hope to match their quality without tuning each led separately.
Looking at the spectrum graphs for your lights I'm seeing the telltale phosphor coating spike for both warm and cool white leds. An understandable tradeoff, but with the brightness of monochromatic LEDs you can get today one that's not essential any more.
With the drop in costs for both controllers and pcbs since then you should be able to get telelumen quality temperature spectra without the matching price, especially if you can get LEDs that have consistent spectra for their nominal wavelength - you only need to tune the controller once instead of for each light.
Yes, the more LEDs you mix the closer you can get to your target SPD but more LEDs also add cost and may not fit mechanically depending on how you are mixing them.
One other variable is energy efficiency, there are a lot energy codes around the world that limit how much energy you are allowed to use to light a space. In California for example it can be 0.6w per sqft. Sunlight is more like 100w/sqft so you end up having to optimize the spectrum for what humans can see and feel. I like to compare it with jpeg compression for light. In jpeg we throw away components you can’t see very well, you can do the same for light for an energy efficiency sake and maintain a close perceptual proxy.
We found 4 chips is a minimum bar for good light and use 5 for virtual sun - more info: https://www.innerscene.com/products/circadian-sky/CircadianS...
Are you hiring? I'm looking for a job currently. Contact info is on my website :)
Let’s chat! Are you the article author?
Yes that's me! Happy to chat :)
This is a great way to pitch for a job & half the interview is already done.
I adore the lights by your company, though they seem to be incredibly hard to source in general except for high end architectural projects. I wish there was an easier way to order them directly for DYI inclined engineers willing to pay the price.
Yeah - channels can be a pain, reach out to me directly if you run into issues: Jonathan @ Innerscene
Why not sell them directly, or via well known retailers, at the highest price point and with the longest warranty?
e.g. McMaster-Carr with a 10 year in-home repair warranty.
And you can still offer discounts via other lower price channels.
> 10 year in-home repair warranty.
The vendor travels to the house and repairs it? One warranty claim could wipe out a startup.
Do you not understand the concept of budgeting for warranty costs in the pricing?
Super interesting! Any idea how you guys compare with https://getchroma.co/products/skylight ?
I love the idea of high quality lighting inside especially for my Chicago place.
its tricky to compare because ours are designed to be integrated into a space and create the appearance of window with a big focus on high CCTs (2200k-40,000k) which relocates the color and spectrum of a blue sky using up to 180W. This lamp seems to be focused on lower CCTs (1800k-5000k) at high powers (750w is a lot of heat to dissipate). Both have similar Rf and CRI but we maintain great Rg and CRI across the whole range.
The one you linked is a stand alone lamp and they seem to focus on red light which I don’t quite understand. Red light (or very low CCTs) is used for skin therapy but typically requires direct exposure to the skin because irradiance levels need to be super high for that - from my understanding you wouldn’t have any benefit from a red lamp even at 750w. But blue light does can have lots of health benefits at low levels (search for ipRGCs).
Nitpick, but the image in "Innerscene Health Impacts" is very obviously AI generated, besides any personal opinions on GenAI it just looks bad. I suspect photographing the intern will yield something better.
Well, I think the challenge here is that they need to install the lights in all those settings to take the photo and this would be very expensive. The main purpose is to illustrate uses here, not show the final product. Maybe a disclaimer would help.
That’s kinda cool… is it possible to match the weather instead of “infinite blue skies” though?
I have real skylights on one side of my house and would love to put these up on the other but it would be weird to have sunny skies mixed with cloudy
Yes! We just announced and demoed a sensor that does just this at LEDucation last week and will be shipping before the end be of the year. It’s called SkySync
I never heard of this concept until this post, maybe because I live in a sunny country (Brazil) but I can totally see the use case for countries in higher latitudes, as the sun setting at 3pm mist be quite depressing for people. I wonder if you guys did any research on the effects of having your product in these countries. How much would the impact on well being be?
Yes, there is some really interesting research on this topic. It turns out that if blue light centered around 490nm is an order of magnitude more effective at treating SAD.
https://www.innerscene.com/papers/lux-vs-wavelength-in-light...
Because we recreate the blue sky there is a lot of light in this spectrum
I also live in a sunny country (Texas). But still I have "sun tubes"[0] in my house.
it is depressing, for issues see the condition Seasonal affective disorder (SAD)
The light here looks really good, but the cheaper (less nicer) alternative is just a powerful (natural) LED light - search for SAD lights
> If you search Innerscene patent many of our approaches are spelled out.
Subtle, nice. Maybe you can give the man a job. ;)
Not joking. Do these artificial sunlights help with the allergies? If yes and if it's not insanely costly I'd just try to get something like that for my bedroom during allergy seasons which most often coincides with no sun (winter, rain here). Even in those seasons when the sun comes out in its glory, the allergies (which mostly is my nose turning into an infinite source of salt water), which were driving me stark raving mad since days - at times weeks, might just vanish within an hour. Yeah, w/o even stepping into the sun. (And no, I am not D deficient.)
Hmm, never heard that before, I’ll have to research it more. Maybe the UV from sunlight is killing something you are allergic to. We don’t have UV for safety and energy efficiency reasons but you could try buying some strong UV lamps and see if that helps. Ideally you turn them on when you are out of the room so they don’t damage your eyes or cause cancer.
Oh, thanks. I will explore more on this.
I just want to emphasize how important it is for you to not be in the room with it when it's on. It can seriously damage you. There are stories of them being used at parties cause they looked cool and 12 hours later everyone is in the hospital cause it feels like their eyes are melting in permanent lava, their exposed skin is severely burned, it sounds like a horrible experience. Safety precautions are essential because it doesn't feel wrong when it's happening, but only hours after exposure. Also the lights can look really cool, so unsuspecting people may cause themselves serious damage without knowing.
Thank you for the detailed warning.
I actually decided to let go of this idea after OP’s warning and reading a bit about it. Because one problem will be that I will have to enter to switch off and on and even though it could be a short lived exposure I was scared. Though I’d read more on this what it could kill in the room. The thing is it might not help anyway. It is seasonal/situational and it happens in other places as well or outside if sun is not up. So whatever it is (general guess is pollen, dust, dust mite, sudden temperature changes?, general pollution etc) it is already in me or on me or everywhere around me. So I guess it might rather help more with an allergy test and if I am lucky I can find what I am allergic to.
