Abstract
Circular magnetic scales are used widely as rotary encoders, and conventionally, they are calibrated by measurement of intervals of pulses which are generated from the output of magnetic head. But for the improvement of circular magnetic scales in their accuracy, it has been necessarily required to establish new methods to measure the graduations themselves of scales. As one of the methods, a prototyped automatic calibrating equipment using a high precision index table, a laser interferometer, a micro-computer and a desktop computer, is manufactured. In this method, the index table is used for the standard of angle, and angular errors are transformed into position errors on the tangent of the scale, which are measured by laser interferometer. During experimental measurements of two kinds of scales, it has been confirmed that this calibrating equipment assures us that errors are smaller than +O. 5 second of arc.
