Harmonic Suppression Method for Optical Encoder Based on Photosensitive Unit Parameter Optimization

Optical encoders are high-precision positioning sensors based on the principle of grating diffraction. However, harmonic distortion remains a critical factor limiting the further improvement of measurement accuracy. In response to this challenge, this paper proposes a strategy to suppress harmonic components in the output signals of optical encoders. In this work, a general expression for the light intensity distribution of the grating image is derived. Then, orthogonal sine-cosine signals are generated using a grid photoelectric sensor array, which replaces the conventional slit grating. Furthermore, a method for the co-optimization of the photosensitive unit width and offset is proposed, which effectively suppresses the third and fifth harmonic components. Theoretical and simulation results collectively demonstrate that the proposed method achieves near-complete suppression of the third and fifth harmonics, leading to a significant improvement in output signal quality. This work provides an effective approach for developing high-precision optical encoder systems with low harmonic distortion.