Building an artificial sun that looks realistic [video] (opens in new tab)

Spaceships? I can imagine these things in Alaska:

https://en.wikipedia.org/wiki/Whittier,_Alaska

> Whittier is a city at the head of the Passage Canal in the U.S. state of Alaska, about 58 miles (93 km) southeast of Anchorage.[6] The city is within the Chugach Census Area, one of the two entities established in 2019 when the former Valdez–Cordova Census Area was dissolved.[7] At the 2010 census the population was 220, up from 182 in 2000. The 2018 estimate was 205 people, almost all of whom live in a single building, the Begich Towers.

https://en.wikipedia.org/wiki/Begich_Towers

> The Begich Towers Condominium is a building in the small city of Whittier, Alaska. The structure is notable for operating like a small-scale arcology, being the residence for nearly the entire population of the city, as well as containing many of its public facilities. This has earned Whittier the nickname of a "town under one roof".

Riding the coattails of your comment to ask the hive mind: any reason I shouldn't try to build the simpler version from the tutorial using a more powerful (100W) LED from Amazon?

https://www.amazon.com/dp/B07T8RDF8F

Might not be as awesome as a $60k CoeLux, but for 1000x less cost, maybe it's worth a shot?

(Edit: come to think of it, with an 8x10 fresnel lens, it might be way too bright for the size.)

Especially if they emit the UVB light we need for Vit D production

I looked into it for a client's commercial building. $40k each for parts only.

I did something similar to this but was turned away from using random bulbs off of Amazon since most of them lied about their product performance (advertising peak wattage of all the LEDs and then not driving them at max power), safety certifications (fake UL and ETL markings), and in several cases I could not even find valid business licenses where the companies claimed to be incorporated. I need light for the darkness of winter but not at the expense of burning down the house.

Instead, I ended up buying a string light[0] and a box of 1600lm daylight LED bulbs[1]. Installation sucks, but once the whole thing is up, it’s nice that the light is distributed throughout the room instead of coming from a single point source. It was (at least at the time) cheaper than buying corn lights—and as a bonus, you can swap back the bulbs that come with the string light for party lighting.

[0] https://www.costco.com/feit-electric-48'-led-filament-string...

[1] https://www.costco.com/feit-electric-led-100w-replacement-br...

I actually purchased the 35,000 lumen corn bulb mentioned in the post you linked to. It's actually really big and awkward to place and has kind of a loud fan. Currently I have it propped in a corner since it's too heavy to be held by anything that I have to support it. But it will light up a bedroom just as much as a window of sun will. It doesn't look entirely like sunlight, but for the price, it does an adequate job.

Seconding this, although I only bought one giant 14k lumen corn cob, since I didn't have a good spot to put the second. Anecdotally, they've been great at staving off my usual post-lunch slump. Right around the same time as I got it, though, I started waking up much earlier naturally, without an alarm clock (shifting from ~9AM natural wake up to more like ~6AM). I'm careful about turning the corncob off no later than 6PM, and the earlier wake up time might be unrelated, but I was wondering if others had experienced a similar phenomenon with extended, consistent exposure to super bright lights during the day.

I was looking into this last year, but couldn't really find anything similar here in Sweden (or anywhere in the EU). I wonder if there are some regulation here banning ultra high lumen bulbs? The closest match have been on semi-sketchy sites, where they've been ≈ 300 euro for 10k lumen...

How expensive are they in the US?

The main issue is the blue scattering. If you can get away with pre-scattering the light before it hits the dish adding an IR lamp is no issue since you're using a parabolic mirror which has no diffraction. I have no idea if it 'feels' right doing that though.

For full immersion you would also want a number of different light sources since leds are have very narrow spectra.

Yes, patio heaters are very cheap. Such an infrared emitter would have been a very easy addition to this project, at the cost of doubling the power draw.

He has a video of that project as well. It's not as good as this version but can look very nice.

https://youtu.be/8JrqH2oOTK4

Check out Edmund Optics. They do have precision fresnels but they're tiny.

