Question about the new LED street lighting

[davelew.livejournal.com]

This is a long shot, but there's enough random information on this community that I thought somebody might be able to help.

The city of Somerville is switching from old sodium vapor street lights to new, more energy efficient LED street lights. That's great and I support it, it's good for the environment and for the city's finances. The problem is with my telescope. I have a filter for my telescope that cuts out light pollution from old-style lights, by blocking light at precisely the wavelengths of the emissions spectrum of sodium atoms. Unfortunately, that filter does nothing for the new LED lights. It's nice to have a filter for urban astronomy if you're looking at anything dimmer than the moon, and I don't know what filter(s) to get.

So, here's my random question: Does anybody know the emissions spectrum of Somerville's new LED lights? Or even a single particular wavelength that they don't emit? I'd even be happy with a model number so that I could contact the manufacturer.

Comments

[xuth.livejournal.com]

LEDs actually run much cooler than most other lighting technologies, but they fail at much lower temperatures as well. Sodium lights do have circuitry in them that fail over time as do the bulbs. Look at http://en.wikipedia.org/wiki/Sodium-vapor_lamp#End_of_life to see their bulb failure state which is typically somewhere around 20,000 hours or about 4-5 years of operation. I have no idea how long the sodium lamp circuitry lasts but I do know that ballasts die over time.

LEDs themselves can last 5+ times this so you're more likely to be limited by the lifetime of any circuitry you build your lamps on. Most of the individual components can last almost indefinitely, it's typically any of the hundreds of connections that fail.

[perspicuity.livejournal.com]

much cooler in comparison is true, but they still run hot enough you can't hold or touch one after it's been on a bit - even flashlights. there's this myth that LEDs run oh so cool, like fluorescents might but even those guys get hot. makes sense though, pump in a lot of power, they get toasty. very few lightning technologies run cool.

as long as we're not getting bad components (capacitor rot), and they are surge protected (line power step down to LED power, regulation, they won't need some of the things flashlights do...), things should be golden for a long time. "should be".

CFLs have taught me to be very skeptical of line voltage powered drop in replacements for Edison bulbs. i'm glad they are going out of favor.

LEDs are the future thus far. they even lend themselves to light guides and lenses as well.

#

[xuth.livejournal.com]

As far as heat, it's really just a matter of efficiency and surface area. The higher the efficiency the less extra heat you create for the amount of light you produce. Until recently good fluorescent and good LED lighting were about equivalent (with different trade-offs) so they generated the same amount of waste heat. But since a fluorescent light has a larger surface area than a similar fixture of any other lighting type, there will be a lower temperature. LEDs are lower temperature than incandescents for the same output because they are more efficient.