A quartz glass body with vacuum-evaporated ruled grating scale serves as a reference scale. The absolute dividing accuracy for a measuring range from, for example, 0 to 50mm is min. 0.00025mm.
This directly corresponds to the internal measuring accuracy of a measuring head. The heat-extension factor of this quartz-glass reference body is by more than factor 20 smaller than that of metal.
This means that inevitable temperature changes have proportionally less influence on the measuring result than in the case of measuring systems, which operate with metallic reference elements (analogue measuring devices).
The individual measured values are obtained by opto-electronic scanning of the ruled grating at a scanning frequency of up to 25 kHz. The final measured value is found by differentiating of the individual measured values of the corresponding measuring heads.
It is also possible to measure against a reference roller, whose concentricity must be higher than the required measuring accuracy.
After each measuring process, the system can be recalibrated by directly placing the measuring probes on top of each other and zeroing them.This ensures a high level of measurement reliability and accuracy.Long-term wear and thermal deformations are constantly compensated for, since every measuring process starts from the current zero position.