A New Image Grating Sensor for Linear Displacement Measurement and Its Error Analysis.

Area of Science:

• Metrology
• Optical Measurement Systems
• Image Processing

Background:

• Vision-based systems are crucial for linear displacement measurement.
• Existing methods face challenges in accuracy over large ranges.
• Need for enhanced precision in displacement sensing.

Purpose of the Study:

• To develop a novel image grating system for high-accuracy, large-range linear displacement measurement.
• To improve upon the limitations of current vision-based measurement techniques.
• To achieve sub-micrometer accuracy and high repeatability.

Main Methods:

• Utilized a patterned glass plate and an ultra-low distortion lens.
• Employed a DFT local up-sampling phase correlation method for sub-pixel translation detection.
• Implemented multiple stripe patterns and dynamic calibration for nonlinear error compensation.

Main Results:

• Achieved a total measurement error of less than 2.5 μm over a 60 mm range.
• Demonstrated high repeatability within 0.16 μm (standard deviation).
• Successfully compensated for nonlinear errors through dynamic pixel equivalent calibration.

Conclusions:

• The proposed image grating system significantly enhances linear displacement measurement accuracy and range.
• The system offers a robust solution for applications requiring precise motion tracking.
• Error compensation strategies are vital for achieving sub-micrometer precision in optical metrology.