Interferometric phase reconstruction by nonuniform shifting of the reference beam

Area of Science:

• Optics and Photonics
• Interferometry
• Phase Measurement Techniques

Background:

• Common-path interferometers offer stability but often require uniform phase across the reference beam for accurate measurements.
• Existing phase reconstruction algorithms like Carré and Hariharan have limitations regarding phase uniformity.
• Novel methods are needed to overcome these limitations for broader applicability.

Purpose of the Study:

• To present a novel method for phase measurement in common-path interferometers.
• To demonstrate that phase reconstruction algorithms can be used without requiring uniform phase across the reference beam.
• To validate the technique through experimental and simulation results.

Main Methods:

• Utilizing phase reconstruction algorithms (Carré, Hariharan) that only require consistent phase step ratios per pixel.
• Implementing phase measurement by shifting the tilt or focus of the reference wavefront.
• Conducting a proof-of-principle experiment with a scatterplate interferometer and tilt phase-shifting.
• Performing computer simulations using defocus shifting for validation.

Main Results:

• Successful phase measurement and reconstruction in a common-path interferometer.
• Demonstration of the technique using both tilt and defocus shifting of the reference wavefront.
• Experimental validation of reflected phase measurement for an optical element.
• Mathematical validity confirmed through computer simulations.

Conclusions:

• A novel and effective method for phase measurement in common-path interferometers has been developed.
• The technique relaxes the stringent requirement of uniform phase across the reference beam.
• This approach broadens the applicability of phase reconstruction algorithms in interferometric measurements.