Abstract: An imaging lens includes first, second, third, and fourth lens elements arranged from an object side to an image side in the given order. The first lens element has a positive refractive power, and a convex object-side surface. The second lens element has a negative refractive power, and an image-side surface with a convex portion. The third lens element has an object-side surface with a concave portion. The fourth lens element has an object-side surface with a convex portion, and an image-side surface with a convex portion and a concave portion.

Abstract: A collimating lens includes a first end face with an LED accommodation hole for accommodating an LED lamp, a second end face, which is disposed opposite to the first end face and has an area greater than the first end face, and a sidewall, which is connected between the first end face and the second end face and has a first wall section and a second wall section. The second wall section extends from the second end face toward the first end face to a predetermined distance. The first wall section having one end connected to the second wall section and the other end extending toward the first end face to a predetermined distance. The first wall section defines with the second wall section a contained angle smaller than 180°.