UV is not so dangerous that you can't step in the room for a few seconds. Moreover, there's a significant number of precautionary measures you can take, like wearing UV-resistant sunglasses when you enter the room. There are also UV lamps that have timers on them, so you can have it automatically turn on and off when you're not there.
I would suggest you make sure you don't have any indoor mold. Mold in an apartment caused me problems some years ago. My understanding is that outdoor/natural mold is perfectly fine for most people (including me), but molds tend to incorporate whatever they consume into their spores, because molds prey on other molds so they try to arm themselves.
The problem is with manmade stuff like sheetrock, where the mold grows and then incorporates the binder chemicals into their spores, which are too small to see and yet get inhaled and then leech into our sinuses or whereever.
I've had problems in both work and home situations. I was tested and confirmed allergic; I don't think most people are, but it was rough for me. I'm always on the lookout for those water circles in drop ceilings; they're notorious mold colonies. Once a natural material stays wet for 12 hours, molds will begin to grow.
Just something you might be able to check off your list. Good luck.
Have you tried an air filter? A friend of mine has a bad hay fever but since he's put an air filter in his bedroom he can sleep soundly again.
Can either of your products be used on a table top or shelf or something like that w/o doing an installation? I saw your product priced at lightingdesignonline at a price I can afford, but I am in an apartment I rent that I cannot easily do renovations on. I don't care about the appearance of realism, just high quality light.
I was thinking of building my own, but you might have saved me from that. I couldn't find pricing for the modules on the website, but, if possible, I'd love to discuss this. My e-mail is easily findable on my profile. Also, there are no agents in Ireland.
This is simultaneously really cool technology, like a hyper-specialized analog light field display with health benefits, and yet there's also something dystopically unsettling about the sun being faked by a machine in a box.
Please don't have your marketing department destroy the real sun. Doing so would break antitrust regulations.
Yes! We started out building light field displays and originally used digital displays (arrays of micro LCD screens) - the result was super awesome but had a long road to becoming becoming a commercially viable product so pivoted to analog use cases which are a lot more energy efficient meaning we could achieve a lot brighter output.
“Virtual Sun” looks really cool. How much does one cost today? Say if someone wanted to buy a single piece or a few (2-3).
Pricing is ‘contact us’ and going to be region-dependent. I would expect to pay ca $ 10^4.5 for a panel that produces the ‘virtual sun’ effect. Same goes for competitors (I know of Coelux but maybe there are others. Not sure how quality/price compares). But maybe GP will reply to you.
Yes, it’s region specific. In the USA sales generally go through a partner. But it is a fraction of the weight, depth, and cost of the large coelux units that run $40k plus install. We also realized there is a need for producing just the sky with great photo metrics and that is even thinner and less expensive. A lot of interesting reading can be found in our interactive spec sheet here: https://www.innerscene.com/products/circadian-sky/CircadianS...
That's a fantastic spec sheet. Not talking about the specs, I have no idea how to read that, but it's very very well presented.
Thanks. This is our own custom PDF viewer. I made the page by generating images from a PDF and then overlaying transparent text so you can search and copy/paste. This allows us to make the PDF much more interactive (I.e. help topics, forms, etc) and allows us to create URL that link to specific pages or topics. You can actually save the page locally as a single file and open it locally and it still works, similar to a PDF. There is a script that bundles all the content into a single page as base64 data. As HtMl it loads a lot faster than a PDF and generally smaller. 10 years ago this would have been a major undertaking to create but with AI and rich libraries available today it was just a couple of days work.
Hope Oracle doesn't sue them somehow ;)
I'm very impressed that Innerscene provides LM-63 data for your artificial skylights. Is there any chance you'd be open to providing Spectral Similarity Index scores for your skylight? I think it would really differentiate your product and show how much your company cares about quality.
We provide full 1nm resolution SPDs in our download section so you can do any kind of calculations you want. Worth noting the SPDs change a lot depending on the color temperature of the light. In terms of similarity, trying to match sunlight exactly is not ideal because UV is bad for you and IR is a lot of water energy that can be produced in other ways more efficiently. For energy efficiency we focus on the spectrum that is most important for humans (versus plants, fish, etc). This is mostly the visible spectrum as align with our cones and the blue spectrum aligned with our ipRGCs. Most people don’t know about ipRGCs so we have a research page about this here: https://www.innerscene.com/research For the visible spectrum we target 90+ CRI for the full CCT range (3000-40,000k) but it goes as high as 98 and even R9 goes up to 9& as well. You might find this content about ipRGCs and melanopic light interesting
https://www.innerscene.com/products/circadian-sky/CircadianS...
I have a bunch of related questions so I will drop them all here:
* You mentioned focusing the spectrum on humans, but I have always wanted to have light that works well for both humans and plants (e.g. houseplants) as they are also beneficial for human spaces. Why not do both?
* Exposure to near IR has significant health benefits and seems like it should be included in an ideal lighting fixture that attempts to replicate the sun: https://pmc.ncbi.nlm.nih.gov/articles/PMC9855677/
What do you mean when you say IR can be produced in other ways more efficiently?
* How does your product compare with the Yuji Skyline?
For broadband IR, using a gas IR heater will give you the cheapest output - followed by an electric heater. Hard to compete with devices design specifically for heating when you are trying to do fancy optics in a compact form factor at the same time.
Yuji is similar to a lot of Chinese brands doing something similar which is a backlit Raileigh Scattering panel. The show images of the sun in their marketing and sharp sunbeams on the wall, but these are complete fiction. The also advertise color tuning, but the only natural color they can produce is a blue because Rayleigh Scattering doesn't allow very good color control. Still, for some applications like wall washing if you don't need a dynamic sky color and you can hide the view of the sun it could be a reasonable option.
We haven't researched plants a ton, but did some test to confirm they can grow under this light. Here is a cool time lapse video showing this in action: https://www.youtube.com/watch?v=2TDIVnXfE9I
Thank you! I’m sorry I overlooked those files. I greatly appreciate this perspective and research.
It’s clear that your company leaves no stone unturned.
