IMAGE SENSORS WITH MULTIPART DIFFRACTIVE LENSES

An image sensor may include an array of imaging pixels. Each imaging pixel may have a photosensitive area that is covered by a respective multipart diffractive lens to focus light onto the photosensitive area. The multipart diffractive lenses may have multiple portions with different indices of refraction. The portions of the diffractive lenses closer to the center of the diffractive lenses may have higher indices of refraction to focus light. Alternatively, the portions of the diffractive lenses closer to the center of the diffractive lenses may have lower indices of refraction to defocus light. The multipart diffractive lenses may have stacked layers with the same refractive indices but different widths.