摘要 |
A light source section outputs optical flux having two types of wavelength, which are a short wavelength and a long wavelength, while the intensity is made variable. The optical flux is made incident to a detected surface of a body to be detected at a predetermined incident angle simultaneously or alternatively. Based on a type of optical flux outputted from the light source section and an output from a first light intensity detecting section, at least the intensity of the optical flux having a long wavelength outputted from the light source section is adjusted. The output from the first light intensity detecting section in irradiating the optical flux having a short wavelength is compared with the output from the first light intensity detecting section in irradiating the optical flux having a long wavelength. A signal that appears only in the output from the first light intensity detecting section in irradiating the optical flux having a long wavelength is identified as a detected signal from an internal subject. The intensity of optical flux having a long wavelength is adjusted. A disappearance level near a point where the detected signal from the internal subject disappears is calculated. The first intensity of optical flux having a long wavelength is set to level higher than the disappearance level. Based on the output from the first light intensity detecting section obtained by the optical flux having a long wavelength of the first intensity, a subject inside the body to be detected is measured.
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