Parallel two-step spatial carrier phase-shifting common-path interferometer with a Ronchi grating outside the Fourier...

Area of Science:

• Optical Physics and Metrology
• Quantitative Phase Imaging
• Interferometry

Background:

• Quantitative phase imaging (QPI) is crucial for label-free biological and materials science research.
• Traditional interferometers can be sensitive to environmental vibrations, limiting their stability and applicability.
• Existing QPI methods often require multiple sequential measurements, increasing acquisition time and potential for error.

Purpose of the Study:

• To propose and validate a novel parallel two-step spatial carrier phase-shifting common-path interferometer.
• To enable simultaneous capture of phase-shifted interferograms for efficient and stable QPI.
• To demonstrate the system's capability for accurate phase reconstruction of specimens.

Main Methods:

• A common-path interferometer design utilizing a Ronchi grating placed outside the Fourier plane.
• Simultaneous acquisition of two phase-shifted interferograms with a spatial carrier.
• Phase reconstruction via subtraction of interferograms to eliminate the dc term, followed by Fourier transform analysis.

Main Results:

• Successful simultaneous capture of two phase-shifted interferograms was achieved.
• The subtraction method effectively eliminated the dc term, simplifying phase calculation.
• Experimental validation using a phase plate demonstrated the interferometer's validity and stability for quantitative phase measurement.

Conclusions:

• The proposed parallel two-step spatial carrier phase-shifting common-path interferometer offers a robust and efficient solution for QPI.
• The system's common-path design enhances stability, making it suitable for demanding applications.
• This technique provides a reliable method for precise phase reconstruction of microscopic specimens.