Approach based on χ² to phasing segmented-mirror telescopes using multiple wavelengths: data reduction, wavelength...

Area of Science:

• Astronomy and Astrophysics
• Optical Engineering

Background:

• Extremely Large Telescopes (ELTs) require precise phasing of segmented mirrors for optimal performance.
• Existing interferometric techniques for ELT phasing often rely on multiwavelength measurements but lack a unified optimization framework.
• Achieving large capture ranges (microns) and low error rates is critical for successful on-sky phasing.

Purpose of the Study:

• To present a novel chi-squared (χ²) based framework for obtaining intersegment edge heights from multiwavelength data.
• To demonstrate a method for selecting optimal wavelengths to maximize capture range and minimize phasing errors for ELTs.
• To account for wavelength uncertainties introduced by finite-width interference filters in real-world phasing scenarios.

Main Methods:

• Development of a χ²-based data analysis framework applicable to various phasing techniques.
• Optimization of wavelength selection to enhance the capture range and reduce error rates for ELT phasing.
• Inclusion of wavelength uncertainty analysis due to interference filter characteristics.

Main Results:

• The proposed framework effectively determines intersegment edge heights using multiwavelength data.
• Demonstrated ability to select optimal wavelength sets that significantly improve phasing performance.
• Validation of the method with real-world data from the Keck 2 telescope using three-wavelength phasing.

Conclusions:

• The χ²-based framework provides a robust and adaptable approach for ELT phasing.
• Optimal wavelength selection is crucial for maximizing capture range and achieving required accuracy.
• The method is validated and applicable for current and future ELT construction and operation.