| 摘要 |
A pair of pneumatic cylinders is used to counterbalance the weight of a large gantry supporting the optical head of an interferometric profiler. The gantry is supported by the cylinders within pairs of linear-bearing rail that provide a large vertical travel. The pressure in the cylinders is adjusted so as to provide an upward force sufficient to oppose the weight of the gantry and prevent its descent, but not so great as to cause it to rise. In essence, the counterbalance pressure is adjusted to equilibrate the weight of the gantry in such a way that a small force applied manually upward or downward will cause the gantry to move easily in either direction, thereby making it possible for an operator to position the optical head rapidly and with minimum effort as required for the initial alignment with a test object.
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