Simultaneous thickness and phase index measurements with a motion-free actively tunable Twyman-Green interferometer

Area of Science:

• Optical metrology
• Interferometry
• Thin film characterization

Background:

• Traditional Twyman-Green interferometers rely on mechanical components for measurements.
• Accurate determination of sample thickness and refractive index is crucial in various scientific and industrial applications.
• Existing methods can be complex, time-consuming, or lack precision.

Purpose of the Study:

• To develop a novel, electronically tunable Twyman-Green interferometer.
• To enable simultaneous measurement of thickness and refractive index of parallel plate samples.
• To eliminate bulk mechanical motion for improved repeatability and potential miniaturization.

Main Methods:

• An electronically tunable focus lens was integrated into a classical Twyman-Green interferometer setup.
• A theoretical model was developed to calculate sample parameters from interferometric data.
• Experimental validation was performed to demonstrate the system's efficacy.

Main Results:

• The proposed interferometer configuration successfully measured sample thickness and refractive index.
• The system demonstrated high repeatability and accuracy.
• Elimination of bulk mechanical motion was achieved through electronic control.

Conclusions:

• The electronically tunable Twyman-Green interferometer provides a robust and accurate method for optical metrology.
• The absence of mechanical parts allows for potential miniaturization and enhanced stability.
• This technique offers a promising advancement for non-contact, high-precision material characterization.