Boxed Sun

Boxed Sun makes sunlight even more optional.

Overview

The goal of this project is to create an artificial skylight. As hackers we often like working in the dark, but our crepuscularity is most pure when it's a choice rather than an inevitability, therefore we should always have the option to experience daylight [even if we choose not to].

Additional benefits:

• Having a distant star simulator would be a pretty neat addition to the space
• This could be useful to international visitors experiencing jetlag
• Improved lighting

Goal

Produce a light source that is as indistinguishable from a real skylight as possible.

Stretch goals:

• Make the "time of day", "season", and/or the "location" adjustable parameters (more on this below)
• Synchronize the above parameters with the supposed "outdoors"
• Make multiple artificial skylights, synchronized to produce the effect of one star (or multiple, for when we have Trisolaran guests)
• Publish it as an open source hardware project for others to enjoy
• Design, produce, and/or sell a kit to make it easier for others to enjoy

Modulo marketing, it looks like this has already been done commercially [and therefore should be possible'ish]. Moreover, there exists a YouTube video detailing the construction of a DIY version.

Background

It would seem that [at least] two conditions will need to be met in order for the skylight to look convincing:

• Light collimation
• Rayleigh scattering

Collimated light creates the effect of a distant light source. This should be possible using a lens or a reflector:

While a lens of this size may not be practical and a Fresnel lens will produce unwanted distortions, a parabolic reflector can be created by mirror'izing a parabolic dish, as seen in the video above.

Rayleigh scattering is what makes the sky blue and, in scattering some of the blue light, makes the Sun's light appear "warmer". As the Sun's angle changes (with the time of day, the season, one's location on Earth), its rays' path through the atmosphere varies in length, and therefore the amount of scattering varies, resulting in a color change.

The engineers at CoeLux appear to have achieved this with some sort of film containing nanoparticles; this seems worth looking into and perhaps recreating [or purchasing, if that's an option]. In the video above, a similar effect is achieved using a volume of soapy water; this has some advantages as well as some disadvantages.

Plan

• Prototype
  • First, we should create a small proof of concept
  • The aperture should be at least 10E-2 m^2 to properly demonstrate the effect (why that specific size? I don't know, just a gut feeling)
  • Assuming we'll need want something like 10E5 lux to approximate the Sun's brightness, we'll need to use a light source that produces at least 10E3 lumens (10E5 lux = (10E3 / 10E-2) lumens/m^2).
  • For this phase of the project, we could just make a smaller version of what's described in the video. It might be nice to avoid having to use soapy water to simulate the scattering, so we can take this opportunity to explore other options, but if we can't figure out a more elegant solution, soapy water it is!
• Pilot
  • Assuming a convincing prototype is produced, we may want to spec out a larger unit
  • Something on the order of 1 m^2 feels like it could be pretty impressive
  • Based on the calculation above, this would require a 10E5 lumens light source, which will draw a lot of power and produce a lot of heat
• Profit
  • ...haha just kidding, let's see if we can get a prototype working

Notes

• Adjustable "Sun angle"
  • This would require varying both the direction of the collimated light as well as the simulated path length of the light through our artificial "atmosphere"
  • The former could be accomplished by rotating the mechanism mechanically
  • To achieve the latter, if we are using a fluid to simulate scattering, we may be able to change the shape of the filter, pumping liquid in and out as necessary
  • Alternatively, we may be able to create a 3D filter which we could rotate to change the length of the path taken through the substance, and/or use a clever arrangement of mirrors to reflect the light through said the material several times
• Rayleigh scattering
  • Using alumina particles: https://pubmed.ncbi.nlm.nih.gov/24058661/
  • We may be able to use an optically transparent material other than water, such as an oil
  • We could also use a solid material, such as glass, a polymer, silicone, etc.
• Heat dissipation
  • On the one hand, a large version of this is going to produce a lot of heat
  • On the other hand, Noisebridge has been uncomfortably cold lately, so maybe we could harness the "waste" heat to help defrost our hackers' fingers
  • Using liquid cooling to feed a heated floor seems just impractical enough to mention, but we could probably just blow air over the radiator and duct that air toward said hackers
• Acknowledgements
  • Thank you User: Murph for workshopping these ideas and for sharing much of the information above
  • Thank you Noisebridge Illuminati for entertaining [and possibly bankrolling] these ideas
  • Thank you dear excellent human for reading [and participating if you so choose]!