| 摘要 |
<p>Light of a specific wavelength is introduced into respective optical fiber members forming a light projecting optical fiber member group (14a) through a condensing lens (26). A second end of an optical fiber light guide path (10) whose first end is brought into close contact with a target (20) is branched into three optical fiber member groups including a light projecting optical fiber member group (14a) and first and second photoreceiving optical fiber member groups (16a, 18a), and each of the optical fiber member groups (14a, 16a, 18a) is formed by bundling optical fiber members forming respective unit bundles respectively. Each unit bundle includes at least one light projecting optical fiber member which is arranged at the center, a first photoreceiving optical fiber member group arranged around the light projecting optical fiber member substantially on the circumference of a first circle concentric with the optical fiber member, and a second photoreceiving optical fiber member group arranged substantially on the circumference of a second circle which is concentric with the at least one optical fiber member and larger in radius than the first circle. <IMAGE></p> |
