A lens having an optical axis extending according to a so-called longitudinal axis, intended to be placed on the path of the light rays emitted by a light source so that the optical axis of the lens is parallel to the main axis of emission of the light source, the lens having, in the direction of propagation of the light rays, an input face and an output face, and having a general shape cambered in the direction of the output face, the lens defining a so-called vertical axis, a so-called transverse axis and further having a so-called vertical first midplane, extending in a plane (X, Z) and a so-called horizontal second midplane, extending in a plane (Y, Z), characterized in that: - the input face includes: - an upper portion located above the horizontal midplane, which is configured to divert the light rays, at least according to the vertical axis, so that they are substantially parallel to the horizontal midplane; - and a lower portion located below the horizontal midplane, which is configured to reduce the vertical opening angle (α) of the light beam, according to the vertical axis, between the horizontal midplane and a lower limit (41, 43, 44); - the output face includes: - a central vertical portion substantially planar and orthogonal to the optical axis; - on either side of the central vertical portion, a lateral portion configured to divert each light ray in the direction of the vertical midplane, according to an amplitude of deflection that is even larger as the point of incidence of the light ray on said lateral portion is close to the vertical midplane. - the input face includes: - an upper portion located above the horizontal midplane, which is configured to divert the light rays, at least according to the vertical axis, so that they are substantially parallel to the horizontal midplane; - and a lower portion located below the horizontal midplane, which is configured to reduce the vertical opening angle (α) of the light beam, according to the vertical axis, between the horizontal midplane and a lower limit (41, 43, 44); - an upper portion located above the horizontal midplane, which is configured to divert the light rays, at least according to the vertical axis, so that they are substantially parallel to the horizontal midplane; - and a lower portion located below the horizontal midplane, which is configured to reduce the vertical opening angle (α) of the light beam, according to the vertical axis, between the horizontal midplane and a lower limit (41, 43, 44); - the output face includes: - a central vertical portion substantially planar and orthogonal to the optical axis; - on either side of the central vertical portion, a lateral portion configured to divert each light ray in the direction of the vertical midplane, according to an amplitude of deflection that is even larger as the point of incidence of the light ray on said lateral portion is close to the vertical midplane. - a central vertical portion substantially planar and orthogonal to the optical axis; - on either side of the central vertical portion, a lateral portion configured to divert each light ray in the direction of the vertical midplane, according to an amplitude of deflection that is even larger as the point of incidence of the light ray on said lateral portion is close to the vertical midplane.