Strange LED Streetlamps - Page 1
Forum section: electronics / general

author: Cyberdragon
author_rank: Super Contributor
timestamp: March 11, 2021, 08:12:53 am
content: I saw some strange yet beautiful LED streetlamp bulbs in Baltimore the other day. Some sort of art deco/futuristic styled ones. I don't have photos but I can describe them. Their construction is as follows:-shiny metal base with a pattern in it (I assume a heatsink), the pattern is similar to gas/oil burner bases-3-4 cylindrical light pipe diffusers (depending on bulb wattage I again assume) with concave tops like giant strawhat LEDs jutting up out of the base-color temp: unknown (seen during the day when off)Has anyone seen anything like this or know what model or brand they would be?

author: Cyberdragon
author_rank: Super Contributor
timestamp: March 11, 2021, 09:00:31 am
content: From what I have found, they were probably installed recently during their LED lighting project.https://transportation.baltimorecity.gov/bmorebrightThe fixtures don't look like anything they've shown. They appear to be retrofit bulbs. I doubt I'll be able to see them on Google maps either as it would have to be a very recent streetveiw.

author: Cyberdragon
author_rank: Super Contributor
timestamp: March 11, 2021, 11:14:18 am
content: After finding a bunch of lights still not retrofitted (digging around on streetview) where I remember them to be, I found some that had been already (photos must have been taken during installation, they were all like this when I was there).Here's one of the specimins...identify.

author: Cyberdragon
author_rank: Super Contributor
timestamp: March 11, 2021, 11:36:15 am
content: I explored around in the recent...or maybe not, images. I don't even know if these are LED anymore, I think they might be sodium, or at least a mix. The crystal things are just diffusers, I found one stuck lit in daytime and they are lit from the top. Also, you can see some weird junk going on up top on some that does not look LED.So far found on Portland St, Washington Blvd, and Emory St.

author: Fraser
author_rank: Super Contributor
timestamp: March 11, 2021, 11:44:06 am
content: Looks like LED light pipes illuminating a top mounted light reflector. Commonly used to create a downward light spread and reduce light pollution. The light pipes may glow in darkness like a ‘candle’ or gas mantel but they will not emit significant uncontrolled light off their sides so the light distribution remains controlled by the reflector above them. The reflectors shape and angle distaste’s the reflected light coverage characteristics.Simple physics and opticsFraser

author: Fraser
author_rank: Super Contributor
timestamp: March 11, 2021, 11:46:18 am
content: https://vcclite.com/light-pipe-design-guide/Fraser

author: Cyberdragon
author_rank: Super Contributor
timestamp: March 11, 2021, 11:58:47 am
content: Yeah, those are reflectors at the top (that one looks siliconed in though). I assumed that's how they worked at first but when I saw virtually 0 side light bleed I was like. I'm used to lightpipes being those cheap plastic things in consumer goods that leak like crazy.Though if they are custom jobs, we'll never know who made them.

author: Fraser
author_rank: Super Contributor
timestamp: March 11, 2021, 12:03:56 pm
content: I have been searching for the combined LED and light pipe lamps and failed to find them. I wonder if the light pipes actually clip onto a relatively standard LED lamp ? The reflectors can be made with various finishes to meet the specific need of the location. Mirrored reflectors create a powerful downlight but sometimes a white reflector is used or even a combination of reflector and diffuser is employed to create ‘soft light’ that is not so harsh and blurs the edges of the light ‘pool’ beneath the fitting.Fraser

author: Fraser
author_rank: Super Contributor
timestamp: March 11, 2021, 12:08:34 pm
content: In the UK we still have some gas mantel street lights that are being preserved as a view of times pasthttps://www.theguardian.com/culture/2015/dec/25/londons-last-gas-street-lampsInterestingly the old shape of light had positive effects with regard to light pollution. If the light source is high in the top of the lamp it generates plenty of side light plus down light but reduces up light significantly.Fraser

author: mzzj
author_rank: Super Contributor
timestamp: March 11, 2021, 01:04:22 pm
content: Speaking of strange led streetlights:Some street lights(Nice, France) separate to 3 different colors when you pan your head/eyes enough fast.Talking about really disturbing effect when the street light becomes rainbow-colored stripes.

author: Sal Ammoniac
author_rank: Super Contributor
timestamp: March 11, 2021, 08:30:56 pm
content: LED streetlamps are evil. At least with the old mercury and sodium streetlamps we could filter out their narrowband spectra, but LEDs are wideband and that makes them nearly impossible to filter.

author: Zero999
author_rank: Super Contributor
timestamp: March 11, 2021, 10:02:37 pm
content: Quote from: Sal Ammoniac on March 11, 2021, 08:30:56 pmIt would be very easy to make an LED streetlamp with a narrow bandwidth. Most LEDs are inherently monochromatic light sources. White LEDs are broadband because they're just blue chips, with a wideband phosphor.

author: Sal Ammoniac
author_rank: Super Contributor
timestamp: March 12, 2021, 03:08:40 am
content: Yeah, sure, it's easy to make a monoband LED streetlight using red or amber LEDs, but I just don't see that happening. People like the neutral white color of current LED streetlamps and I can't see anyone wanting to go to monochrome lights, except maybe in cities near major observatories. The rest of us are going to be out of luck and will have to deal with increasing levels of light pollution as LED lighting becomes more common.