I'm curious, why do you only sell via agents and provide no rough pricing information online?
I suspect that there are other people like me out there. Forcing me to talk to an agent to just get an idea of the price, even if I'm willing to pay a fair amount, is an automatic pass. A buy now button though, I'd be willing to do that and then discuss anything else.
Was the skylight in the season 25 episode of Grand Designs [1] made by your company?
[1] https://www.dailymotion.com/video/x97hx8g (from 39 mins in)
Yes! Good eye. They installed a pretty early version of our product - I think it took 4-5 years for the episode to finally come out
Hi, I couldn't figure it out on your site but on the picture where you have your hand under the virtual sun[1], do you feel the warmth of the "sun" on your hand as you'd feel it with the real sun?
[1] - https://www.innerscene.com/_next/image?url=%2F_next%2Fstatic...
No, there is no IR to speak of, however a lot of people tell us they feel warmer when they stand under it - just a psychological effect but interesting to observe
Would you ever consider making a product that emits some level of IR? Or even a very small amount of UV? Would be amazing for the winter months, even if it was just a very small amount.
UL safety cortication and energy regulations make it difficult to add UV and IR, UV because it can easily damage people's eyes and IR because it introduces too much heat which can be a fire or touch/burn risk. Energy regulations also limit how much wattage you can put into lighting, if most of that energy goes into creating IR (like real sunlight) then you won't comply with those regulations. For now it's better to buy a separate space heater to create IR, then you could also use a cheaper energy source like gas.
wow, these look awesome (on your marketing page ;)) I understand the pricing might depend on many factors including the location and the agent, but could you give a ballpark, such as "don't start looking for an agent if you want to spend less than X?"
What I learned over time is that if a product/service requires contacting an agent or a salesperson, then its price is only affordable for businesses and is not intended for regular consumers.
Does this actually give you the same intensity as sunlight? Or well, close enough to it that the light can diffuse into the rest of the room? In my experience my 4000lm projector doesn't have anywhere near the intensity to properly approach sunlight.
Outside direct sunlight can be 100,000 lux. With one fixture if you are standing in the sunbeam you are more likely to be at 2000 lux which is a long way off. You can add more fixtures to increase the light you are getting. However it turns out that one of the most important parts of natural light is “melanopic lux” which comes from light centered around 490nm (blue), if you get more or this spectrum it can have the same effect as having a lot more light from a low blue Light fixture. (I.e typical 2700k bulb) Some info about this; https://www.innerscene.com/products/circadian-sky/CircadianS... There is now a lot of research that looks into how much of this blue light you need and architects are starting to incorporate this into Building designs.
How do you guys go about doing sheet metal design? It looks pretty clean
Thanks! It’s powder coating that gives it a super clean look, great for sales demos but I’d suggest that anything not visible from the room side should be cost optimized
Yeah definitely, I’m more referring to the bending process, material selection, fastener types, etc. It seems like quite the art form
Oh, gotcha. we don’t do that in-house but lots of companies are available that specialize in this - probably one near you if search for sheet metal fabricators.
Totally makes sense that things like seamless edge blending and fine-tuned collimation end up being the biggest challenges
Are there any high-resolution photos of these panels in real spaces? I can only find renders.
here is an example install, this is not a render (the window is real but the skylight is not) https://www.innerscene.com/gallery/residential-virtual-sun
Here is a video showing the units suspended in the air https://www.dropbox.com/scl/fi/e0p4rsx31cqag42cklc61/A7_free...
It’s infuriating that you only have “accept all cookies” and no other options.
Oh but I do absolutely love this concept. I’m curious if you’ve had lots of interest from these billionaires building bunkers, if that story is even true!
Not a bunker per say but I recently learned that in some states/cities you don’t pay property taxes on square footage below ground so you end up with people building more space below than above ground and Virtual Sun can make it feel like above ground space. Just visited a billionaire project last week where this was the case.
Kinda hilarious that the people with the money to pay those property taxes would go to such lengths to avoid them.
Still, I'll keep this in mind on the off chance it ever becomes relevant to me.
For me, the problem with this setup (and with most high efficiency LED lights) is the lack of red wavelenghts. Real sunlight has a substantial amount of energy in the very red end of the visible spectrum (700 nm) and also of course quite a bit in the infrared. These lamps have two spectral peaks: a narrow peak in the blue range, around 450 nm, a broader peak in the green, centered around 580 nm. That greenish peak falls off sharply, and has almost no energy in the red end.
The color sensitive cones in our eye have three peaks of sensitivity, the S cones in the blue range, the M cones in the green, and the L cones in yellow. The L cones are what your brain uses to see red colors, but they are actually pretty insensitive to deep reds like 700 nm. That’s why you THINK that LED lamps produce red, because they stimulate your L cones, but they do so without actually emitting much red energy at all!
Our bodies are sensitive to deep red light. The cytochrome in our mitochondria respond to it. There’s an experiment where shining red lights on the skin improved sugar metabolism. That makes sense, because we naked apes evolved under red-rich sunlight.
So these lamps may look like sunlight, but they’re missing some crucial wavelengths.
That's a good point, but not much I can do about that. Such a DIY project is limited to off the shelf LED suppliers. It would be cool to do such a lamp with both the high CRI and some infrared, also for heating (infrared lamps are a thing after all).
I don’t think manufacturers will make LEDs with strong deep-red emission. If they made LEDs that emitted lots of red light, they probably would have a peak in the red end of the spectrum. But since they’re not monochromatic single-wavelength sources like lasers, there would be a spread of wavelengths around that red peak, including substantial infrared emission. And that IR emission makes heat, and now you’ve created an inefficient lamp, similar to the old incandescent filament lamps.
I'm just a customer of some their other products but... https://getchroma.co/products/skylight. (Of course as you know you're now drawing a ton of power for things other than lumens)
What you want is at odds with energy efficiency and is therefore being made illegal https://blog.medcram.com/uncategorized/new-department-of-ene...
Again, another regulatory decision that makes a niche worse off overall....
Abuses of a carve-out aside, having a "Sunlight mimicking" exemption would solve this, with the added conditions that they have to actually stick to the EMF outputs of the sun to get this approval. The article itself does this with “General Wellness Lamps”.
