| 摘要 |
PURPOSE:To perform fine displacement detection with high resolution without increasing the number of slits of a moving slit plate greatly by setting the pitch of fixed slits slightly different from the pitch of moving slits. CONSTITUTION:An array of slits of a fixed slit plate 4 operates as a vernier which expands the pitch width of slits of a moving slit plate 3 and makes a read. Transmitted light passed through both slits forms a pattern of a belt of light different in width, bit by bit. This pattern is photodetected by a solid- state image sensor 7 and movement of this pattern is calculated digitally by a detection data arithmetic means 11 through a signal converting circuit 9, thereby calculating the movement distance of the pattern. Consequently, the displacement of the moving slit plate 3 is detected while increased. Namely, this displacement detection has resolution corresponding to divisions of one pitch of the moving slits. |
