| 摘要 |
PURPOSE:To detect the positions of a 1st and a 2nd bodies with high accuracy by finding the interval between the 1st and 2nd bodies while finding the quantity of the positional deviation in their relative plane. CONSTITUTION:The position of the center of gravity of two 1st and 2nd pieces of diffracted luminous fluxes formed on a specific surface through 1st and 2nd physical optical elements Z1 and Z2 and the position of the center of gravity of two 3rd and 4th pieces of diffracted luminous fluxes formed on the specific plane are detected while separated at a distance larger than the width of the respective pieces of diffracted luminous fluxes. When the quantity W of the positional deviation between the 1st body 1 and 2nd body 2 is O, the optical axis a1 of a physical optical element (e.g. Z1) on the 1st body 1 and the optical axis a2 of a physical optical element (Z2) on the 2nd body 2 are shifted in position by a distance WO to make points C1 and C2, and C3 and C4 separate when the quantity W of the positional deviation between the 1st body 1 and 2nd body 2 is O. Consequently, the positions of the 1st body and 2nd body can be detected. |
