| 摘要 |
A free point tool comprises an elongated main shaft assembly and a low mass sensor assembly coaxially and slidingly disposed over the elongated main shaft. The low mass sensor assembly is adapted to be supported within the down hole casing by first and second drag spring centralizers coupled respectively to upper and lower ends of the low mass sensor assembly. The low mass sensor assembly comprises a magnetic amplifier sensor disposed in a sensor body and having a variable inductance proportionally responsive to longitudinal and rotational displacement of an adjacent sensor plate portion of a movable sensor sleeve concentric with and enclosing the sensor body, wherein the sensor sleeve is attached to the first drag spring centralizer and the sensor body is attached to the second drag spring centralizer.
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