A full Stokes vector ellipsometry measurement system for in situ diagnostics in dynamic experiments.

Area of Science:

• Physics
• Materials Science
• Optical Engineering

Background:

• Dynamic experiments require high temporal resolution for accurate optical property measurements.
• Traditional ellipsometry systems lack the speed to capture rapid material changes.

Purpose of the Study:

• To develop a fast ellipsometry system capable of measuring all four Stokes parameters with nanosecond resolution.
• To demonstrate the system's utility in dynamic experiments like fast foil heating and shock compression.
• To characterize the optical properties of nickel and 1020 steel under extreme conditions.

Main Methods:

• Development of a high-speed ellipsometry system with nanosecond temporal resolution.
• Simultaneous measurement of all four Stokes parameters.
• Application of the system to fast foil heating experiments on nickel.
• Application of the system to shock compression experiments on 1020 steel.

Main Results:

• Measured the complex index of refraction and emissivity of nickel between 1000-1900 K at 532 nm.
• Observed a monotonous increase in nickel emissivity below and above its melting point, with a 2% jump at the phase transition.
• Recorded significant changes in optical properties of 1020 steel under shock compression up to 25 GPa, with emissivity doubling.
• Demonstrated the system's capability for sample-free surface measurements under shock compression.

Conclusions:

• The developed fast ellipsometry system is effective for dynamic optical measurements.
• The system accurately captured emissivity changes in nickel during phase transitions.
• Significant optical property changes occur in steel under shock compression, as evidenced by doubled emissivity.