Re-creating Disney's sodium vapor process [video] • Hacker News Board

Re: Re-creating Disney's sodium vapor process [video]

#111

Post by jayknight » Thu, Apr 11, 2024, 2:27 PM UTC

dylukes wrote: post #109

jayknight wrote: post #81

Earlier quoted context omitted.

On a trip to San Diego, I ran to a grocery store one night, and had a hard time finding my car because of light like that, and I couldn't tell what any of the colors were. It's that still common out west?

San Diego is near the Palomar Observatory and Mount Laguna observatory (see map [1]). The observatory as well as environmental concerns of bright lighting at night messing with wildlife is why San Diego in most zones at night uses what appear to be Low Pressure Sodium (LPS) lighting. See also [2] for the current code. However, over time these LPS streetlights started to be replaced by Induction lighting. And as of 20…

Thanks, this is way more interesting than I thought!

Re: Re-creating Disney's sodium vapor process [video]

#112

Post by delfinom » Sat, Apr 13, 2024, 3:17 PM UTC

erincollective wrote: post #107

is this what they're doing here but with polarization instead of wavelength? https://patents.google.com/patent/US20070247553A1/en

Yes, thankfully the patent claims are specific with polarization so the method with sodium vapor here is safe.

Re: Re-creating Disney's sodium vapor process [video]

#113

Post by delfinom » Sat, Apr 13, 2024, 3:19 PM UTC

Tally wrote: post #97

rerdavies wrote: post #61

Earlier quoted context omitted.

Presumably, the exotic part of the beamsplitter is that the dichroic filter must be a bandpass filter with a very narrow passband around 596nm. Yours is a high-pass filter, which wouldn't work for this application.

I mean, a bit more searching did seem to turn up a few notch beamsplitters near the required frequency (not quite the same frequency though) I am wondering if part of the reason that finding these at the frequency of sodium vapour lamps is partly due to those lights no longer being common. Or perhaps that those just aren't frequencies common to laser optics, which seems like the biggest market for these kinds of devi…

589mm notch filters are readily available

https://www.edmundoptics.com/p/589nm-cwl-125mm-dia-hard-coat...

Re: Re-creating Disney's sodium vapor process [video]

#114

Post by hondo77 » Thu, Apr 18, 2024, 3:54 PM UTC

djmips wrote: post #101

hondo77 wrote: post #88

Earlier quoted context omitted.

It's not that they forgot how the multiplane worked. They understood it...in theory. However, they were quirky beasts and it was knowledge of those quirks that was lost. Like getting an old car to run--most people these days don't know about pumping the gas pedal to keep it running.

Pumping to start the car, to prime the carb but never heard of the keep it running part unless you been needing to keep the revs higher until it warms up? But then you don't need to pump, just hold it.

Keeping a 1966 Ford Galaxy running on a cold day could be challenging. You could warm it up for a while but at some point you'd need to get moving and the pumping to get it moving would start. Then came stop lights--couldn't keep the engine revving while slowing and at the light (well, you could shift into neutral but that was more of a pain than it was worth). Then pump to get it moving again. This was all in the city--if you got to go on the freeway or a country road that morning, things were much easier. It did warm up eventually, of course.