Exterior rearview mirrors are typically convex mirrors rather than flat ones. Convex mirrors are used because, although the images they produce appear smaller than the actual objects, they provide a wider field of view, helping the driver better monitor the situation behind the vehicle.
Automotive exterior rearview mirrors are usually convex, primarily to expand the field of view and minimize blind spots. While the images produced are smaller, the mirror captures a broader area, thereby enhancing driving safety.
Wider field of view: Convex mirrors diverge light rays; compared to flat mirrors, they reflect a larger area of road conditions, helping drivers clearly see vehicles approaching from the side and rear.
Reduced blind spots: Because the mirror surface is a convex (outward-curving) sphere, it covers more "dead zones," making it easier to spot adjacent vehicles when changing lanes or turning.