A sensor comprises a detector defining a zone axis and adapted to receive a signal from within a zone around the zone axis and to generate an electrical signal, and a display module defining a display plane and adapted to display a pattern in the display plane based on the electrical signal, the display being oriented along an axis forming an angle with the zone axis such that the pattern is visible both from a direction parallel to the zone axis and from a direction perpendicular to the zone axis. In certain examples, the angle is about 45°, 40°-50°, 35°-55° or 25°-65°.