Pinhole-free point-diffraction dynamic phase imaging using focused white-light Sagnac interferometry.

Area of Science:

• Optics and Photonics
• Interferometry
• Phase Imaging

Background:

• Quantitative Phase Imaging (QPI) is crucial for analyzing transparent samples.
• Traditional methods often require pinholes or complex setups, limiting throughput and stability.
• Developing robust, high-sensitivity, single-shot QPI techniques remains an active research area.

Purpose of the Study:

• To present a novel convergent-beam white-light Sagnac interferometer for single-shot QPI.
• To achieve point-diffraction-like interference without a pinhole.
• To demonstrate a robust and high-throughput platform for transparent sample analysis.

Main Methods:

• Utilized a convergent-beam white-light Sagnac interferometer configuration.
• Introduced a sample at the focal plane to asymmetrically modify counter-propagating beams.
• Employed a Michelson-type replicator for single-shot capture of phase-shifted interferograms using a color CMOS sensor.

Main Results:

• Generated point-diffraction-like interference without a pinhole.
• Achieved single-shot quantitative phase imaging with common-path stability and broadband compatibility.
• Successfully retrieved static and dynamic phase distributions in thin films, alcohol evaporation, and candle flames.
• Identified the green channel of the CMOS sensor as most reliable for phase retrieval.

Conclusions:

• The developed Sagnac interferometer offers a robust platform for single-shot, high-sensitivity QPI.
• The pinhole-free design enhances stability and throughput.
• This technique is applicable to various transparent samples, including dynamic processes.