Biological property check device using light

A detection apparatus for optically determining a biological material property, comprising:

• a probe base;
• a plurality of probes two-dimensionally arranged and supported on the probe base, each probe including a light emitting element for applying light to a living body and a light receiving element for receiving light from the living body;
• a material property calculator provided so as to be connectable between a signal input terminal of the light receiving element and a signal output terminal of the light emitting element in each probe, for calculating a material property of the living body;
• a switch circuit for successively switching connection of the material property calculator to the respective probes;
• and
• a display unit for providing a two-dimensional display of the material properties calculated for the respective probes;
• wherein
• the material property calculator comprises:
• an amplifier having an input terminal connected to a signal output terminal of the light receiving element;
• a phase compensation circuit provided between an output terminal of the amplifier and a signal input terminal of the light emitting element for changing the signal frequency so as to cause any phase difference between an input waveform into the light emitting element and an output waveform from the light receiving element to become zero;
• and
• a frequency difference detector which measures a frequency of a self-induced oscillation generated when the phase difference is made to become zero by means of a feedback loop formed by the probe, the amplifier, and the phase compensation circuit, and detects a difference between a frequency obtained when receiving light from the living body by applying light from the probe to the living body and a frequency obtained when such light is not applied to the living body;
• and
• the detection apparatus determines material property of the living body based on a two-dimensional distribution of the frequency differences.