SIM PlanetQuest white-light fringe modeling: picometer accuracy calibration and estimation algorithms.

Area of Science:

• Astronomy and Astrophysics
• Optical Interferometry
• Precision Measurement

Background:

• SIM PlanetQuest requires microarcsecond astrometry accuracy, necessitating picometer-level optical path difference measurements.
• Accurate modeling and calibration of white-light fringes are critical challenges for starlight interferometry.
• Previous CCD-pixel-level calibration schemes are inadequate due to wavefront aberrations causing significant phase-dispersion variations.

Purpose of the Study:

• To develop an improved white-light fringe model accounting for wavefront aberrations.
• To create a robust calibration and estimation scheme for resolving pixel bandwidth.
• To validate the new method using simulated and experimental data.

Main Methods:

• Developed a white-light fringe model incorporating extra phase dispersions from wavefront aberrations.
• Implemented a calibration and estimation scheme utilizing long-stroke fringe measurements.
• Validated the algorithm with simulated data and experimental data from the Spectral Calibration Development Unit (SCDU).

Main Results:

• Simulated data showed total systematic errors in the calibration and estimation scheme below 1 picometer.
• Experimental data from SCDU demonstrated an end-to-end accuracy better than 20 picometers.
• Achieved SIM PlanetQuest Engineering Milestone 4, validating the algorithm's performance.

Conclusions:

• The novel white-light fringe model and calibration scheme effectively address challenges posed by wavefront aberrations.
• The developed method provides picometer-level accuracy, essential for future high-precision astrometry missions.
• The successful validation confirms the algorithm's readiness for SIM PlanetQuest.