Mach-Zehnder interferometry at framing rates of 10.5-21 GHz

Area of Science:

• * Plasma Physics
• * Optics
• * Laser Technology

Background:

• * Accurate measurement of plasma properties requires high-resolution diagnostic techniques.
• * Traditional interferometry methods can be limited by temporal resolution and complexity.

Purpose of the Study:

• * To develop a simple, high-speed optical diagnostic system for analyzing laser-irradiated plasma.
• * To achieve jitter-free, multi-frame interferometry for capturing dynamic plasma events.
• * To enable precise measurement of electron density in plasmas.

Main Methods:

• * A simple beam splitter divides a single ultrashort optical pulse into four beams with known jitter-free delay.
• * A Mach-Zehnder interferometer is employed to generate four interferograms in a single shot.
• * Precise overlapping of reference and scene beams on film achieves high fringe quality (<1/10 wave error).

Main Results:

• * Four interferograms of CO(2) laser-irradiated plasma were successfully recorded with a 95 ps interframe delay.
• * High fringe quality was maintained, allowing detection of fractional fringe shifts in plasmas up to 5 x 10^18 cm^-3 electron density.
• * The system provided immediate results on Polaroid-type 667 film, eliminating the need for streak cameras or wavelength filters.

Conclusions:

• * The developed method offers a simple and effective approach for high-speed plasma diagnostics.
• * The technique allows for flexible framing rates of 10.5 or 21.0 GHz by rearranging optical components.
• * This diagnostic tool is crucial for understanding transient phenomena in laser-produced plasmas.