The difference between the grating ruler and the magnetic grating ruler of the vision measuring machine

Many people can’t distinguish between the grating ruler and the magnetic grating ruler in the vision measuring machine. Today we will talk about the difference between them.
The grating scale is a sensor made by the principle of light interference and diffraction. When two gratings with the same pitch are stacked together, and the lines form a small angle at the same time, then under the illumination of parallel light, symmetrically distributed light and dark stripes can be seen in the vertical direction of the lines. It is called Moiré fringes, so Moiré fringes are the combined effect of diffraction and interference of light. When the grating is moved by a small pitch, the moiré fringes are also moved by one fringe pitch. In this way, we can measure the width of the moiré fringes much easier than the width of the grating lines. In addition, since each moire fringe is composed of the intersections of many grating lines, when one of the lines has an error (unequal spacing or slant), this erroneous line and the other grating line The position of the intersection of the lines will change. However, a moiré fringe is composed of many grating line intersections. Therefore, the change of the position of a line intersection has very little effect on a moiré fringe, so the moire fringe can be used to enlarge and average effect.
The magnetic scale is a sensor made by using the principle of magnetic poles. Its base ruler is a uniformly magnetized steel strip. Its S and N poles are evenly spaced on the steel strip, and the reading head reads the changes of the S and N poles to count.
The grating scale is greatly affected by temperature, and the general use environment is below 40 degrees Celsius.
Open magnetic scales are easily affected by magnetic fields, but closed magnetic scales do not have this problem, but the cost is higher.

Post time: Jul-18-2022