Simple phase-shifting method in a wedge-plate lateral-shearing interferometer

Area of Science:

• Optical Engineering
• Interferometry
• Metrology

Background:

• Phase-shifting interferometry is crucial for precise optical measurements.
• Traditional methods often require complex setups and precise control of microscopic movements.
• Wedge-plate interferometers offer a unique approach to lateral shearing.

Purpose of the Study:

• To introduce a simplified phase-shifting technique for wedge-plate lateral shearing interferometry.
• To demonstrate a method that enhances precision in phase shift control.
• To reduce the complexity and moving distance requirements compared to existing methods.

Main Methods:

• Utilizing a wedge plate in a lateral shearing interferometer.
• Implementing phase shifts by moving the wedge plate in an in-plane parallel direction.
• Leveraging the non-constant thickness of the wedge plate along its wedge direction.

Main Results:

• Achieved required phase shifts for interferometry by simple linear translation of the wedge plate.
• Demonstrated that the required moving distance is on the order of millimeters, significantly less than wavelength-scale movements.
• Showcased superior precision in controlling the moving distance compared to piezoelectric transducer methods.

Conclusions:

• The described method offers a simple and precise approach to phase shifting in wedge-plate lateral shearing interferometry.
• This technique simplifies experimental setups by requiring only one additional linear translator.
• The reduced moving distance and enhanced precision make it a valuable advancement for optical metrology.