Otherwise, the only non-reg way to solve this would be to find infrared & red LEDs and make the supplementary light sources yourself.
I mean, wouldn't an IR carbon filament heater suffice? Probably a bit longer wavelengths, but you can still see it glow, so you're getting at least a bit close to the visible spectrum
> These lamps have two spectral peaks: a narrow peak in the blue range, around 450 nm, a broader peak in the green, centered around 580 nm. That greenish peak falls off sharply, and has almost no energy in the red end
Check figure 1h in the datasheet of the LEDs author used https://otmm.lumileds.com/adaptivemedia/832eef99dd3139f98fa9...
The second peak is near 650nm and while it drops fairly quickly there is still decent amount of power at even 700nm. In short, they perform far better than your stereotypical crappy white LEDs.
Yes, I saw those spectra. No, I don’t see very much energy emitted for wavelengths >700 nm.
If you look at spectra for stereotypical crappy white LEDs, they’re really no different. Everyone uses the same light emitting compounds, it seems to me.
Yep, that was my first assessment. Cant call it sun without NIR.
Can't call it sun without gravitational confinement nuclear fusion either.
you do you. NIR is the part of sunlight that makes you "feel" good or alive or whatever nice thing you are looking from being outside.. Ill stick with NIR is essential component for calling stream of photons as sun-like.. or not sun-like.
You can get LEDs which mimic the spectrum of natural light more closely, but these are usually specialty products (often specifically branded as sun-like). Here's one example https://www.greesled.com/wp-content/uploads/2024/11/ab24a411...
In comparison, the LEDs chosen by the OP have a fairly poor power distribution spectrum. At 4000K the color temperature is also too low to mimic daylight, which is at around 5500K. This is all well as an artistic choice but probably doesn't get you any benefits for seasonal affective disorder.
If the metric you're looking for is most accurate spectrum including deep red, near and far infrared (heat), then a good old incandescent filament light is the most efficient device. Not LEDs.
In the winter a couple incandescent lights per room is often enough to warm it up. I went out of my way this winter to "seal up" my house, and the equivalent of 2-3 bulbs per room is enough to keep them livable - with a sweater and a cap, and maybe socks. I cannot stand artificial heat, something about kt makes me physically uncomfortable, and i just want to leave an area with artificial heat. I'm fine with fires and incadescent bulbs, though.
> So these lamps may look like sunlight, but they’re missing some crucial wavelengths.
Which means they're also not going to give me a tan... bug, or feature?
Tan is the other end of the spectrum (UV)
They said crucial wavelengths, plural. I took that to its natural conclusion. ;)
It also won't be a great disinfectant, both in literal and figurative senses of the phrase.
My issue with this setup is that it doesn't emit as many neutrinos as the Sun.
I saw "artificial sunlight" and thought "oh wow I'd love to see the spectrogram of the lighting solution this person came up with". I was disappointed to merely see "CRI 95+".
https://www.youtube.com/watch?v=lH_owRxupC0
This is great video on the shortcomings of "CRI" - it explains in detail CRI, CRI extended, TLCI, TM-30, and SSI.
Brightness and color temperature are only two small parts of lighting - more people should start investigating the utility of taking their own spectroscopy measurements to figure out what lighting works best for them personally. My friends have very, very diverse opinions on what spectral distributions they like/hate, but they lack the language and experience to identify or communicate their preferences except for "Ooh I like/hate this bulb".
I mostly use LED bulbs to keep heat generation down (I pay for the heat twice in Houston: once to generate it and again for the A/C to negate it). But I always mix in a bit of incandescents / halogens (2400-3000K) which provide full-spectrum blackbody radiation to see ALL the wonderful colors in my world.
Do you have any insight on how to take spectroscopy measurements at home on a <1k€ budget? And how to select an LED manufacturing supplier when CRI is often the only thing available on the datasheet?
Starting points for first question: Look into i1Pro (later models of the first generation), which can be had for $200-400. Combine with some free or $99 Windows/Mac/Android software [0] [1].
Second question: It is still too hard even to find CRI for most offerings. It's pretty much a "buy, test, return the ones you don't like" situation. If independent reviewers start publishing spectrograms and making YouTube/etc videos, perhaps the industry will move forward some day.
A little garden spectrometer is pretty good, and around $60: https://www.youtube.com/watch?v=LxQmaJYMOAk . And the LED supplier should give a spectrometer graph. If you can get a dual peak LED that will give a better spectrum distribution. The Amaran 200x S is one of the best.
Very cool! I definitely want a spectrometer at home now! edit: looks like it's more of a DIY project than a commercial thing. Maybe DIY spectrometer is my next project then!
I bought a little garden on aliexpress from the guy who makes it. It's very plug and play and it does about 350-1100nm, which is pretty impressive. I used it to verify how my own DIY sun reproduction setup works. https://www.aliexpress.us/item/3256807055520087.html
There is also this commercial one that is Bluetooth and more portable for around $150, similar spectrum range but lower spectrum resolution than the little garden one. https://www.youtube.com/watch?v=MOXryggwr_Q
https://www.amazon.com/Analytical-Wavelength-340-1000nm-Spec...
The hopocolor vis light ones are also fairly widespread and are more stand alone for about $280: https://www.aliexpress.us/item/3256807972511960.html
My current issue is finding a 250-400nm UV spectrometer or IR spectrometers beyond 1000nm that don't go into the $1000+ range. Standard mass market CMOS sensors don't go into those ranges, so they become far more specialized parts and thus way more pricy.
Mid level, $750: https://www.aseq-instruments.com/LR1.html
Entry (?) untested, $350: https://thunderoptics.fr/product/sma-e-spectrometer/
The luxeon 2835 website that’s linked in the article has a data sheet for the LED source. Scroll down and you’ll see the spectra for various subtypes of that source.
With some LEDs, and especially the warm whites, I get this feeling of „artificiality“, for lack of a better word. Like the surroundings are somehow fabricated. It’s an interesting idea to mix and match those with other light sources, I‘m going to try that.
I think most people at least know the difference between warm and cool light, which helps a lot, but otherwise I agree. As I’m reading this, I’m realizing I have no vocabulary for this topic. That’s… kinda strange to experience!
Huh, incandescents have been banned here (Australia) for years. Even compact fluorescents are out.
