Imaging lens and solid state imaging device

摘要

According to one embodiment, an imaging lens includes a first optical system and a microlens array. The first optical system includes an optical axis. The microlens array is provided between the first optical system and an imaging element. The microlens array includes microlens units provided in a first plane. The imaging element includes pixel groups. Each of the pixel groups includes pixels. The microlens units respectively overlap the pixel groups when projected onto the first plane. The first optical system includes an aperture stop, a first lens, a second lens, a third lens, and a fourth lens. The first lens is provided between the aperture stop and the microlens array. The second lens is provided between the first lens and the microlens array. The third lens is provided between the second lens and the microlens array. The fourth lens is provided between the third lens and the microlens array.

主权项

1. An imaging lens, comprising:
a first optical system including an optical axis; and a microlens array provided between the first optical system and an imaging element, the microlens array including a plurality of microlens units provided in a first plane, the imaging element including a plurality of pixel groups, each of the pixel groups including a plurality of pixels, the microlens units respectively overlapping the pixel groups when projected onto the first plane, the first optical system including:
an aperture stop;a first lens provided between the aperture stop and the microlens array, the first lens having a first surface, a second surface, and a positive refractive power, the first surface opposing the aperture stop, the second surface being provided between the first surface and the microlens array;a second lens provided between the first lens and the microlens array, the second lens having a third surface, a fourth surface, and a negative refractive power, the third surface opposing the second surface, the fourth surface being provided between the third surface and the microlens array;a third lens provided between the second lens and the microlens array, the third lens having a fifth surface, a sixth surface, and a positive refractive power, the fifth surface opposing the fourth surface, the sixth surface being provided between the fifth surface and the microlens array; anda fourth lens provided between the third lens and the microlens array, the fourth lens having a seventh surface, an eighth surface, and a negative refractive power, the seventh surface opposing the sixth surface, the eighth surface being provided between the seventh surface and the microlens array, a curvature radius of the first surface being positive, each of a curvature radius of the third surface and a curvature radius of the fourth surface being positive, each of a curvature radius of the fifth surface and a curvature radius of the sixth surface being negative, each of a curvature radius of the seventh surface and a curvature radius of the eighth surface being positive, at least one selected from the first to eighth surfaces having an aspherical configuration, Formulas (1) to (5) being satisfied, where
f is a focal length of the first optical system,f1 is a focal length of the first lens,f2 is a focal length of the second lens,f3 is a focal length of the third lens,TL is a distance between the aperture stop and the imaging element,R7 is a curvature radius of the seventh surface,R8 is a curvature radius of the eighth surface, andD34 is an air spacing distance along the optical axis between the third lens and the fourth lens:
0.85≦f1/f<1.0  (1)1.5<|f2|/f<3.0  (2)TL/f<1.3  (3)1<(R7+R8)/(R7−R8)<5  (4)0