DOES ANYONE KNOW WHAT TYPE OF STREETLIGHT THIS IS?

[Elp]

The IDAS D2 filter (and I think following P2) were designed to counteract LED lighting but from all the tests ive read about they don't really make much difference when imaging.

[Luke Newbould]

I found it a major improvement in my area when we finally got switched to LED streetlights! Sure, the light is broadband and thus practically unfilterable, but they are well shielded and not overly bright so I feel that every effort has been made to minimise environmental impact. - some light at night is a necessary evil living here on a main road I guess.

Our old sodium lamps were very poorly designed units - light everywhere! That said, they were probably designed and installed at around the time of the Norman conquest so I can't judge too harshly!

These days I'm covered in bruises on my shins from walking into garden furniture in the dark now during imaging sessions, and I couldn't be happier about it! 😂

[Piero]

57 minutes ago, Luke Newbould said:

I found it a major improvement in my area when we finally got switched to LED streetlights! Sure, the light is broadband and thus practically unfilterable, but they are well shielded and not overly bright so I feel that every effort has been made to minimise environmental impact. - some light at night is a necessary evil living here on a main road I guess.

Our old sodium lamps were very poorly designed units - light everywhere! That said, they were probably designed and installed at around the time of the Norman conquest so I can't judge too harshly!

These days I'm covered in bruises on my shins from walking into garden furniture in the dark now during imaging sessions, and I couldn't be happier about it! 😂

In the village where I live the LED streetlights are much better than the old non-LED ones for the same reason you stated.

Here the LED tend to be warm (a bit orange) but the light is considerably dimmer, much better directed to the street and better shielded. 

BTW, many of the new street lights here seem to be like number [3] shown in a previous post.

[Alan White]

I hope that you have now seen the light in action Paul @paulastro and that it was not an issue.
If you get spill and you need it shielded, a  call to the council responsible may resolve.
The magic words are .... 'Light spill into a Bedroom' only mention Astronomy as a second item.

Let us know how it goes.

I do believe the real light issue is all the private LED's that folks have fitted due to lights off policies and
the general belief (wrongly) that lighting improves security on your home. 

Edited September 14, 2023 by Alan White

[paulastro]

1 hour ago, Alan White said:

I hope that you have now seen the light in action Paul @paulastro and that it was not an issue.
If you get spill and you need it shielded, a  call to the council responsible may resolve.
The magid words are .... 'Light spill into a Bedroom' only mention Astronomy as a second item.

Let us know how it goes.

I do believe the real light issue is all the private LED's that folks have fitted due to lights off policies and
the general belief (wrongly) that lighting improves security on your home. 

Thanks Alan, good advice.  When I went to bed last night the lights hadn't come on, but they haven't finished fitting them yet.  I will post again when they are finished, and when the sky has been clear as well.  I will certainly take your advice if I get 'bedroom light spillage'.  Thanks again. 

 

[ScouseSpaceCadet]

23 hours ago, paulastro said:

Many thanks for that, it's useful information.  The previous lights spilled light everywhere so hopefully they may be an improvement!

These lights spill light everywhere... 🙄

I requested a shield and at the second attempt the council did fit one. A huge improvement - a dull glow spilt sideways rather than so bright, shield your eyes...

You can just about see the shield if you zoom in a bit...

 

I was actually very honest,  explained the light should not be shining horizontally into my property 10m distant and it is ruining my hobby. Although that may just be luck and complaining it's stopping you sleeping might be better... 😉

Edited September 14, 2023 by ScouseSpaceCadet

[maw lod qan]

These are now the trend with new installs over here. I'm also seeing a lot of parking lots retrofitted with them.

Anything that cuts down on the light shining outward has to help some,  but reflected light is still the problem.

What I see at 4am when I go to work is businesses with exterior lighting on the building itself around entrances and on the corners that are still terrible. The sky glow back West from where I live is mostly due to exterior lights on businesses that are closed at night.

[Louis D]

On 14/09/2023 at 06:46, maw lod qan said:

These are now the trend with new installs over here. I'm also seeing a lot of parking lots retrofitted with them.

Anything that cuts down on the light shining outward has to help some,  but reflected light is still the problem.

What I see at 4am when I go to work is businesses with exterior lighting on the building itself around entrances and on the corners that are still terrible. The sky glow back West from where I live is mostly due to exterior lights on businesses that are closed at night.

Exactly.  I've got a car dealership, tollway interchange, and multiple shopping strip-malls that didn't exist 30 years ago when I moved out here.  They are lit up bright as day all night, reflecting light off of everything back into the sky.  Luckily, I'm within a few years of retiring.  I'll be moving to some truly dark skies when I do.

[Louis D]

On 13/09/2023 at 11:50, Mandy D said:

LEDs are monochromatic light sources. They do not produce broad band spectra, which is why we see the big spike at around 430 nm ( blue). To get white light from LEDs there are two common methods, one is tri-colour, with red, green and blue emitters which, when the light is mixed in the correct ratio, produces an approximation to white light. The second method, is the most common and certainly being used in street lights and most other "white" light sources. The blue photons carry high energy (remember E = hν, h is Planck's constant and ν is the frequency associated with the photon), which exceed the level needed to excite fluorescent materials which then release visible photons in a broader band which can be seen rising to the right of the main spike and then tails off at longer wavelengths. The fact that 430 nm LEDs are used, explains the high blue content in the spectrum of "white LEDs".

