| 摘要 |
PURPOSE:To judge internal stress by providing an optical deflecting plate and a 1/4 wavelength plate at the tips of two rotatable cylinders whose axes are the same as the axis of a cylinder in an optical observing system and by observing interference fringes generated in an optical elastic material whose refractive index varies in response to pressure. CONSTITUTION:The observing system is formed by a pipe body 7, a relay lens 8, and eyepiece lens 12, and the like. Optical film 6 is alighed around the peripheral surface of a pipe body 7. An inner tube 21 and an outer tube 22 are rotatably attached to an outer pipe 4 at the outside of the fiber. The polarizing plate 27 and the 1/4 wavelength plate 28 are provided at the tips of the tubes. The polarizing directions of a central part 29 and peripheral part 30 of the polarizing plate 27 are Pa and Pb which cross at a right angle to each other. THe inner and outer tubes 21 and 22 are fixed so that the direction of main axis Q of the 1/4 wavelength plate 28 forms 45 deg. with respect to Pa and Pb. When the light from a light source 17 is irradiated on an object to be measured 36 on which an optical elastic film 38 is applied by a coating material 37, circular polarization is obtained by the periphery 30 of the polarizing plate and the 1/4 wavelength plate 28. The light is reflected by the coating material 37, and pases through the 1/4 wavelength plate 28 and the central part 29 of the polarizing plate. Then the interference fringes are generated. In this constitution, the stress of the object to be measured is determined. This device is suitable for the measurement in inaccessible places. |
