| 摘要 |
PURPOSE:To improve a light transmission characteristic in an optical guide and to enable the miniaturization thereof by disposing a cylindrical lens in front of the optical guide and by providing a reflecting diffraction grating in adhesion on the base part on the lateral side of the optical guide. CONSTITUTION:A cylindrical lens 21 is disposed in front of a bar-shaped optical guide 7 which receives a reflected light or a transmitted light from the surface of a material to be inspected, while a reflecting diffraction grating 22 is provided in adhesion on the base part on the lateral side of the optical guide 7. Since an incident light on the optical guide 7 can be converged by the cylindrical lens 21 according to this constitution, the width of a reflecting surface can be narrowed and also the rate of another incidence of a skew light on the reflecting surface can be reduced. Since besides, the reflecting diffraction grating is used as the reflecting surface, it is possible to reflect and propagate the incident light on the optical guide 7 in the shape of a beam and in the specified direction. |
