Many people can not distinguish between the grating ruler and the magnetic grating ruler in the visual measuring machine, and today we will talk about where the difference is.
Grating ruler is a sensor made by the principle of interference and diffraction of light. When two gratings with the same grid distance are stacked together, and the lines form a tiny Angle, then under parallel light irradiation, the symmetrical distribution of light and dark stripes can be seen in the vertical direction of the engraving line, we call it the Moire stripe, so the Moire stripe is the total effect of light diffraction and interference. When the grating moves a small grid distance, the Moire fringe also moves one fringe distance. In this way, it is much easier to measure the width of Moire fringe than it is to measure the width of grating line. In addition, since each Moire fringe is composed of the intersection of many raster lines, when one of the lines has an error (unequal spacing or tilt), the intersection position of this error line and the other raster line will change. However, a Moire fringe is composed of many grating line intersection points, so the change in the position of a line intersection point has a very small effect on a Moire fringe, so the Moire fringe can play a role in magnifying and averaging.
Magnetic grid ruler is a sensor made by using the principle of magnetic pole. Its base ruler is a uniformly magnetized steel strip. Its S and N poles are evenly spaced on the steel band, and the change of S and N poles is read by the reading head to count.
The grating ruler is greatly affected by temperature, and the general use environment is below 40 degrees.
Open magnetic grid scale is easy to be affected by magnetic field, closed magnetic grid scale does not have this problem, but the cost is higher.