VILNIUS TECH Library invites you to follow the published new dissertations. The dissertation „Development and investigation of methods to improve characteristics in optical linear encoders„ prepared by VILNIUS TECH, Xinji Lu. The dissertation was prepared in 2021–2025. Scientific Consultant – Prof. Dr Audrius Banaitis.
The dissertation was defended at the public meeting of the Dissertation Defense Council of Mechanical Engineering in the Aula Doctoralis Meeting Hall of Vilnius Gediminas Technical University at 2 p. m. on 10 June 2025.
Optical linear encoders are crucial for high-precision measurement systems used in industries like CNC machining, semiconductor manufacturing, 3D printing, and robotics. They offer better accuracy and resolution than other technologies, but practical challenges, such as subdivisional error (SDE) and installation errors, limit their performance. These issues affect surface quality and motion precision, especially in applications requiring high precision. Despite the research, existing solutions often fail to address these challenges under real-world conditions, highlighting the need for methods that enhance encoder accuracy and reliability by reducing SDE and improving mounting tolerance. This research explores new approaches through theoretical modelling and experimental validation. Advanced mask-less lithography technology is used to create custom main gratings with harmonic suppression patterns to reduce odd-order harmonic distortions, a primary cause of SDE. A hybrid-grating design for open-type optical linear encoders is introduced to improve mounting tolerance and stabilize light distribution over a wider installation gap. MATLAB simulations model the light distribution properties, and experimental testing is conducted on a platform replicating industrial conditions to ensure practical relevance. A key innovation of the dissertation is the hybrid-grating design, which improves mounting tolerance and signal integrity under sub-optimal installation conditions. This design reduces sensitivity to environmental and mechanical disturbances while addressing odd-order harmonic distortions, thus reducing SDE. This dual approach enhances accuracy and ensures reliability in industrial environments. Experimental results show significant SDE reduction and improved signal quality, with the hybrid-grating design maintaining accuracy over a wider installation gap. These results, supported by MATLAB simulations and experimental data, demonstrate the potential benefits for industries requiring high-precision machinery. SDE reduction and mounting tolerance are addressed to enhance the design and application of optical linear encoders. The proposed innovations enhance the accuracy and reliability of optical linear encoder systems, offering practical solutions scalable for industrial applications. The presented work bridges theoretical modelling and practical implementation, providing valuable references for the next generation of high-precision optical linear encoders.
Doctoral dissertation readers can search via VILNIUS TECH Virtual Library.
