| 摘要 |
PURPOSE:To obtain an apparatus which can detect a state of a face position highly accurately and with high stability even when a shape of a face to be observed is changed locally or a reflectance is changed locally by a method wherein a dislocation between a reference face and the face to be observed is found from a phase difference in a fundamental period of moire fringes formed by two gridlike patterns. CONSTITUTION:The following are provided: projection means 20, 21 which project a gridlike pattern G1 on a reference face 27 and on a face 2 to be observed; a first image-formation means 22 which forms an image of the gridlike pattern G1, reflected from the reference face 27 and the face 2 to be observed, on a face of a gridlike pattern G2 whose pitch is different from a pitch of the gridlike pattern G1; a second image-formation means 23 which forms an image of moire fringes, formed on the face of the gridlike pattern, on a detection face 24a; a detection means 24 which individually detects phases P1, P2 of fundamental periods of the moire fringes which are obtained on the detection face 24a when the gridlike pattern G1 is projected on the reference face 27 and on the face 2 to be observed; a computation means 26 which finds a dislocation between the reference face 27 and the face 2 to be observed from a phase difference between the phase P1 and the phase P2. |
