METHOD AND APPARATUS FOR CALIBRATING A LENGTH OF A PRODUCT

摘要

A contactless calibration of an object length, especially end gauges (1) length, utilizes white light, which is brought to a detector (11) so that a part of the light reflects from a first face of the end gauge (1), another part passes by the end gauge (1) and still another part, which is used as a reference, reflects from a second face of the end gauge (1). Another part of the white light from the same light source (2) as a reference is brought to the' detector (11) after reflecting from a sliding reflective surface (10). By moving the sliding reflective surface (10) the : reference light beam path length is changed, whereas states, wherein the reference light beam path length equals to path length of the light beams reflected from the first and the second faces of the end gauge (1) and the light beam passing' by the end gauge (1), are detected. At the positions of sliding reflective surface (1), wherein the path lengths congruity occurs, an amplification of a light signal, appears on the detector (11) because only when the path lengths are coincident the light beams fall on the detector (11) in the same phase. By comparing the sliding reflective surface (10) distances at the states of amplified light beam on the detector (11) the end gauge (1) length is determined.