| 摘要 |
PURPOSE:To measure a rotational angle precisely by a method wherein an object light and a reference light are emitted from one side in an apparatus making relative displacement, a hologram serving as a reference and a hologram made after displacement are formed thereby through the intermediary of two parallel reflector boards provided on the other side in the apparatus and interference fringes formed between the holograms are counted. CONSTITUTION:A laser beam from a light source 9 is divided in two by a half mirror 17 and a light F1 thus made turns to be an object light through a mirror 13, a lens 14, a diffusion board 15 and a lens 16, while a light F2 turns to be a reference light of parallel luminous flux exposes a photosensitive material located in the position of a hologram 6 through a reflecting element 3 composed of two parallel reflector boards to form a hologram serving as a reference. Next, in a state that the reflecting element is rotated, the laser beam is divided in two in the same way as in the preceding process and a regenerated object light is obtained from the hologram 6 by the light F2. And when the object light obtained by the light F1 is applied on the hologram 6 through the intermediary of the reflecting element 3 in a new position, it interferes with the regenerated object light, whereby the interference fringes are formed on a screen 8. By this constitution, the rotational angle can be determined with excellent precision from the width of the fringes correlating to the rotational angle. |
