A new digital subdividing technique for grating signal and its error analysis

In a high precision measurement instrument using the radial grating as the graduated reference, a linear signal is generated from the sinθ and cosθ signals that are the output of the grating reader. By detecting the zero points of the generated signal and the original signals, the eight-fold subdivision for Moiré fringes is carried out. Then the amplitude of the linear signal is segmented using digital computing method, and the ten-fold subdivision for Moiré fringes is implemented using the LUT technique. Furthermore, the error induced by the technique is analyzed in the paper. Compared with the common subdividing techniques, it has many advantages such as simple electronic circuit, little subdividing error, and convenient for error correction. Thus high precision angle measurement is realized.