A New Light

How fast does a light turn on?

I was sat on the train a few weeks ago, and around a bend I could see the light for a level crossing. I noticed that the lights were snapping on and off, obviously LED based. I remember the old slow fade on/fade off of incandescents. The old lights were mellow and soothing, the new ones curt and abrupt.

When I turn on my lights at home there is a lag, a second or two while I have to wait to see if I just turned it on, or the "bulb" has worn out. All the lights in my house are now compact fluorescents.

For the last couple of years I've been noticing how certain cars, predominantly from Lexus, have strobing tail lights. The regular red rear lights are LED based, and driven quite bright. To preserve the LED's, protect them from overheating, they are strobed. Where's the problem? Well, when I scan from looking forward to looking in my rear view mirror the after image of the LED taillight manifests itself as a series of discrete red dots. It's quite distracting.

As wax, oil and tallow gave way to gas, and gas gave way to arc lights and incandescents. Incandescents and strip lights are yielding to LEDS, EL panels and compact fluorescents. I wish I was smart enough to perceive what will be next.