Orbital angular momentum beam-based interferometry for an in-plane displacement measurement

Area of Science:

• Optics and Photonics
• Metrology
• Nanotechnology

Background:

• Interferometry is crucial for precise measurements.
• Orbital Angular Momentum (OAM) offers unique properties for optical applications.
• Existing methods may lack robustness or resolution for certain displacement measurements.

Purpose of the Study:

• To propose a novel interferometry system for in-plane displacement measurement.
• To leverage Orbital Angular Momentum (OAM) for enhanced measurement capabilities.
• To develop a robust and high-resolution displacement sensing technique.

Main Methods:

• Utilizing a vortex beam (VB) incident on a diffraction grating.
• Interfering ±1st order diffraction beams with conjugate OAM.
• Demodulating the resulting petal-like interferogram to determine displacement.

Main Results:

• Theoretical analysis: 1° interferogram rotation corresponds to 2.31 nm displacement.
• Experimental validation: Maximum measurement error below 3.35%.
• Demonstrated robustness against environmental disturbances.

Conclusions:

• The proposed OAM-based interferometry system provides a novel and robust method for in-plane displacement measurement.
• The system combines advantages of OAM and grating interferometry, using grating pitch as a reference for high resolution and stability.
• This technique offers a promising solution for precise metrology in demanding environments.