| 摘要 |
A method and apparatus for measuring vertical surface variations of a specimen is disclosed wherein the specimen is mounted in movable relation to an objective lens assembly, a reticule being arranged at a focal plane of the objective lens assembly, movement between the objective assembly and the specimen necessary for maintaining the reticule in focus upon different surface portions of the specimen providing an indication of vertical spacing between the surface portions. Another embodiment of the invention contemplates a three-dimensional reticule arranged at or adjacent a focal plane of an objective lens assembly for simultaneously focusing portions of the reticule upon different surface portions of the specimen, the reticule being adapted to provide an indication that the vertical spacing between the different surface portions of the specimen is within acceptable limits.
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