There appear to be enough loopholes and lack of enforcement that you can still piece a solution together: https://electricalproducts.com.au/incandescent-lamps.html?p=...
Cool, but you can get brightness enhancement film for very cheap in AliExpress: https://www.aliexpress.com/i/2255799825024246.html
The brightness enhancement film is a transparent optical film. It consists of a three-layer structure. The bottom layer of the light-incident surface needs to provide a certain degree of haze by back coating, the middle layer is a transparent PET substrate layer, and the upper layer of light-emitting cotton. It is a microprism structure. When the microprism layer passes through the fine prism structure of the surface layer, the light intensity distribution is controlled by refraction, total reflection, light accumulation, etc., and the light scattered by the light source is concentrated toward the front side, and the unused light outside the viewing angle passes through the light.
So, it's similar to your design, but the grooves are very small.
Really cool! I'm working on a lamp that gives you daylight levels of light indoors (albeit no raleigh scattering and columnated light). On the bright side (pun intended), it's 50,000 lumens instead of ~4500. https://getbrighter.com/
Nice to see more high quality indoor light options. Any idea how you guys compare to this one? https://getchroma.co/products/skylight. I've got some of their other products - I'm generally been pretty happy with them but they do tend to be fairly pricey.
He hasn't given a spectrometer graph? When you ask him for one he can't seem to be bothered by something so basic either. I don't think he would beat an array of 4 amaran 200x S lights on light output or spectrum quality beyond the dimming method.
Had the chance to see one of these in person - did not believe you could achieve “daylight indoors” before I did.
If you have a chance to chat with the staff again, I notice their marketing language says "Nearly perfect spectrum matching with daylight" - but they don't publish a Spectral Similarity Index. They only claim a (relatively low) CRI of 90+.
Edit: In other materials, they claim a very high CRI of 95+. Also the advertised wattage is sometimes 400W, other times 500W.
I have a 200W LED flood light and it was the most depressing thing to shine indoors. EVERYTHING was covered in dust and filth that you wouldn't see under normal-intensity light. It felt like things had collapsed and I was surveying the remains of someone's house.
I'm 100% your audience for this, all I want is for it to be able to automatically adjust it's color temperature throughout the day and I'd replace every Hue bulb in my house with it - can it do that?
Yep you can schedule it to get brighter/dimmer and warmer/cooler from your existing [Matter compatible] smart home system, and with HomeKit adaptive lighting you can have it follow the sun.
500 watts! I won't need a heater any more if I turn one of these on. I had a 10k lumen led matrix lamp, but I found that it completely threw off my natural rhythm to sit under it for any length of time. It felt like it was perpetually early morning.
Oh this is cool! Reminds me of led grow lights. You can get a panel with hundreds of LEDs on it for growing plants for like $200
I snagged a couple preorders upon seeing this comment, since I realized I forgot to do that before.
DIY Perks also attempted to make artificial sunlight at home, also focusing on things like Rayleigh scattering! This was a great watch:
https://www.youtube.com/watch?v=6bqBsHSwPgw
EDIT: After reading the article, I see the OP calls out DIY Perks specifically - the OPs design is much more compact :)
> It's compact. The total size is 19cm x 19cm x 9cm. This is quite compact for a 5cm focal length and an effective lighting area of 18cm x 18cm. Reflective designs like the DIYPerks video or commercial products like CoeLux do not achieve this form factor.
If you want a jankier but cheaper version, here's a (much less nice) version for about $50: https://worstplans.com/2021/05/10/led-artificial-skylight-fo...
It uses a trash can plus a super-bright LED bulb plus a plastic book magnifier.
The main trick is that you can get a big magazine-sized flat plastic fresnel lens for like 10 bucks.
The original poster's solution is definitely better, but it's also possible to do this on the cheap with no 3D printing (or in fact, any skills whatsoever).
> the main thermal issue when scaling up would be the cooling of the power supply itself, not of the lamp
If I would be scaling up that device, I would consider an ATX power supply. These are relatively large and typically include an active cooler inside, but they can easily supply hundreds of watts at 12V, often have an on/off switch on the back, are relatively inexpensive (at least unless you need much more than 500W of power), and are available everywhere. Usually, you just need to connect the PS_ON wire with the ground to make them turn on once powered.
Could you wire them in parallel for more watts
Personally, I would avoid it if possible. Even if they are of the same model, small discrepancies may cause their +12V to be slightly different. At the very least, will cause very non-uniform load distribution.
Luckily, seems the OP only needs one. The current light only uses 36W @ 12V, even if they make the new light 10x more powerful, a single 400W PSU should do the job nicely.
It's not like the fixtures consist of a single LED either. Should be trivial to parallelize.
What about wiring them in parallel with a voltage regular after.
Then you waste a ton of energy on the conversion and still have the same problem. You won't ever get two regulators at exactly the same voltage. One will always take most of the load.
You get around this with load balancing resistors, but that comes with its own set of problems.
The way you get around that is to chop up your load into multiple independent power domains. That way each segment is powered exclusively by one supply.
If you can't do that, you will always be better off with a single larger supply.
I meant in parallel so both positive terminals are connected to the regular in one node
Imagine one PSU outputs 12.0V another one 12.1V, and there’s no load whatsoever.
When you connect them in parallel, the first PSU should detect negative load i.e. actual voltage lather than the target; I have no idea how real-world devices handle that condition.
The second PSU will detect load i.e. actual voltage smaller than the target one, will probably assume it happens because the load is pulling energy and will try to extract more power form the AC source to compensate, to make the output stay at the +12.1V target.
I’m not an expert electronics engineer, but to me the approach looks like a recipe for disaster.
It’s usually fine to connect chemical batteries in parallel for two reasons. They have that discharge curve i.e. the voltage decreases monotonously while discharging. If one of them has slightly higher initial voltage, will discharge until matched with the other one, and then both will discharge at about the same rate. Also, chemical batteries have ~fixed internal resistance i.e. the more current you pull from one, the less voltage you get due to that internal resistance.
