| 摘要 |
In an optical dimension gauging instrument, commonly referred to as a laser micrometer, particularly for use in measuring the outside dimension of elongated cylindrical objects, such as coated wires or steel tubes, in hostile optical environments, including a laser for generating a beam of collimated light, means for directing the light through a measurement zone, photodetector means responsive to the light passing through the measurement zone, and a mirror mounted for rotation by a motor to cause the beam to be scanned repeatedly across the measurement zone, a beam expander is employed to enlarge the output of the laser to a diameter substantially greater than the maximum dimension of normally anticipated foreign objects which might intercept the beam outside the measurement zone, an anamorphic lens further expands the beam in one plane to a size greater than the size of normally anticipated foreign objects both within and without the measurement zone, and a lens system causes the beam to be focused in the other plane in the measurement zone while the expanded beam is projected through the measurement zone with the long dimension of the beam parallel to the cylindrical axis of the article whose outer dimension is being measured.
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