Real time interferometric ellipsometry with optical heterodyne and phase lock-in techniques.

Area of Science:

• Optics and Photonics
• Materials Science
• Surface Science

Background:

• Traditional ellipsometry often relies on mechanical components like compensators and quarter-wave plates.
• These moving parts can introduce systematic errors and limit measurement speed and accuracy.
• Accurate measurement of optical properties is crucial for characterizing and understanding metal surfaces.

Purpose of the Study:

• To develop and demonstrate a novel interferometric ellipsometer for measuring the optical properties of metal surfaces.
• To eliminate errors associated with moving optical elements in ellipsometric measurements.
• To achieve real-time and high-accuracy measurements of ellipsometric parameters Psi and Delta.

Main Methods:

• Integration of a Mach-Zehnder interferometer with an optical heterodyne system.
• Utilization of an Acousto-Optic (AO) modulator within the optical setup.
• Implementation of a phase lock-in technique coupled with computer processing for data acquisition.

Main Results:

• Successful establishment of an interferometric ellipsometer without mechanical moving parts.
• Elimination of errors typically caused by compensators and quarter-wave plates.
• Real-time and accurate measurement of ellipsometric parameters Psi (amplitude ratio) and Delta (phase difference).

Conclusions:

• The developed interferometric ellipsometer offers a robust and accurate method for characterizing metal surface optical properties.
• The absence of moving components significantly enhances measurement reliability and precision.
• This technique provides a valuable tool for real-time surface analysis in various scientific and industrial applications.