AC to DC power supplies don’t have a discharge curve because nothing to discharge, they continuously pull energy from the input AC. They don’t have the concept of internal resistance either: when more output current is pulled from them (i.e. the load increases), they simply increase input current from AC (to a point, and then either a fuse blows up or the device catches fire). The dependency between output current and output voltage is not necessarily monotonous. But the worst of it, it depends on time because capacitors, also because the input is single-phase AC i.e. at some moments of time the input power is zero because the input AC voltage and current are zero.
At that point you might be better off getting a power distributor from an old server that was already designed to operate off redundant 12V power supplies. But you wouldn't want the server PSUs themselves due to the tiny loud fans.
There already exists a fairly good replica of sunlight, Philips CDM. I used it when I was growing weed, lushest bushes I’ve ever seen. 10/10 buds.
It was discontinued for a while but I’m happy to see it’s back in production?
https://www.futuregarden.co.uk/philips-ceramic-discharge-met...
I would pick a CDM bulb any day over the alternatives, including LED, unless power consumption is an issue.
“ Philips daylight CDM lamps are extremely efficient ceramic metal halide lamps with a spectral output close to natural sunlight. As a result, plants form more lateral branches, have smaller inter-nodal spacing, more flowering sites, and larger root systems, culminating in strong, healthy growth and high-quality yields.
Philips CDM bulbs have an amazing operating life. They maintain their high output for a lifespan of 30,000hrs on average.”
Is there a reason why you went with traces rather than pours? I count 7 signals per board, and they're all meant to be low impedance. You could even expose copper on the back of the board to be used as ad hoc heat sinks without spending any extra money. The weird little triangle loops on the back really stand out to me, even though you probably don't need to worry about the impacts of a loop in your circuit.
Thanks for the feedback. Everything I know about PCB design is self-taught. I'm a total beginner, so I'm sure there's a lot to improve!
There's only 2 routes per board, VCC and GND. I initially planned for SMD header pins that I didn't end up using, because soldering wire on bare pads was good enough. I also planned for 8 connection pads per PCB, but only used 2 to 4 in the final assembly. So yeah, lots of room for improvements in the PCB design! Definitely would need to spend some time on it for a higher power version 2.
My first few boards had exactly the same problem, it wasn't mentioned in any of the tutorials that I watched. All you need to do is add a fill region that encloses the whole board, and usually set it to GND.
You probably don't need to worry about EMI and EMC with DC, but if you want to make these dimmable you definitely want a ground pour "behind" any high frequency lines. You additionally don't need to worry about that if you aren't manufacturing, but it's still worth learning it the right way IMO. The sig/pwr-gnd-gnd-sig/pwr stack-up is well worth getting into the habit of (it has great EMI characteristics), and translates relatively easily to gnd-sig/pwr-sig/pwr-gnd stack-up once you've nailed down the design (which has amazing EMI characteristics).
Rick Hartley made these stack-ups popular (if he didn't outright invent them): https://youtu.be/52fxuRGifLU?si=8W1WXfJRHg3Oeep5
I'd be interested in seeing the optical spectrograph of the LEDs. If you want to simulate sunlight you want a full-spectrum LED like a Samsung LM301 series LED which are popular in grow lights. Not all LEDs are created equal, and even the LEDs in many "grow" lights only show two sharp peaks at red and blue wavelengths. A full-spectrum LED will output colors across the visible spectrum of light. You can't tell by looking at them, so you can either buy ones from which you trust the manufacturer or do what I did and build a cheap optical spectroscope using a raspberry pi with a small camera attached, a spectroscope lens, and some python code. I'm sure there are guides you can find with a quick web search if interested in making one.
This is covered by the CRI95+ value, note that the LM301 you mentioned only has a color rendering index of 70. Maybe it has predominant wavelengths that are relevant for plant growth, I don't know, but a CRI of 70 isn't impressive at all.
For an accurate rendering of the suns spectrum you basically would like to simulate the spectrum of a blackbody radiator with a surface temperature of 5500°C minus the absorption bands of water vapors, atmospheric gases thst are typically inbetween the sun and us. Also note that the suns spectrum extends both above and below the visible range, which gives you the feeling of warmth (infrared) and tan/sunburn (ultraviolet).
In reality most commercially available LEDs still have a extremely spikey spectrum compared to sunlight — this can be somewhat fixed by mixing different LED types and adding filters. But this is only done in extremely expensive movie lights like Arri skypanels.
Thanks for the insight. Most of what I know about LEDs, and specifically the LM301 series, comes from research I did prior to setting up a small indoor grow tent several years ago. It was a "spikey spectrum" precisely that I was trying to avoid. For growing Cannabis you do want spikes at red and blue, but better LEDs also emit a wider spectrum along with the spikes and that results in a better result. Having only spikes at red and blue alone works, but not as well. The lights I ended up buying had LM301H EVO LEDs with a CRI of 80 and were designed for a 2'x2' tent. You can also get LM301H LEDs with a CRI of up to 90, though. The lights I ended up buying only cost 80 BezosBucks at the time. I don't spend BezosBucks anymore, though, due to enshittification of everything Amazon, but I digress.
While they aren't designed for growing, and to use them would be a complete waste of $8k, I bet the Arri SkyPanel S120-C SoftLight with a CRI of 95 would do a fine job for growing. You weren't kidding about them being extremely expensive.
The LED datasheet has Typical normalized power vs. wavelength graph (figure 1h) https://otmm.lumileds.com/adaptivemedia/832eef99dd3139f98fa9...
I did something similar last year, but I was more focused on spectrum and used high powered movie lights, since their spectrum output is much better and you get a lot of lux. You can get most of the parallel light ray effect by adding a hyperrefelector which conveniently comes with most lights. I then added an incandescent heat lamp to fill in the IR part of the spectrum and some dedicated UV LED lights for the UVA part. I'm not brave enough to put in a UVB specific lamp.
I wrote about it here: https://metrep.substack.com/p/improve-your-focus-productivit...
I’ve been thinking about the potential benefits of incorporating something like this into VR headsets. Since VR already controls the user’s visual perception, would adding a high-intensity blue light (not via the OLED displays but indirectly) allow for a more effective way to simulate bright daylight conditions? Achieving 10,000 lux at the eye would be much easier this way.
Those in dark winter places can check this out for a home bright light setup.
