The idea of preserving night vision is based on rod cells being insensitive to light with a wavelength >640nm (ie red).
Halogen bulbs found in headlights produce a lot of light under that wavelength, and are going to be at a much higher intensity than turquoise indicator lights.
> Halogen bulbs found in headlights produce a lot of light under that wavelength, and are going to be at a much higher intensity than turquoise indicator lights.
Tangential, but holy shit, this is great to know, and explains why I generally feel blinded every time someone with those horrible headlights drives by.
I wonder if there’s anything that can be done (to my windshield? to some glasses?) that can reduce the impact of this at night?
You're going to be disappointed. You'd need to blind yourself. That red wavelength is at the bottom of the visible spectrum. Any light that looks not-read is above this threshold. That includes old kerosene and acetylene lamps from before cars were common as well as all other "white", "yellow", or "amber" lamps.
Also, halogen is an old lamp type that has been in use since the 1960s. Then towards the 1990s, there were changes in optics with "projector" housings for halogens, and then the shift to high-intensity discharge (HID aka xenon) lamps. The latest ones now are LED, of course.
In Germany they’ve been developing headlight arrays that can very specifically track the road. But it wouldn’t fly in the U.S. because people aren’t required to keep their cars to the same level of maintenance as over there.
Halogen bulbs found in headlights produce a lot of light under that wavelength, and are going to be at a much higher intensity than turquoise indicator lights.