What I'm trying to achieve is lighting a bit like in these "Artificial Skylight" concepts: https://architizer.com/blog/practice/materials/let-there-be-... They claim their technology is about "Rayleigh scattering" but I think that's mostly marketing mumbo jumbo. Sure that might add a bit of diffuse blue but their main secret, I would bet, is parallel rays which explains why their fixtures require so much space above the ceiling to get around conservation of etendue. The effect of parallel rays and sharp shadows are definitely represented in their example pictures.

I’ve installed 4 similar skylight lamps to the basement. Bought them on Amazon for 700$ each (had to replace 1 because it had uneven light). They make basement light much closer to ourdoor light and made basement very cozy and comfortable. I had depth space in the ceiling, but width of the lamp didn’t fit between joists - so could not push lamp all the way at the ceiling level. End up building nice boxing around lamp. So it was medium complexity project with great result.

I'd wager they're pretty good. If you can leverage a parabolic reflector at a light's focal length, you can get them to collimate in a way that approximates the sun by appearing to be pinned near-infinitely far away. The reflector is generally what takes up the space, but it's necessary(ish) -- you could approximate the effect by using a fresnel lens at the light's focal length, but it yields a smaller light with rainbowing effects.

[This video](https://www.youtube.com/watch?v=6bqBsHSwPgw&t=843s) does a good job of showing how to make your own, as well as illustrating how good the effect is, while also demonstrating why space-hog implementations are likely to yield good results and slimmer ones not.

Reminds me of this old dyi video about using decommissioned led monitors to create light boxes with parallel rays to emulate sunlight: https://www.youtube.com/watch?v=8JrqH2oOTK4

I've been wondering for a while now if our indoor lighting is too dim. Even in the shade during midday you're looking at 20,000 lux. Overcast days look dark and dreary and they're on the 1000-2000 lux range.

Meanwhile home lighting is well below the 500 lux range, if not even in the 100-200.

I even suspect that the current near-sightedness epidemic is caused by people spending too much time in dim lighting. Maybe if our indoor lighting was brighter our eyesight would not adapt to become near-sighted as much.

Yeah there's definitely that aspect too. Though nowadays, led lighting is so efficient that you can get a lot of brightness on reasonable wattage.

That's not enough for the light to feel natural though, you also have to have the parallel rays. And then there's also challenges with brighter lighting to set it up so it's not uncomfortably bright in your field of view or blinding you :-)

> I even suspect that the current near-sightedness epidemic is caused by people spending too much time in dim lighting. Maybe if our indoor lighting was brighter our eyesight would not adapt to become near-sighted as much.

It's not that eyes are adapting to low light so much as the fact that exposure to 10k lux stimulates the release of neurotransmitters which prevent the eye from growing too quickly. Last I checked, the recommendation is for children to spend 2+ hours per day outdoors in sunlight. Morning and evening aren't sufficiently lit so it really comes down to school and after-school care scheduling enough outdoors time.