Some people report much better mood in dark winter days:
https://meaningness.com/sad-light-led-lux
https://meaningness.com/sad-light-lumens
Buy a cheap lux meter if you will be doing this since otherwise you are flying blind.
This definitely helps for me, but it's hard to place the lights without glare, since they can't be anywhere that's ever directly in your vision! I'm also a little worried it's going to burn the houseplant near it.
But it was a big change; my Silicon Valley apartment has little overhead lighting, and I mostly use Hue lights which just don't get very bright, so it turned out I'd accidentally built a depression cave in the winter.
Personally, I hate overhead lighting and much prefer lamps or wall sconce type of lighting. I did replace my overhead bulbs with Hue bulbs, but I don't feel the not very bright aspect. My overhead bulbs are most often at 25%. Anything over 50% is just too much for me. I love my Hue lights and am trying to switch over to all Hue bulbs. I still have a few regular bulbs in places that just don't get a lot of use, so they get ignored
The 1600 lumen bulbs are worth it - if they fit your fixtures.
Still nowhere near as bright as a window on a cloudy day though.
Part of my problem is my place has a lot of windows and is on the ground floor. So those are both good things, but the combination means I have to keep the curtains closed to maintain any privacy. Lighter curtains or something might help.
I've been down the artificial sunlight at home rabbit hole too (also inspired by the same DIY Perks video). Ultimately the solution I settled on was a much lower budget 300W equiv LED Corn style bulb (4000lm) with good CRI, and a 250w incandescent heat lamp (like you'd get for a reptile). I decided to focus on heat from the light source rather than the parallel rays. Total cost was around $75 (LEDs were $25 for 2, heat lamp was $10 for 2, plus $20 each for 2 lamp stands that clamp to a desk and can support 250 watts).
Really neat, thank you for posting. I took a different angle when trying to figure this out - my goals were high spectral similarity to the sun, high brightness, adjustable warmth, and low cost. The existing lower-cost solutions people have posted about end up with high brightness, but the lights are evil.
I ended up with a photography light that's /alright/. It's not nearly as bright as I want, and I can't automate changing the warmth. When I next take a crack at this, I'll look deeper into some of what you've posted about here.
Thanks! Feel free to reach out, I love to chat about this stuff. Contact info is on my website.
https://store.yujiintl.com/ has broad spectrum LEDs/lamps/fake skylights that may also appeal to others interested in the OP--just noticed Yuji was mentioned in OP. I'm not affiliated with Yuji but have ordered some of their products and been very happy with their performance.
Ah... the intensity, not actual nuclear fusion. Well, still a nice project!
I cannot remember if I first saw this here on HN but, here is a detailed video of an incredible artificial sunlight rig build. It's big but the results look, well, amazingly real, at least to the camera.
This was referenced in the article.
Yeah, and right up front, too. I noticed that only after it was too late to delete my comment.
Projects like this are a great demonstration of just how far hobby projects can go today by exploiting some fairly recent innovations. In particular, designing a custom lens geometry and having JLC manufacture small runs cheaply is especially impressive; and of course, what you can get out of a modern LED is just absurd.
I agree, thanks for underlying that point. I did not intend to write an ad for JLCPCB, but honestly I kinda did. I feel like it's deserved praise because the service is really great. Low volume custom PCBs with assembly service and 5 axis CNC with a minimum order quantity of 1 is game changer for prototyping. Combined with a software first approach to design with tools like build123d, the flexibility of 3D printing and 5 axis CNC, and the addictiveness of the high dopamine feedback loop of software dev starts to bleed over to hardware dev. Shipping delay is the last hurdle.
About the lenses, I did consider injection molding during design, and one supplier even quoted me for $20,000. So yeah, very glad for JLC!
I remembered seeing, loving, and saving that original DIY Sunlight video back when it first came out, and I went to your article hoping for more, and that's what you gave us. Brilliant job, and thanks for sharing!
I built a very bright light source using a lamp stand from Ikea and the brightest, narrowest beam LED reflector I could find from my big box hardware store. The project works and gave about 10,000 lux but had a few drawbacks. After reading a book for a while a got a headache. The slightest imperfection (read dirt) in the arms of the armchair becomes super obvious. When I look at my right arm holding the book, it's so bright I'm sure I can see veins and arteries. I ended up getting a lamp less bright and that's great for sewing/electronics/fine work but there are limits for how bright you might want to go indoors. I kept the too bright globe for demonstration purposes.
The headache could have been from LED flicker. I bought a corn cob LED bulb and it had some high frequency flicker that was visible when using a camera with no anti-flicker compensation.
Why did you want a very narrow beam? It seems like the opposite of what you would want from a lamp but I think I'm misunderstanding. And do you have the name of the less bright lamp you got?
This is super cool, and a great project.
As someone more on the software side as well, I’m inspired to take on something similar.
But more importantly, as someone who rented a windowless room for a year, I would have loved to make a smart light like this to wake up to in the morning.
> windowless room
Thankfully that's illegal where I live. I'm even tempted to suppress my own work here, because I don't want it to be used to unlock new levels of dystopic housing.
Just kidding, thanks for the feedback!
This is one of the most satisfying DIY reads I've seen in a while. I love how you approached this as a software dev and essentially built a full stack for hardware iteration.
It you put out enough light, you can diffuse it more, such as by bouncing off the ceiling or a light-colored wall.
You can also use photography modifiers, like the various kinds of reflectors. Even white photo lighting umbrellas (which you shine a bright light through) help a lot.
Whether or not you add diffusing, you might want to make your light source mountable on a photo studio light stand, so that you can position and aim it however you want (just like you would with a studio strobe or hotlight).
Years ago, I remember seeing that a firm was using fiber optic bundles to bring sunlight in from the roof into the inner spaces of an office building.
Does anyone know anything about that?
I've been tracking that on and off for years - https://parans.com/
Not sure it's really caught on, but it's out there
Thanks! That looks like it.
I wonder what the light's spectra and intensity are.
I'm guessing that its cost is prohibitive, or maybe the light's characteristics are just not so great.
I'd love to be able to do some low-intensity tanning at home, for vitamin D and skin health.
Thanks a ton.
