| 摘要 |
PURPOSE:To measure a lead shape at high accuracy by permitting a length measurement means employing laser interference to convert displacement following a change in the lead height of a holding means into an electrical signal and to process the rotational angle of a fixed cylinder and the displacement of the holding means so as to detect the lead shape. CONSTITUTION:Since an air slide mechanism is employed as the holding means of a Z table 6 following a change in the height of a lead 101, which results from the rotation of the fixed cylinder 100, air lies on sliding surfaces of the Z table 6. Accordingly an average surface contact can be maintained to reduce the pitching of the Z table 6, and pitching reproducibility is excellent to reduce measuring errors due to the pitching, thereby further improving reproducibility accuracy. A laser interferometer 22 using He-Ne laser as a Z-axis scale counts interference moire repeating dark and bright at every 1/4 wavelength, and electrically divides it to 1/10, whereby measuring errors due to reading the Z-axis scale can be reduced. And measurement at the high accuracy in terms of submicron can be attained. Thus the lead shape of a video head can be measured at high accuracy.
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