An Investigation of the Planar 3-DOF Nanoscale Positioning Measurement Method Based on Cross-Encoded Pattern

Precision positioning measurement technology based on microvision has important applications in high-end manufacturing fields such as semiconductors and machine tools. Currently, measurement methods based on pseudo-periodic patterns can break the limitations of periodic patterns and achieve a larger measurement range. However, existing methods have not considered the impact of defocus caused by large-range displacement or assembly misalignment on measurement accuracy. Additionally, the physical period of pseudo-periodic encoding units and the bit number are interdependent, which requires careful tradeoffs when expanding the measurement range. To address these issues, this article innovatively proposes a plane 3-DOF nanoscale positioning measurement method based on adaptive cross-encoded pattern (ACEP). By utilizing high-precision etching technology to ensure the center information of the patterns and encoding the size information of the pattern units, the proposed method mitigates the impact of defocus on measurement. A key advantage of the cross-encoded pattern design is its range scalability, which allows the pattern size to be adjusted to extend the measurement range. Experimental results show that the proposed method achieves a linear resolution of 20 nm and an angular resolution of 20 s, and the measurement accuracy remains stable over a 9-mm displacement range, demonstrating the method’s effectiveness and stability at nanoscale precision.