Very cool. I do think the DIY perks version just pops a little nicer but it could also be the photography of the project. But the firm factor if your project is much nicer as well. I think both projects would be better suited for different needs so again very cool. If you had lots of space the diy perks would be the way to go. If you only have a thin wall or ceiling then yours would be best. All in all thanks for posting this.
It's partly the photography but definitely the reality as well. Mine is only 0.03m², the DIYPerks parabolic reflector is 1.13m² :)
One of my goals was to explore the feasibility and scalability of a refraction based design.
Wait, you can order custom fabrication of lenses online?
Turns out you can yeah! I'm not sure the quality would be anything useful for imaging applications though. But for lighting / non-imaging stuff go for it!
Well, there goes my idea of DIYing a telescope...
It's not that hard to find decent lenses. I bought a lens with a long focal length and wide aperture from surplusshed.com and installed it into a PVC tube, then attached my camera to it (no lens). I used it for solar observation- a few times, the focused light ended up melting the tube, part of the camera, and anything else it came in contact with.
But it makes more sense to buy a cheap but decent refractor or reflector unless you are truly invested in DIY. there's a lot of fiddly details to get right to get decent image quality.
This project is fantastic, but you also deserve congrats for the 'Lens Maker'[0].
"If we have a compound optical system made of a series of lenses, mirrors, etc., we can treat each optical element as the layer of a neural network." Kudos.
Really cool. Did you consider using hexagonal lenses? It seems like they would tessellate, while being closer to being circular.
Would it be possible to make it look like the light was coming in at an angle from above and the side like real sunlight?
I've given some thought to this, I agree it's one of the obvious improvements. I think with a refractive design like this one it's difficult, because of the way a lens works. Most other projects like this including commercial ones like CoeLux use a reflective design, and I believe that's partly for this reason.
I’ve seen the video he links at the top of the article, a few years back. They took an old satellite dish, silvered the surface, and put a giant LED where the receiver had been so the light produced was nearly parallel. Otherwise the shadows look wrong.
In his case he sacrificed a doorway or a closet to make a window with “real light”
I was thinking of the same video! Link:
Would moving the box itself help provide that effect? Maybe put it on a track to move throughout the day?
There was a project posted here awhile ago with something similar, but the light was larger and he positioned it outside a fake window with a curtain across it.
Honestly this area is so interesting to me because of how incredibly strongly light (or lack thereof) affects in the winter. It also seems to affect me more strongly than most in regards to sleeping patterns. Too much blue light in the evening and bam, brain refuses to sleep until 2am or later.
So for me the biggest factor missing in these kinds of projects is a dynamic color temperature. While we get that from products similar to apples adaptive lighting, that’s missing in products like this. It seems we can only really have one or the other.
My dream is something like this build but with full adaptive and programmable color temperatures based on time and seasons.
Honestly I want to build something like this but my area of expertise is too far into the software domain, and not very far into the hardware or electrical engineering domain.
This is the reason I decided to use 4000K instead of the more physically accurate 5400K. I picked a less middle of the day color temperature and closer to evening time, basically.
I spent a lot of time looking at LED suppliers and there's quite a range of options in terms of color temperature. Some manufacturers even have 2 color temps on the same LED package, meaning you can sort of do what you describe by mixing two light sources at a distance less than a millimeter.
> Honestly I want to build something like this but my area of expertise is too far into the software domain, and not very far into the hardware or electrical engineering domain.
That was me last year before starting this project! You'd be surprised what you can achieve with time and effort!
Thanks for your response, that’s actually very encouraging. I e definitely spent a lot of time looking at LED suppliers too.
Currently my favorite bulbs are the ones that are as you describe- two LEDs, one as high as 6500k and one as low as 2200k and it mixes depending on the state of the dinner. Automateable!
Start small and this goal will give you a nice direction.
Don't think you'll be able to do this in 6 months or a year but if you had started doing little electronics/hardware projects 10 years ago, you'd be ready now.
Very cool! I'd be curious to see an HDR version of it using bracketed exposures--it might give a better sense of how it actually looks in person. It seems really bright in the photos, so the shortest exposure would probably need to be very low to capture a good dynamic range for the HDR.
Are you aware of Brilliant Light Power and their Suncell (R)?
See https://brilliantlightpower.com/plasma-video/
and scroll down to the
February 10, 2023 COMMERCIAL SUNCELL® INITIAL SHAKEDOWN
video.
From the first videos, I thought this as a one meter square, or larger.
500 W of luminosity in such a small package, as it turns out, seems close to a thermal limit, even with 90+% efficiency.
how does this compare with heat dissipated per square cm when you compare with desktop CPUs?
I've just mounted tons of full spectrum LEDs in my home office. Off the shelf, fairly cheap, easy to replace. My plants like it, except for the Goeppertias that keep dying on me
I would be more interested in making a SUNSET sunlight vs regular sunlight. That would be actually amazing.
This is a great build and report. Even though you don't have great photo gear, you should try capturing a picture of steam in the light (as DIY Perks did).
That's a great suggestion, thanks! I'll give it a try. It already works with dust quite well though, hehe.
Toyed with making lights from loose smd LEDs too. Hit thermal issues pretty fast unfortunately. They get really hot when you drive them hard
Is there any reasonable tool to design fresnel lens for this? They'd be slightly more compact.
Great project! Instead of routing ground traces, I would recommend to use a ground plane on the bottom layer of the PCB
He's doing it wrong, the obvious approach being to extract sunbeams from cucumbers!
:-)
Nice project. A few miscellaneous notes:
> Kinda cool that you can see a lens flare effect in the shape of the lens grid array.
A lens flare is just a copy of the scene you are photographing, but strongly attenuated in brightness, and possibly rotated 180°.
> 100,000 lux
Your notation is correct, and there are other ways to write it. The SI unit "lux" has the symbol "lx". Your quantity can also be written as 100 kilolux or 100 klx.
Sunrise alarm clock lamps are a really great way to wake up, especially if you have a larger room.
Might be useful for psoriasis treatment?
Idiotic question, but can you have an "angled mode" that lets the godray travel during the day, following the real suns position, given the location and mounting direction of the light?
Yea, I can relate. I tried making an artificial Big Bang at home.
But my neighbors kept complaining 8-/
Haters!
Probably the same people that keep flagging comments on the articles I'm interested in...
