from Hacker News

Building an artificial sun that looks realistic [video]

by julvo on 11/3/20, 10:39 PM with 123 comments

• by rococode on 11/3/20, 10:50 PM

  In a sci-fi future where people are making long journeys on spaceships I can imagine rooms decked out with these to mimic a natural day/night cycle and outdoor spaces.

  I remember first seeing lights like these a couple years back before from CoeLux (https://www.coelux.com), iirc theirs are very expensive though. Awesome that this guy managed to DIY one!

• by vimota on 11/3/20, 11:51 PM

  If you're too lazy to build something like this out but like the idea I highly recommend bright LED lighting for the day (explained here: https://www.benkuhn.net/lux/). I bought two ~7000 lumens LED corn bulbs and have noticed a huge shift in energy levels from having a brightly-lit room in dark PNW days. I put together a bunch of resources when I was researching buying some here: https://www.notion.so/vimota/LED-World-fce39f79710b42708b92a...

• by bukka on 11/3/20, 11:07 PM

  I'm curious if the lack of heat in the lightrays will ruin the immersion of sunlight? Perhaps couple this with an IR heatlamp to add the real feel of sunrays hitting your skin?

• by linsomniac on 11/4/20, 1:21 AM

  If you have access to a broken LED TV or monitor, or in some cases CFC, you can just buy these. Search for "led panel light", and you can find them in all sorts of sizes.

  I was looking at building one last winter, but on CraigsList people tend to overestimate the worth of a TV with a broken screen. "Awesome 4K TV, paid $1200 3 months ago, just need to replace broken screen, $250." You gotta talk them out of that with a "A new panel costs more than buying the whole TV."

  You can also buy just fresnel lenses on Amazon, but then you gotta build the and line it with foil.

• by filleokus on 11/3/20, 11:06 PM

  I wonder if you could make a better fresnel version, with less chromatic aberration by using a more expensive lens? The parabolic version is cool, but extremely unwieldily...

  Also, are there fresnel lenses with a much shorter focal length? The dream would be to have something like this in a ≈ 10 cm (4 in) thick picture frame hung on the wall...

• by Wistar on 11/4/20, 4:39 AM

  At the risk of making a too simplistic comment, I must say this is an astonishingly great video. Period.

• by ElijahLynn on 11/4/20, 7:11 PM

  Part of me is like, no way I want that, it isn't natural. And the other part is like, yes way I want that, what I do with indoor lighting isn't natural anyways!

• by hinkley on 11/4/20, 4:39 AM

  Why do fresnel reflectors seem to be so hard to find? Seems like they’d be a good option here.

• by VBprogrammer on 11/4/20, 12:15 AM

  Interestingly I posted this 2 days ago but it dropped into the ether.

  Ever since I seen it I've become convinced something similar will be part of a future garden office I'm planning. With a IR panel heater to add the warming effect. I was also wondering about whether UVB could be incorporated by but frankly I'd be too chicken to mess with that.

• by npunt on 11/4/20, 1:21 AM

  Seems like this idea could scale very well with more LEDs of lower wattage, like a local dimming array in TVs. That way

  1. heat would be more evenly distributed reducing the need for large heatsinks

  2. smaller fresnel lenses could be positioned much closer to the light reducing thickness

  3. with a lot of LEDs there'd be a less noticeable grid at the edges of each fresnel lens from chromatic aberration.

  I'd totally buy a 'sunlight window' product like this.

• by Daub on 11/4/20, 8:16 AM

  Anyone familair with this: https://www.tate.org.uk/whats-on/tate-modern/exhibition/unil...

  I saw it at the Tate Gallery. It was one of the most impressive art installations I have ever witnessed.

• by elihu on 11/3/20, 11:45 PM

  A fun modification would be to add a mask directly in front of the LED to change its shape, for instance to mimic the weird crescent shadow effect that many of us saw during the last solar eclipse.

  Some other fun things to do with it would be to point it through some plants in front of a fan to get the filtered-light-through-leaves effect, or to shine it onto moving water.

• by ChuckMcM on 11/4/20, 1:43 AM

  I set something similar to this (didn't to be blue light scattering) for a friend who suffered from SAD (seasonal affective disorder) but had to stay living in Washington state for job reasons. They already had a basement with two sky lights and we used Cree 95 CRI LED stripss with a "2d parabola" (they were re-purposed from a concentrated solar project). It didn't do the 'sun at a distance' effect either, but the light quality was enough to get them through the winter while staying productive.

• by lanius on 11/4/20, 1:29 AM

  How about one for moonlight? My room doesn't have windows, and the nightlights I've tried are too harsh and make it harder to go back to sleep after waking up in the middle of the night.

• by rdtwo on 11/4/20, 1:17 AM

  Leds aren’t a good source of full spectrum light. Metal hallide bulbs are the way to go. 250-400 ways worth has a fantastic warm glow. Bonus points you can grow stuff under them really well

• by elevenoh on 11/3/20, 11:39 PM

  Could indoor or outdoor artificial sun products soon be 'better than sun' (for humans)?

  e.g. has the hormone regulation & vit d synthesis benefits, without the skin damage?

  Because it seems like we're getting there: https://www.sciencedaily.com/releases/2017/09/170913193101.h...

• by aaron695 on 11/4/20, 4:03 AM

  This is an important problem that doesn't get the attention it should.

  Quality high density, and dense time based living is the way forward for the poor to the rich. Be it sleeping downtown in NY city to working suburbs in Hong Kong. Good for efficiency and this is good for mental health.

  This is AR that matters. It's nice work.

• by hsuduebc on 11/4/20, 1:31 AM

  Wow. For some reason I thought it is already product on market with ton of alternatives. Fascinating.

• by ParadisePrime on 11/8/20, 5:38 PM

  He did another video of something similar using diffusers instead from a busted monitor. I wonder if you could add a very thin layer of blue tape on the acrylic layer to achieve a similar effect?

• by Sephr on 11/4/20, 2:03 AM

  Couldn't this potentially dangerously amplify ambient RF if you follow the author's advice of re-using an antenna dish & covering it with a non-conductive reflective vinyl coating?

• by gautamcgoel on 11/5/20, 6:56 PM

  Does anyone here have personal experience with CoeLux? I would like to know 1) how realistic does the light look 2) how much did it cost and 3) how easy was it to install.

• by randyrand on 11/4/20, 4:07 AM

  personally id go with a lot of small LEDs and small reflectors. you could get something pretty thin then.

• by j_walter on 11/3/20, 11:43 PM

  I can't believe it's not the Sun

• by vmception on 11/4/20, 2:18 AM

  ... that looks realistic to a digital camera that doesn't record with high dynamic range?

• by amai on 11/4/20, 1:11 PM

  This is not new. See this video from 2014:

  https://www.youtube.com/watch?v=aJ4TJ4-kkDw

  This light is sold by https://www.coelux.com/. They might also hold the patents on this technology.