Two-step spatial phase-shifting radial shearing interferometery with circular gratings

Area of Science:

• * Optics and Photonics
• * Wavefront Sensing and Metrology

Background:

• * Interferometry is crucial for precise optical measurements.
• * Measuring wavefront phase derivatives is essential for optical system characterization and aberration analysis.

Purpose of the Study:

• * To present a simple radial shearing interferometry system for measuring the radial first-order derivative of arbitrary wavefront phase.
• * To demonstrate a two-step phase-shifting algorithm for accurate phase retrieval from interferograms.

Main Methods:

• * Utilized circular gratings for radial shearing interferometry.
• * Developed a system to simultaneously obtain two spatial phase-shifted radial shearing interferograms.
• * Implemented a two-step phase-shifting algorithm with arbitrary phase-shift values for phase retrieval.

Main Results:

• * Successfully measured the radial first-order derivative of spherical wavefront phase, validating the system's feasibility and accuracy.
• * Applied the optical system to measure the wavefront phase derivative of a propane flame under plane incident wave conditions.

Conclusions:

• * The proposed radial shearing interferometry with circular gratings offers a simple and effective method for wavefront phase derivative measurement.
• * The technique is versatile, applicable to various wavefront types and potentially useful in fields like fluid dynamics and plasma diagnostics.