| 摘要 |
PURPOSE:To measure a fine shift in position by superposing a linear photosensor and a slit plate which has a slit slanting slightly to the line direction of the sensor one over the other. CONSTITUTION:The linear photosensor and slit plate which are superposed one over the other are irradiated with light from the side of the slit plate, and then the linear photosensor is irradiated only where it intersects with the slit. When the slit plate is displaced horizontally by DELTAl, the intersection F of the sensor and slit moves greatly to F' and the quantity DELTAL of displacement is DELTAl.cottheta, where theta is the angle that the slit and sensor contain, making it evident that the quantity of displacement is very large when theta is small. For the purpose, the expanded quantity of displacement is detected by the linear photosensor to measure the fine quantity of displacement of the slit plate with high accuracy. |
