| 摘要 |
PURPOSE:To measure flatness with high accuracy without errors, by detecting the interference fringes associated to a plane to be inspected and a reference plane with image sensors, calculating the flatness and correcting the same in accordance with the detection signal corresponding to the correction region on the reference plane. CONSTITUTION:The interference luminous fluxes generated by a plane to be inspected and a reference plane which are disposed in parallel are made incident to image sensors 34, via a total reflection mirror 32 rotated by a pulse motor 42. The video outputs thereof are taken via a head amplifier 46, a peak holding amplifier 55, one of LPFs 56a-56c, a sample holding amplifier 57, and an AD converter 58 into a microcomputer 48. On the other hand, the output of a rotary encoder 41 operating cooperatively with the motor 42 is read into the microcomputer 48 as well. Flatness is calculated from the positions of the bright fringes in the three positions A-C of a mirror 32 and the pitch of the fringes. The results obtained by the comparison between the values detecting the positions of the thin lines provided on the reference plane and the reference value are subjected to correction for deviation and oscillations of the optical systems, whereby the flatness is measured accurately without errors. |
