Ultrasonic sensor

An ultrasonic sensor for performing at least one function selected from the group of sensing a spatial area and of measuring contactless a distance, said ultrasonic sensor comprising:

• at least one ultrasonic transducer for performing at least one function selected from the group of sending ultrasonic impulses and receiving the echo of the ultrasonic impulses;
• a device for concentrating the energy of the ultrasonic impulses onto a spatial area to be sensed and for concentrating the energy of the echo of the ultrasonic impulses onto the at least one ultrasonic transducer;
• said device for concentrating the energy having a reflector with a reflective surface;
• said reflective surface comprised of parabolic surfaces of second order;
• said reflector comprising reflector segments that are fixedly or movably connected to one another;
• wherein a first and a second of said reflector segments are outer segments having reflective surfaces that are paraboloid segments of 50.degree. to 120.degree. of a paraboloid of revolution with a first focal point, said paraboloid of revolution generated by a rotation of a first parabola about an axis of symmetry thereof by an angle of rotation .alpha.;
• wherein a straight line, intercepting said axis of symmetry of said first parabola at said first focal point, contacts said first parabola at a second focal point that is a vertical projection of said first focal point;
• wherein a third of said reflector segments is a first inner segment having a reflective surface embodied as a parabolic surface.