1. Field of the Invention
The present invention relates to a levelling method and apparatus and, more particularly, to the improvement in a levelling method and apparatus for levelling an object of which the surface shape or surface roughness is to be measured.
2. The Related Art
Levelling apparatuses for controlling an object which is placed on a mounting member so as to have the desired attitude are known and they are generally used to place an object of measurement, a work, etc. on the mounting members of a surface roughness tester, a three-dimensional measuring apparatus and various working machines.
In the case of a surface roughness tester, for example, if the measuring plane is inclined, the base line is inclined in the result of measurement, as shown in FIG. 15 (A), which is unsuitable for obtaining the data on the surface roughness. Furthermore, if a measurable allowance must be set at a wide range in the case as shown in FIG. 15(A), the discrimination of the measurement is impaired. It is therefore necessary to adjust the mounting attitude so as to level in the direction of scanning by the probe (see FIG. 15(B)).
In the case of outputting the surface roughness three-dimensionally by measuring it several times by feeding the probe little by little in the direction orthogonal to the direction of scanning by the probe, the levelling in the direction orthogonal to the direction of scanning constitutes a very important precondition.
In a conventional levelling apparatus, however, the levelling only in one direction is automatized, and no levelling apparatus which is capable of automatic three-dimensional attitude control of an object placed on a mounting member has ever been produced.
As a result, the three-dimensional attitude of an object placed on the mounting member must be adjusted manually, which takes much labor and time.