I just returned from a nice cruise, visiting hot and sunny countries like the South of Italy, Greece, and Israel. I was very surprised to see how many headlamps had external lensed entirely obstructing the passage of light and also less frequently, the interior of the headlamp fogged or blackened. A measurement would have shown no really problematic level of glare because transmission is so low, but lamps in this condition give no real seeing distance. I am quite sure some headlamps I saw had a transmission factor under 20%. Although the North American technical regulations and tests for plastic lenses are different than the UN (ECE) ones, the problem is the same there—North American lens durability standards are different, but equally inadequate.
I am proud—as all of us should be—of the progress in automotive lighting these last 15 years with HID, then AFS and intelligent lighting, and now with the LED technologies. Lighting suppliers have done a great job but seem to have forgotten the basis of their target, a reasonably constant (or at least reasonably acceptable) level of lighting safety performance from the first km until the car reaches the end of its service life. Today’s cars are capable overall of providing an unprecedented long service life, and it is our responsibility to make sure the headlamps are able to survive for the long haul. You will find in this week’s news an interesting description of one maker’s advances in aircraft lighting. The concept of Photometrical Operating Life is mentioned—basically, the durability of a lighting device’s compliance with the photometric requirements. Now that we have life-of-car light sources, we are past due to apply such a concept to the design and construction of road going lamps.
I suggest first to do a survey in order to quantify the catastrophically bad results we will find in some countries where also the number of pedestrian fatalities is so high.
Next, we should launch studies and experiments to devise lens material durability standards and tests more realistic and stringent than today’s obviously inadequate ones. In a third phase, we would work to speed the introduction of these standards and tests in the regulations. I am not in favor of excessive regulation, but this is a big, systematic problem caused by a specific weakness in the regulations, and we must do the responsible thing and fix it. If we do not, all the developments in new light sources and optical techniques will continue to be cancelled out by something as simple and basic as degradation of the plastic lens materials. We must address this properly and promptly.
DVN General Editor