Patent ID: 7324211

Claim:
An optical tomographic image obtaining apparatus that divides a low coherent light beam, having a coherence length of 20 μm or less, into a measuring light beam and a reference light beam; changes the optical path length of at least one of the reference light beam and the measuring light beam; irradiates the measuring light beam onto a target of measurement; receives the measuring light beam, which is reflected from the target of measurement; causes the reflected measuring light beam and the reference light beam to interfere; and measures the light intensity of the coherent light after the interference, to obtain optical tomographic images of the target of measurement, comprising: irradiation direction rotating means, for causing the irradiation direction of the measuring light beam to rotate about a single point; optical path length changing means, for changing the optical path length of at least one of the reference light beam and the measuring light beam, synchronous with the rotation of the irradiation direction of the measuring light beam; an objective lens system, for focusing the measuring light beam; and focusing position moving means, for moving the focusing position in the direction of the optical axis of the measuring light beam, by moving the focal point of the objective lens system, synchronous with the rotation of the irradiation direction of the measuring light beam.