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Driver's med: Rearview mirror, sans the blind spot

A mathematician with a passion for optics has devised a rearview mirror that he says eliminates that bane of lane-changing, the blind spot. Andrew Hicks, an associate math professor at Drexel University in Philadelphia, designed a convex driver's side mirror that gives a wide field of view without significantly distorting the reflected image. But don't look for his innovation on U.S. cars anytime soon—left-side mirrors in the States are required to be flat.

Challenged by a colleague to improve on the distorting bubble-shaped mirrors made for bicycle handlebars, as noted by the Philadelphia Inquirer, Hicks instead developed an automotive prototype. During highway road tests, Hicks tells SciAm.com that cars passing on the left remained in his mirror-augmented field of vision. "If you watched them come up behind you in the mirror, then when they disappeared from view in the mirror was almost exactly when they reappeared in your regular view," he says.

According to a patent filed by Drexel on Hicks's behalf, lane changes and mergers accounted for 4 percent of vehicular accidents in 1994—a number "largely attributed to the minimal view provided by side view mirrors."

Hicks says the shape of his mirror is the product of computer-assisted approximations to complicated mathematical equations. In this case, he wanted a mirror that could cover the usual blind spot without distorting the shapes reflected. As it turned out, that could be accomplished with a subtle, varied curvature.

"It's designed to just capture 45 degrees and no more, and it doesn’t have to be terribly curved to do that," Hicks says. "If you look at a spherical mirror that a truck or bus often has, or an attachment that you might buy as an aftermarket product for your car, those spherical mirrors give a huge amount of view, and there's a lot of distortion. And you really don't need all that extra stuff; you're seeing things that you don't really care about."

Current federal safety standards for motor vehicles require driver's side mirrors to be of "unit magnification"—that is, a planar surface that doesn't magnify or shrink what it reflects. (Hicks says that his design might still find use as an aftermarket product in the U.S., perhaps as an adhesive complement to regular mirrors.) Convex mirrors, stamped with the familiar warning "Objects in mirror are closer than they appear," are permitted on the passenger side, but Hicks has yet to find the ideal solution for that application.

"There are some things I haven't been able to find the answer to, like the passenger-side mirror," he says. "I don't know if there's a good answer that's out there that I'm missing or if it just doesn't exist."

Photo of Hicks's prototype (top) and standard driver's side mirror (below) courtesy of Andrew Hicks

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