| 摘要 |
PURPOSE:To enable a material warpage to be precisely corrected, by measuring the amount of warpage of the material surface on the whole position of the surface and determining the surface height h from the reference plane S so that an amplitude angle of deflection in the electronic beams is determined corresponding to the height h. CONSTITUTION:Coherent laser rays 8 coming from the laser 7 are made to be enlarged parallel rays by a collimator 9. These rays are divided in both directions of the material and the reference plane by a beam splitter 10. Two of the rays reflected on the material plane 1 and the reference plane 11 are combined again on the beam splitter 10, to interfere on an observation plane 12 and form the interferig fringes. In case the reference plane is a flat mirror, an absolute value of a material warpage is determined from contour lines of the interfering fringes. The direction of the warpage is detected by placing a concave mirror K or a convex mirror L on the reference plane 11. Height h (x, y) orientated below from the standard plane S is determined on each point (x, y). Thus, deflection amplitude gamma(x, y) on each point (x, y) is determined in a formula, in correspondence with distance P between the scanning electrode and the standard plane S, and a field size (a).
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