3 ms·

Could we just place a lens of some sort on pre existing led street lights to decrease the amount of blue light emitted?

chiefofgxbxl 10y ago
A filter to block out a bit of the excess blue light? This would reduce the effectiveness of the light output though, unless you amped up the output to raise all of the colors and then selectively suppressed the blue to help balance it out. Then this would require extra energy, which defeats the purpose of using LEDs to save energy.
- joshkpeterson 10y ago
  You can just use a different color of LED. Honestly people in Seattle, where these LED lamps were first piloted, have been raising these concerns for at least 4 years. This is the product of some combination of bad design, a lack of user-centered thinking at the utilities, and less than ideal incentives. For example, daylight led's were touted as making it easier to identify cars involved in criminal activity because you can see the color of the vehicle more easily. But how many times has this actually made the difference in solving a crime?
  - analog31 10y ago
    One of the many hats that I wear at my day job is optics designer. An issue is that the white LED is a particular thing. It's a blue LED coated with a phosphor that absorbs some of the blue light, re-emits it at a broad range of longer wavelengths, while also passing some of the remaining blue light through. The blue is special -- 473 nanometers -- due to the solid state physics of the semiconductor. There is indeed an ongoing search for white LED designs that produce less glaring blue without sacrificing overall efficiency, but counterintuitively it's a hard design problem. People also want warmer light in their houses, so the problem is not limited to street lighting. The safety regulations have a special place in hell for "retinal blue" light. As it turns out every wavelength from UV into the IR has a set of weighting functions for estimating the overall hazard exposure. It's possibly a rare example of a truly science based regulation.
    - joshkpeterson 10y ago
      Is it currently feasible to make LED's at that brightness that are closer to the old yellow-orange lamps?
      - analog31 10y ago
        That's the 64 dollar question. At present, they exist but are less efficient.
  - losteric 10y ago
    Really? Who complains about the new lights? I live in Seattle and I really like the new lights, they're way better than the dingy orange HPS lights. It's easier for my eyes to adjust when walking out of a bright apartment, and I can see more details. Anecdotally, I've also seen fewer vagrant types in the newly lit areas.
    - stephengillie 10y ago
      Also a Seattle resident. Who's complaining? Neither the Times, PI, nor Real Change have mentioned this recently. I've been enjoying the brighter streets at night.
mirimir 10y ago
How about an add-on cover with "phosphor to downconvert the blue LED spike to warmer colors" [thanks, nickhalfasleep]?

A filter to block out a bit of the excess blue light? This would reduce the effectiveness of the light output though, unless you amped up the output to raise all of the colors and then selectively suppressed the blue to help balance it out. Then this would require extra energy, which defeats the purpose of using LEDs to save energy.

joshkpeterson 10y ago
You can just use a different color of LED. Honestly people in Seattle, where these LED lamps were first piloted, have been raising these concerns for at least 4 years. This is the product of some combination of bad design, a lack of user-centered thinking at the utilities, and less than ideal incentives. For example, daylight led's were touted as making it easier to identify cars involved in criminal activity because you can see the color of the vehicle more easily. But how many times has this actually made the difference in solving a crime?
- analog31 10y ago
  One of the many hats that I wear at my day job is optics designer. An issue is that the white LED is a particular thing. It's a blue LED coated with a phosphor that absorbs some of the blue light, re-emits it at a broad range of longer wavelengths, while also passing some of the remaining blue light through. The blue is special -- 473 nanometers -- due to the solid state physics of the semiconductor. There is indeed an ongoing search for white LED designs that produce less glaring blue without sacrificing overall efficiency, but counterintuitively it's a hard design problem. People also want warmer light in their houses, so the problem is not limited to street lighting. The safety regulations have a special place in hell for "retinal blue" light. As it turns out every wavelength from UV into the IR has a set of weighting functions for estimating the overall hazard exposure. It's possibly a rare example of a truly science based regulation.
  - joshkpeterson 10y ago
    Is it currently feasible to make LED's at that brightness that are closer to the old yellow-orange lamps?
    - analog31 10y ago
      That's the 64 dollar question. At present, they exist but are less efficient.
- losteric 10y ago
  Really? Who complains about the new lights? I live in Seattle and I really like the new lights, they're way better than the dingy orange HPS lights. It's easier for my eyes to adjust when walking out of a bright apartment, and I can see more details. Anecdotally, I've also seen fewer vagrant types in the newly lit areas.
  - stephengillie 10y ago
    Also a Seattle resident. Who's complaining? Neither the Times, PI, nor Real Change have mentioned this recently. I've been enjoying the brighter streets at night.

mirimir 10y ago

How about an add-on cover with "phosphor to downconvert the blue LED spike to warmer colors" [thanks, nickhalfasleep]?