Scanner

A scanner comprising:

• a light projecting unit that projects detection light;
• a scanning unit that scans the detection light projected from the light projecting unit in a circumferential direction around a rotation axis;
• a light receiving unit that receives reflected light obtained by the detection light scanned by the scanning unit and reflected by an object in a detection area, and generates a light receiving signal;
• a calculation unit that calculates a distance to the object based on the light receiving signal generated by the light receiving unit;
• a storage unit that stores information of a monitoring area set in advance in the detection area;
• a determination output unit that determines entry of the object into the monitoring area based on the distance calculated by the calculation unit and a scanning angle of the detection light scanned by the scanning unit, and outputs a control signal;
• a casing that houses the light projecting unit, the scanning unit, the light receiving unit, the calculation unit, the storage unit, and the determination output unit;
• and
• a light transmissive cover provided on the casing and configured to transmit the detection light projected from the light projecting unit, wherein
• the light projecting unit projects a first detection light and a second detection light that constitute a detection light group regarded as being emitted in a predetermined single direction, the first and second detection lights being emitted at different timings and different scanning angles accompanying rotation of the scanning unit from positions spatially separated on the light transmissive cover.