US Patent 10488618 Optical imaging lens

An optical imaging lens includes a first lens of negative refractive power, a second lens of negative refractive power and of an image-side surface with a concave portion in a vicinity of its optical-axis, at least one of an object-side surface and of an image-side surface of a third lens being an aspherical surface and a fourth lens of an object-side surface with a concave portion in a vicinity of its optical-axis. An aperture stop is disposed between the first lens element and the third lens element. The Abbe number ν1 of the first lens element and the Abbe number ν4 of the fourth lens element satisfy 45≤ν1≤65 or 18≤ν4≤35.