OPTICAL DIAGNOSTIC DEVICE

PURPOSE:To obtain an optical diagnostic device capable of safely conducting an operation by detecting a boundary between a normal tissue and a lesion tissue in a vital tissue. CONSTITUTION:In a suction probe 13 which is inserted into a head part 22 for excising a lesion tissue 14, such as a tumor, by a rotating blade and sucking it out, a leading end of an optical fiber 11a introducing a low-interference light is inserted. Low-interference lights generated in SLDs 6a, 6b of a light generation part 5 are emitted from the leading end face of the optical fiber 11a. Reflected lights from the lesion tissue 14 are introduced to an interference light detection part 31, where the reflected lights are made to interface with a reference light varying in light path length. In this manner, the reflected lights are detected in a depth direction. The existing range of the lesion tissue 14 is judged from the signal of the ratio of the reflected lights having two wavelengths.