Detection device

A detection device comprising:

• a light source configured to emit light;
• a planar optical sensor in which a plurality of optical sensors configured to detect the light from the light source are two-dimensionally arranged;
• an object placement part provided so as to allow an object to be detected to be placed such that the object to be detected is interposed between the light source and the planar optical sensor;
• and
• a processor configured to perform operation control of the light source and the planar optical sensor and processing based on outputs of the optical sensors, wherein
• the object to be detected is a culture medium accommodated in a dish of a container,
• the planar optical sensor is configured to output data reflecting an intensity of the light that has been emitted from the light source and reached the optical sensors through the object to be detected, and
• the processor is configured to determine a boundary between a proliferation area and a non-proliferation area of culture targets based on a level of a degree of light transmission of the culture medium that varies according to a degree of proliferation of the culture targets that are cultured on the culture medium, and
• the boundary is in a position that is closest to a position where a rate of change in the degree of light transmission of the culture medium is relatively highest among positions where the rate of change in the degree of light transmission of the culture medium is equal to or less than a predetermined value within an area where the degree of light transmission of the culture medium changes from a relatively higher side toward a relatively lower side.