They are still used where not needed and Way too bright usually. I have more than once used precisely placed electrical tape to reduce them down to a pinhole or slit.
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I bought a 22 inch Samsung monitor in 2007 and was annoyed as hell with the extremely bright blue LED under the power button. I never knew untill now why it was there. I just thought it was bad design. I always put something in front of it.
Same thing happened to blue dyes. It used to be very expensive, but Prussian Blue being invented in the 18th Century made it show up everywhere cause it used to be so fancy, and then it just became a cheap dye.
Though the French loved that shit for government official and soldier uniforms, and supposedly that's why cops wear blue
there's indigo and another plant that grows in europe and also makes indigo but less, so you can just farm this thing, unlike purple dye that requires tons of work, and depending on period it was used by commoners (before 1200 or so, in western europe)
it's a bit funny to look at this today, but woad (that euro indigo) trade was a big deal, it got protected by tariffs and blockades and diplomacy, and all for nothing, ultimately both woad and indigo farming was completely destroyed by synthetic indigo production. indigo wasn't first/easiest dye to make, but it's far from the most complex thing you can cook, even in 1900s. prussian blue is much cheaper than synthetic indigo anyway
Blue LEDs used to be 450nm with narrow fov. Now we're getting them in low 200nm in the UVA, UVB and the very dangerous eye sight blinding UVC.
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