| 摘要 |
In the present invention, multiple detected portions (32-1 to 32-m) are formed, for example, in substantially the same position in a longitudinal direction of a light guide member (16) and in different orientations in a circumferential direction thereof. Each detected portion includes an optical property-changing member that generates an optical signal having an absorption wavelength feature region, which is different for each detected portion, by changing the optical properties of a sensor light that is guided by the light guide member from a light source (12) according to the amount of curvature of the light guide member. The optical property-changing member comprises metal particles that absorb light of a predetermined wavelength region and has a special spectral absorption spectrum that is different from the spectral absorption spectrum natural to the metal. The multiple detected portions have optical property-changing members with different special spectral absorption spectra from one another disposed therein and the special spectral absorption spectra of all the optical property-changing members overlap at least partially with an emission wavelength region of the sensor light. |