Thanks for pointing that out.  I was curious why there weren't spikes in the red and green parts of the spectrum if they were using three LEDs to get some semblance of white.  I knew the blue-violet spike was due to an LED, but could not understand the rest of the diagram.

A company named Seoul Semiconductor has an updated, broad spectrum white LED light for more natural (hopefully) indoor lighting.  It, in their words, "combines a purple (sic) emitter with a red, green, and blue (RGB) phosphor mix, as opposed to the conventional white LED that relies on a blue emitter and yellow phosphor."  I think they meant a violet emitter, not purple which would be a combination of red and blue light.  It probably got corrupted in the Korean to English translation.  Here's their comparison image.  Their new LED is in the upper right corner:

Used outdoors, this white LED would be even worse for the HB, OIII, and Swan emission bands than the typical B+YR white LED in the lower left corner.

[paulastro]

Well, I can't believe it.  It was cloudy last night, but I went out anyway to see what the new lights were like. 

No orange light anywhere, and overall it looked clearly darker than it ever had before!  I wondered if perhaps they weren't all on yet, but the lights I could see were on.

The orange glow over the main road in front of the house that is easily seen from round the back where I observe had vanished.

I put my thumb over a single light and no glare was visible leaking round the edges.  Instead of orange the sky was a sort of grey, but you vould see variation in the cloud.  It was drizzling as well, which I thought would have made it worse.

A very unexpected result, can't quite believe it.  The real test will be when there is a clear sky.  Watch this space.

 

[Zermelo]

17 minutes ago, Louis D said:

Thanks for pointing that out.  I was curious why there weren't spikes in the red and green parts of the spectrum if they were using three LEDs to get some semblance of white.  I knew the blue-violet spike was due to an LED, but could not understand the rest of the diagram.

A company named Seoul Semiconductor has an updated, broad spectrum white LED light for more natural (hopefully) indoor lighting.  It, in their words, "combines a purple (sic) emitter with a red, green, and blue (RGB) phosphor mix, as opposed to the conventional white LED that relies on a blue emitter and yellow phosphor."  I think they meant a violet emitter, not purple which would be a combination of red and blue light.  It probably got corrupted in the Korean to English translation.  Here's their comparison image.  Their new LED is in the upper right corner:

Used outdoors, this white LED would be even worse for the HB, OIII, and Swan emission bands than the typical B+YR white LED in the lower left corner.

Yes, the problem is the additional phosphors. As soon as cheap blue LEDs became available, it was possible to create a tri-colour bulb that looked white, but the reflected light from such a source does not render many colours faithfully (ie as sunlight does).

Hence the incorporation of broadband phosphors, using their continuous spectra to produce more natural colours. LED bulbs are now often described with their colour rendering index, in addition to their luminance and colour temperature. I suspect that the market for interior lighting has driven the change, but in surveys people often say that they value "natural" street lighting too.

Since I bought a pocket spectrograph, I've looked at white LEDs (inside and outside) to see if I can find any pure tricolour bulbs, but every one I've tried has had a continuous spectrum.

[Mandy D]

22 minutes ago, Louis D said:

Thanks for pointing that out.  I was curious why there weren't spikes in the red and green parts of the spectrum if they were using three LEDs to get some semblance of white.  I knew the blue-violet spike was due to an LED, but could not understand the rest of the diagram.

A company named Seoul Semiconductor has an updated, broad spectrum white LED light for more natural (hopefully) indoor lighting.  It, in their words, "combines a purple (sic) emitter with a red, green, and blue (RGB) phosphor mix, as opposed to the conventional white LED that relies on a blue emitter and yellow phosphor."  I think they meant a violet emitter, not purple which would be a combination of red and blue light.  It probably got corrupted in the Korean to English translation.  Here's their comparison image.  Their new LED is in the upper right corner:

Used outdoors, this white LED would be even worse for the HB, OIII, and Swan emission bands than the typical B+YR white LED in the lower left corner.

You have to remember that red, green and blue work as primary colours when mixing light because of the way our eyes work, with cone receptors that are individually sensitive to red, green or blue light. The fact that we perceive certain colours when we mix these three so called primary colours does not mean that other colours, such as purple do not exist or have a distinct wavelength associated with them. You certainly would not get purple as a result of mixing red and blue light, in fact, this would produce magenta. I think you are quite right, they should have used the word "violet", though.

Of course, violet light has a shorter wavelength than blue, so it's photon energy is even higher and more capable of inducing fluorescence in suitable materials than blue. In other technologies, such as flourescent tubes and mercury vapour lamps a discharge in a rarefied gas produces strong emissions in the UV part of the spectrum which is then converted to visible light by the phosphors on the inside of the glass envelope. It has been difficult developing semiconductor materials that produce the shortest wavelengths, but I think we now have some producing longer wavelength UV. If I recall correctly, silicon carbide LEDs, the first blue emitters we had, were developed at Sheffield University back in the 1990s. One of my lecturers was involved in this.

[Albir phil]

Yes it's a LED or LEDS (let's end dark skies)

[Gonariu]

Common problem! I think that, for public lightining, a monocromatic light is OK as with the old sodium lights (today I don't know somebody of similar); it's different for a football match at night (you must see the colours of the players' shirts). The light which goes to sky is waste energy unnecessarily too, it's right shielding them, ditto for the luminous signs of the shops: at three in the morning who sees them? And the mass media often talk about climate changes!

Edited September 15, 2023 by Gonariu