Validation of delay dispersion estimation for coherence imaging spectroscopy.

Area of Science:

• Physics
• Plasma Physics
• Optical Diagnostics

Background:

• Coherence Imaging Spectroscopy (CIS) is a camera-based polarization interferometry technique.
• CIS provides high-resolution 2D spectroscopic measurements, commonly used in fusion plasma diagnostics.
• Accurate characterization of delay dispersion is essential for deriving physics-relevant quantities from CIS data.

Purpose of the Study:

• To validate delay dispersion estimation methods for Coherence Imaging Spectroscopy (CIS).
• To assess methods for wavelength ranges inaccessible to conventional calibration sources.
• To evaluate the impact of system hardware on estimation precision.

Main Methods:

• Validation of extrapolation and interpolation methods for delay dispersion estimation.
• Utilized simulation of system response and power-law fits of measurements.
• Employed two tunable lasers (450-750 nm) and tested three different CIS systems.

Main Results:

• The simplest CIS setup achieved the lowest deviation (<2%) between estimated and measured delay dispersion.
• More complex CIS systems showed deviations up to 20%, with spatial structures impacting accuracy.
• Crystal alignment and lens quality significantly influence estimation precision.

Conclusions:

• Extrapolation and interpolation methods can effectively estimate CIS delay dispersion, especially for challenging wavelength ranges.
• Simpler CIS system designs are less prone to hardware imperfections, leading to more precise delay dispersion estimations.
• The study highlights the importance of hardware quality and alignment in accurate CIS diagnostic data interpretation.