What is the terminology for magnetic scale?

Grating scale - a sensor made by using the principle of interference and diffraction of light. When two pieces of grating with the same grating pitch are stacked together, and at the same time let the line form a tiny angle, then under parallel light irradiation, and the perpendicular direction of the engraved line can be seen symmetrically distributed light and dark stripes, known as Moore's stripes, so Moore's stripes is the total effect of light diffraction and interference. When the grating moves a small grating distance, Moore's stripes move a stripe spacing, so that we measure the width of the Moore's stripes is much easier than measuring the width of the grating lines. In addition, since each Moir stripe is made up of the intersection of a number of grating lines, when one of the lines has an error (unequal spacing or tilt), this Magnetic scale - a sensor made using the principle of magnetic poles. The base scale is a uniformly magnetised steel strip, with the S and N poles evenly spaced on the strip, and the changes in the S and N poles are read by the readhead to keep track of the number.

The scale is affected by temperature and is generally used in an environment of less than 40 degrees centigrade. (CMMs are generally required to measure in a constant temperature and humidity environment to ensure the accuracy of the measurement.) Open magnetic scale is easily affected by magnetic field, closed magnetic scale is not so troubled, but the cost is higher.