A device and a method for automatically inspecting objects traveling in an essentially monolayer flow. The device comprises a detection unit through which the object flow passes, consisting of the following: elements for applying electromagnetic radiation in the direction of the plane of conveyance of the objects and defining a lighting plane, the intersection of the lighting plane and plane of conveyance defining a detection line; a receiver device periodically scanning each point on the detection line and receiving radiation reflected by an elementary measuring zone, the plane defined by the detection line and the optical input center being known as the scanning plane; elements for transmitting the reflected radiation. The radiation emitted is concentrated in the region of the lighting plane and the lighting plane and the scanning plane merge, whereupon the joint plane is inclined in relation to the normal of the plane of conveyance.