Projector, projection system, and detection light radiator

A projector comprising:

• an exterior enclosure that forms an exterior of the projector;
• a light source apparatus;
• a light modulator that modulates light outputted from the light source apparatus to form a projection image;
• projection optical apparatus that projects the projection image formed by the light modulator;
• a plurality of detection light radiators that radiate detection light used to detect a pointing element onto a projection area where the projection optical apparatus projects the projection image;
• an imager that receives light that belongs to a wavelength region including a wavelength of the detection light to capture an image of the projection area;
• and
• a position detector that detects a position of the pointing element in the projection area based on the image captured by the imager,
• wherein the plurality of detection light radiators are arranged in different positions on the exterior enclosure,
• the plurality of detection light radiators include a first detection light radiator, and
• the first detection light radiator is so configured that a distance therefrom to another detection light radiator out of the plurality of detection light radiators is changeable.