Oscaron

One of the more ridiculous modern myths is that there is nothing wrong the brightness of today's headlights and that it's just a matter of how they're aimed.

While the aiming of bulbs is important, there are definitely some bulbs on the market that are way too damned bright.

I'm driving in full daylight, with glasses that tint automatically, and the blue white standard headlights of a car behind me were bright enough to hurt my eyes.

And it was a low slung compact.

Apr 13, 2023 at 7:28pmMastodon for Android
Show threadGraham Sutherland / PolynomialApr 13, 2023
@Oscaron Spectral distribution is also a big factor. LED headlamps suffer from the "green gap" issue (phosphide LEDs are good at red and near-IR, nitride LEDs are good at blue and violet, nothing is efficient in the 525-575nm green-yellow-orange band) so they can't efficiently produce a lot of light in the 2000-3000K CT range. It's one of the reasons we've seen a shift to manufacturers installing horrible 4000-6500K cold-white headlamps.
Show threadGraham Sutherland / PolynomialApr 13, 2023
@Oscaron BMW has a partial solution for this involving the use of a backfacing laser diode fluorescing a phosphor-coated plate within the headlight cluster, but they're expensive and monolithic. The laser diode itself has a lifetime of over a decade, but if you crack or damage the light cluster (an instant MOT failure) there's no way to separate the headlight optical assembly out and you have to replace the whole unit.
Show threadGraham Sutherland / PolynomialApr 13, 2023
@Oscaron On this note, it would be extremely interesting to see someone develop a headlight that produces coherent light (e.g. via direct laser illumination) with controlled polarisation to ensure that the incident light is more heavily filtered by polarisation filters on windscreens.