The lenses I've seen at EO have focal lengths that aren't much shorter than the side length---20cm for 25cm sheets. I'm pretty sure this is a limitation on the refractive index plus maybe the precision required for steep incidence angles.

I thought there was some people building things similar to this (not as bright) and they were using lenses from the front of LCD TVs. But I may be remembering the details wrong.

I wonder if you could use a spotlight like a bit like this: https://www.amazon.com/Primelux-8-inch-14400-Lumens-Driving/... to get the intensity and parallel rays.

There is also severe lens flare to deal with for fresnel lenses.

Interestingly, you can DIY that too: http://www.dr-iguana.com/prj_FlatPackMirror/index.html

And I think they really could be a good option. Unlike the lenses, there would be no chromatic aberration with a reflector, right? Plus, you can set the focal length to whatever you want (taking practicality into account of course).

I might have to try it out...

I wonder this as well, perhaps it's a problem related to manufacturing shrinking sized concentric steps?

If my understanding is correct, fresnel lenses effectively operate as a larger lense surface by concentrating light with flat or curved steps getting smaller in size packed towards the core.

Do you mean just the lens? There's one in each of those old school overhead transparency projectors. Those should be easy to find.

https://www.bhphotovideo.com/c/product/592006-REG/Dry_Lam_50...

Sounds like something you could 3D print.

I personally hate sunlight for indoor activity. It's just too intense for anything involves vision, reading, writing, looking at screen, etc.

Do they make "directional" or "angled" Fresnel lenses?

Because you also really want the light to come out of the vertical window at something like a 45° angle downwards.

The physics of it should be fine, I've just never heard of them being manufactured.

And then just add a translucent blue diffusing layer on top.

It seems highly commercializable.

Also I think those are sodium lights. More or less a single wavelength, hence the monochrome (yellow and black) look. Just about as far opposite to daylight as you can get!

It was a semicircle against a mirrored ceiling which is a neat trick to double the effect. People naturally lay on the floor like being on a beach and saw themselves reflected back way overhead.

Yes that's exactly what I thought of seeing this! It was so miserably cold and sleeting the day I went and inside it felt like an oasis. Everyone lying on the floor basking in front of that giant sun.

Ah, I have fond memories of that, a favourite for me too. I wish it was a permanent exhibit. His exhibition there last year was just great too with lots of light used in different ways.

It looks amazing already, however another fun thing to do will be to vary the light intensity over time to make it more like the sun.

Coelux has one: https://www.coelux.com/en/news/coelux-moon-at-euroluce2017-2...

Just change the color temperature and brightness.

The Yuji LEDs he has are very high CRI (95+) and very expensive. Not sure what exactly metal halide CRI is, but Googling it seems its from 60-90.

I'm looking for a warm glow for my dining room.

Wdym with "250-400 ways" is that a brand?

Just take vitamin d.

The reason that people are deficient is because they don't take enough - the US RDA was shown to be 10x too low, due to an arithmetic error in an ancient paper.

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

Other than the CoeLux I haven't seen anything like it

It certainly won’t amplify anything since the only powered component is the LED.

It might concentrate RF at the focus to some degree, but only if you put your head right at the focus, and even then it’s almost certainly orders of magnitude less exposure than using a cell phone.

The focal point of any such amplification would be where the LED is mounted...so I think it would be a non-issue

The 3M ‘chrome’ vinyl wrap is conductive.

He has an older video on doing just that: https://www.youtube.com/watch?v=8JrqH2oOTK4

Agreed if you just took some of the parts where he has the window setup, you'd have a hard time telling the difference.

Taking it as given he's pre-armed to be enthusiastic, he projects a sense the experiential outcome is good:

Yes, he's biassed. No, that doesn't mean he was lying. The realism is about the subjective experience. If you went into the room, you probably would feel "this isn't bad" before you went to Meh.

Yeah, but it show how you can do it by yourself and not spend 30k on manufactured one.