It's actually not something covert. It's a manufacturing quality problem wherein components fail and the units have to be replaced with better quality devices. However this purple light problem is real and is widespread in some communities.
If it hurts, the lamps may be putting out a lot of ultraviolet. Here's a test: have something that is fluorescent orange. If it appears bright orange at night under the lamp, that's a sure sign this is an LED lamp whose internal phosphor has failed and it lets dangerous UV from the diodes out. (UV causes fluorescent materials to glow and actually emit light.)
A white light LED works like this: the LED actually puts out ultraviolet at the core. The LED converts that to white light by having a phosphor coating around the emitter to do that, they operate just like a standard fluorescent tube light. In the street lights with a manufacturing defect, the coating degrades and lets purple and UV out. And that damages eyes.
This may be topnotch Chinese LED quality here, where they are shoddy just to save a penny.
If the light hurts your eyes at night, blueblocker glasses can stop the UV. They will look clear for ordinary light but they block UV wavelengths. Might be useful for a cop on night patrol.
The guy is mostly correct on the cause, degradation of the phosphor (not phosphate though). But he's wrong in that the degradation doesn't turn the LED itself to UV - that is fixed forever by quantum mechanics factors. See #3 below.
ALL white light LEDs start with a UV LED emitter - we do not know how to make LEDs that emit white light themselves. It's a quantum mechanics thing, there is no band gap that gives out pure white light. In other words, the base LED for white light is actually always designed as a UV emitter. That part never changes. (red, green yellow LEDs are different, they give out RGY light from the start, they have no phosphor. Blue LEDs are kind of mutants and close to UV.)
If you look at many LED lights you will see that the unlit COB LED looks yellowish. That is because there are two coatings on the LED itself. One is the bottom layer over the LED chip; it is a light emitter that takes in UV and outputs white light; the top coating over it is yellow to filter out any UV that passes through. In the shitty Chinese LEDs, they make them with bad chemistry for the top layer and it degrades because any UV leakage actually destroys the yellow dye compound over time.
It's actually not something covert. It's a manufacturing quality problem wherein components fail and the units have to be replaced with better quality devices. However this purple light problem is real and is widespread in some communities.
If it hurts, the lamps may be putting out a lot of ultraviolet. Here's a test: have something that is fluorescent orange. If it appears bright orange at night under the lamp, that's a sure sign this is an LED lamp whose internal phosphor has failed and it lets dangerous UV from the diodes out. (UV causes fluorescent materials to glow and actually emit light.)
A white light LED works like this: the LED actually puts out ultraviolet at the core. The LED converts that to white light by having a phosphor coating around the emitter to do that, they operate just like a standard fluorescent tube light. In the street lights with a manufacturing defect, the coating degrades and lets purple and UV out. And that damages eyes.
This may be topnotch Chinese LED quality here, where they are shoddy just to save a penny.
If the light hurts your eyes at night, blueblocker glasses can stop the UV. They will look clear for ordinary light but they block UV wavelengths. Might be useful for a cop on night patrol.
You actually think damaged lights begin to emit UV light?
Give me one example of your absurd statement, please. One. Single. Example.
Please.
I actually have some respect for you, so I will not give a snarky reply. Here's my background and indeed, one example:
The guy is mostly correct on the cause, degradation of the phosphor (not phosphate though). But he's wrong in that the degradation doesn't turn the LED itself to UV - that is fixed forever by quantum mechanics factors. See #3 below.