Rotating axis measurement based on rotational Doppler effect of spliced superposed optical vortex.

Area of Science:

• Optics and Photonics
• Metrology
• Applied Physics

Background:

• Traditional rotational Doppler effect (RDE) measurements require precise alignment of the optical axis with the object's rotating axis, which is challenging in practical applications.
• Misalignment significantly degrades signal quality and limits the accuracy of rotation detection in fields like manufacturing and scientific experiments.
• Determining the azimuth of the rotating axis is crucial for accurate RDE measurements but remains an unresolved problem.

Purpose of the Study:

• To develop a novel scheme for determining the rotating axis position using a single rotational Doppler effect measurement.
• To enhance the efficiency and accuracy of rotation detection in scenarios where optical and rotating axes are misaligned.
• To introduce a new structured optical beam capable of sensitive detection of rotating axis position.

Main Methods:

• Utilizing a novel superposed vortex beam with multiple topological charges, termed spliced superposed optical vortex (SSOV).
• Analyzing the RDE mechanism of the SSOV beam through mode decomposition and conservation laws of angular momentum and energy.
• Conducting a proof-of-concept experiment to validate the method across eight distinct azimuth ranges.

Main Results:

• Demonstrated a new method for determining rotating axis position with a single RDE measurement, significantly improving efficiency.
• Revealed the RDE mechanism of the SSOV beam, explaining its sensitivity to rotating axis position due to asymmetrical defects.
• Successfully conducted proof-of-concept experiments validating the method's effectiveness in detecting object's rotating axis position.

Conclusions:

• The proposed SSOV beam and RDE scheme offer a robust solution for determining rotating axis position, overcoming alignment challenges.
• The method's sensitivity and efficiency open new possibilities for optical manipulation, communication, remote sensing, and precision manufacturing.
• A pre-correction method for SSOV beams was developed to mitigate far-field propagation effects, further enhancing practical applicability.