An optical sensor (10, 110, 210, 310, 410) for the detection of objects in a monitored zone in accordance with the principle of triangulation, the optical sensor (10, 110, 210, 310, 410) comprising a light transmitter for transmitting transmitted light into the monitored zone, wherein the light transmitter comprises at least two light sources (34A - 34C) laterally spaced from each other, and a transmission optics; a light receiver that has a plurality of reception elements for receiving transmitted light from the monitored zone that is remitted by an object to be detected; and a reception optics arranged upstream of the light receiver for generating a light spot on the light receiver from the remitted light, wherein the light transmitter, the light receiver, and the reception optics are arranged with respect to one another such that the position of the light spot on the light receiver in a direction of triangulation results in dependence on a distance of a location in the monitored zone wherefrom the transmitted light is remitted, wherein the transmission optics is configured to form the light emitted by the at least two light sources (34A - 34C) to form a transmitted light bundle of rays, wherein the light bundle has a first focal point for rays propagating within a first plane and a second focal point for rays propagating within a second plane which is perpendicular to the first plane, wherein the distance of the first focal point from the transmission optics is shorter than the distance of the second focal point from the transmission optics, wherein the transmission optics comprises an astigmatic lens arrangement having a first focal length for rays propagating in the first plane and a second focal length for rays propagating in the second plane, wherein the first focal length is smaller than the second focal length, and characterised in that the astigmatic lens arrangement is constituted by one astigmatic lens (38, 138, 238) having a first surface facing to the light source (34A - 34C) being convex within the first plane and concave within the second plane and a second surface facing to the monitored zone being convex. a light receiver that has a plurality of reception elements for receiving transmitted light from the monitored zone that is remitted by an object to be detected; and a reception optics arranged upstream of the light receiver for generating a light spot on the light receiver from the remitted light, wherein the light transmitter, the light receiver, and the reception optics are arranged with respect to one another such that the position of the light spot on the light receiver in a direction of triangulation results in dependence on a distance of a location in the monitored zone wherefrom the transmitted light is remitted, wherein the transmission optics is configured to form the light emitted by the at least two light sources (34A - 34C) to form a transmitted light bundle of rays, wherein the light bundle has a first focal point for rays propagating within a first plane and a second focal point for rays propagating within a second plane which is perpendicular to the first plane, wherein the distance of the first focal point from the transmission optics is shorter than the distance of the second focal point from the transmission optics, wherein the transmission optics comprises an astigmatic lens arrangement having a first focal length for rays propagating in the first plane and a second focal length for rays propagating in the second plane, wherein the first focal length is smaller than the second focal length, and characterised in that the astigmatic lens arrangement is constituted by one astigmatic lens (38, 138, 238) having a first surface facing to the light source (34A - 34C) being convex within the first plane and concave within the second plane and a second surface facing to the monitored zone being convex.