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.
