If you've ever been lucky enough to travel to (or live in) Japan, you might have noticed that some stoplights are not red, yellow, and green, but instead red, yellow, and greenish-blue (almost decidedly turquoise).
Although the color of stoplights is codified by international law (read the Vienna Convention on Road Signs and Signals if you're curious), Japan's
bluish-green stoplights have a linguistic origin: historically, the Japanese word au covered the spectrum of both blue and green. Although a word meaning only green (midori) was added to the language centuries ago, the linguistic blending of the two colors persists in the language today.
For example, au-ringo literally means "blue apple." Similarly, the Japanese driver's exam reportedly requires the driver to be able to distinguish between red, yellow, and blue.
Rather than overcome the hurdle of an embedded linguistic (and thus cultural) practice, for something that doesn't matter that much anyway, in the 1970s the Japanese government mandated that stoplights would be a very blue shade of green. Bleen. So it still makes perfect sense to describe them as au.
There are, of course, many established and inviolable transportation standards, especially where safety is concerned. But others, perplexingly, don't exist at all. Today, optical engineers are working with automotive manufacturers to develop heads-up displays for windshields, but there are no standards to guide or assess the safety of these displays. Is it a good idea to display extra layers of "helpful" information in the driver's field of view?
Lidar, which has moved beyond R&D into fierce commercial competition, also lacks published standards to dictate what is required from an automotive lidar system. Today, numerous different technology approaches are market ready, and they deliver different results, with different levels of safety and performance.
And, as we move toward Industry 4.0—a not-so-distant era when our cars will "talk" to traffic signals, buildings, other cars, and yes, possibly even pedestrians—what will emerge as the standard of blisteringly fast 6G communication?
Although the automotive industry is, in many ways, well established, the future remains unsettled. New optical technologies continue to disrupt the status quo, from displays to communication to navigation. While a car built in 1940 is very mechanically similar to a low-end car built in 2005, the past 15 years have seen a glut of new technologies to improve safety and comfort. And, if the stories in this issue of Photonics Focus are any indication, we can expect that the vehicles of the next 15 years will completely transform what it means to commute.
Gwen Weerts, Managing Editor, Photonics Focus
