Dual displacement resolution encoder by integrating single holographic grating sensor and heterodyne interferometry

Area of Science:

• Optics and Photonics
• Metrology
• Nanotechnology

Background:

• Accurate displacement measurement is crucial for advanced manufacturing and scientific research.
• Existing encoders often face limitations in resolution, sensitivity, or environmental robustness.
• Integrating multiple sensing principles can potentially overcome these limitations.

Purpose of the Study:

• To develop a novel encoder with dual displacement resolution capabilities.
• To enhance measurement sensitivity and precision beyond current standards.
• To create a robust system resistant to environmental disturbances.

Main Methods:

• Integration of a multiple-grating-scale holographic displacement sensor with a heterodyne interferometer.
• Utilizing two effective grating pitches (0.41 μm and 10.62 μm) for dual-resolution measurements.
• Experimental validation of the encoder's performance.

Main Results:

• Achieved theoretical sensitivities of 0.9 °/nm and 0.036 °/nm.
• Demonstrated best resolutions of 0.3 pm and 7.4 pm.
• Exhibited displacement errors better than 0.2% for 1 mm measurements.
• Experimental results confirmed high sensitivity, high resolution, and environmental stability.

Conclusions:

• The proposed dual-resolution encoder offers significant advancements in displacement metrology.
• The integrated system provides superior precision and robustness compared to conventional methods.
• This technology has potential applications in high-precision positioning and measurement systems.