| 摘要 |
PURPOSE:To enable the detection of a spot of a beam with a phtoto detector set behind the emission surface of a fiber when it hits an object to be measured by arranging the incidence surface of the square refracture index based distribution optical fiber at the focal point of a condenser lens and both components on the same optical axis. CONSTITUTION:When a laser beam 4 enters a reflecting body 13 of an object 8 to be measured at an angle (ei) of incidence, the light emitting from the reflecting body enters a squre refractive index-based distribution optical fiber 14 of the incidence surface of the fiber 14 is arranged at the focal point of a condenser lens while both the components are on the same optical axis and a lens 15 is stigmatic. In this case, the displacement (d) and the position of the spot is almost in a linear relationship. Thus, the amplitude and the frequency of vibration of the object 8 being measured can be measured by detecting the movement of the spot with a detector 16 located behind the emission surface of the fiber 14. |
