Patent ID: 7342652

Claim:
A biomedical optical device comprising: a light irradiating unit which is arranged on a surface of a subject, and configure to irradiate light toward a region to be irradiated in the subject, the light with a wavelength to be absorbed by a target object in the subject and intensity varied in time; at least two detecting elements which are arrayed at different distances from a location of the light irradiating unit, and which detect the light propagated through the subject; a storage unit configure to store the intensity of light detected by each of the detecting elements when the target object is not present in the region to be irradiated; a calculating unit which specifies the detecting element detecting the light which was reflected by the target object or propagated through the target object, by comparing the intensity of light detected by each of the detecting elements when the stored target object is not present in the region to be irradiated with the intensity of light detected by each of the detecting elements when the target object is present in the region to be irradiated, and which calculates the depth of the target object by reference to the location of the light irradiating unit on the basis of the distance between the specified detecting element and the light irradiating unit; and an output unit which outputs the calculated depth of the target object.