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High-order diffraction gratings with an isosceles triangle profile for a nano-precision linear optical encoder.
Optics Letters
|December 1, 2025
Summary
A novel high-order diffraction grating enhances nanoscale displacement measurement. This grating achieves over 40% diffraction efficiency, improving positioning accuracy and stability for linear optical encoders.
Area of Science:
- Optics
- Nanotechnology
- Materials Science
Background:
- Linear optical encoders are crucial for precise motion control.
- High-order diffraction offers potential for enhanced measurement resolution.
- Limited diffraction efficiency in high orders has been a key challenge.
Purpose of the Study:
- To propose and demonstrate a high-order diffraction grating with improved efficiency.
- To achieve high-precision nanoscale displacement measurement using this grating.
- To analyze the performance metrics of the proposed grating system.
Main Methods:
- Design of a diffraction grating with an isosceles triangle profile.
- Fabrication using anisotropic etching of silicon (100) and replication.
- Experimental interference of ±4th order diffracted beams for optical subdivision.
Main Results:
- Achieved over 40% diffraction efficiency at the ±4th order.
- Demonstrated positioning accuracy of 37.1 nm over 1 mm travel length.
- Reported repeatability of 3.7 nm and stability of 3.6 nm (@ 60 s).
Conclusions:
- The proposed isosceles triangle profile grating significantly enhances high-order diffraction efficiency.
- This advancement enables superior nanoscale displacement measurement capabilities.
- The developed grating is suitable for high-precision linear optical encoder applications.
