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I tried making artificial sunlight at home

victorpoughon.fr

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Re: I tried making artificial sunlight at home

#41

Post by alejohausner »

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.

Re: I tried making artificial sunlight at home

#42

Post by fouronnes3 »

alejohausner wrote: post #41

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 fa…

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).

Re: I tried making artificial sunlight at home

#43

Post by foobarian »

Const-me wrote: post #35
brcmthrowaway wrote: post #25

Earlier quoted context omitted.

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.

Re: I tried making artificial sunlight at home

#44

Post by polishdude20 »

sberens wrote: post #39

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/

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

Re: I tried making artificial sunlight at home

#46

Post by crazygringo »

alejohausner wrote: post #41

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 fa…

> 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?

Re: I tried making artificial sunlight at home

#47

Post by dan-robertson »

sheepscreek wrote: post #34
jclarkcom wrote: post #19

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 s…

“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.

Re: I tried making artificial sunlight at home

#48

Post by vincekerrazzi »

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.

Re: I tried making artificial sunlight at home

#49

Post by jclarkcom »

klysm wrote: post #36
jclarkcom wrote: post #19

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 s…

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
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