The French website Mizuwari published a series of captivating interviews with the CEO of Sigma, Kazuto Yamaki. Among other things, the Japanese executive mentions the challenges of implementing curved sensor technology in digital cameras.
Simply put, camera lenses are round and project different rays of light on a flat sensor, which is not an ideal solution. This explains, for instance, the softness issue encountered on the corners of the image, especially when shooting wide open. In a perfect world, the shape of the sensor would match the light beam created by the lens. Several manufacturers, such as Sony, have been working for years to develop curved sensors where each pixel could be placed at the perfect distance in relation of the light beam. Easier said than done.