Don't buy cheap lightbulbs for your car

Yesterday I had to go to the vehicle inspection with my car. Sadly enough, the headlights didn't pass the test. If you look at the picture of the lightbeam projected on my garage door, you can see why. The light to the right is diffracting a lot of the light upwards, which would blind oncoming cars.

When you look at this closeup, you can see the diffraction pattern even clearer. Several trips between automobile inspection and the car dealership didn't bring us a solution. The conclusion was that the whole headlight unit was faulty and needed (expensive) replacement.

When I got home, I swapped the left and right lightbulbs. Apparently, the problem now also switched sides. When I inspected the faulty lightbulb more closely, it appeared to have a molten reflector. When you look at the dark area in the top, you can see clearly that on the far side of the picture it seems like the reflector material has dripped down a bit. Because of the irregular diffraction pattern this caused, the mechanics couldn't adjust the light beam correctly.

This happened with a dirtcheap nobrand lightbulb. I guess I'll be sticking with Philips lightbulbs from now on. The funny thing is that neither the mechanic nor the people at the technical inspection where able to point in the direction of the solution. If I wouldn't have found this out by accident, I would have been in for an expensive headlight unit replacement.