Angular anisoplanatism in non-Kolmogorov turbulence over horizontal paths

Area of Science:

• Astronomy and Astrophysics
• Optical Engineering
• Atmospheric Science

Background:

• Anisoplanatic error degrades imaging quality in astronomical observations and optical systems.
• Understanding anisoplanatism is crucial for long-baseline imaging and adaptive optics.
• Non-Kolmogorov turbulence models with finite outer scales are more realistic for certain atmospheric conditions.

Purpose of the Study:

• To derive generalized expressions for piston-removed and piston-and-tilt-removed anisoplanatic error.
• To investigate anisoplanatic error behavior in non-Kolmogorov turbulence over long horizontal paths.
• To quantify the impact of outer scale and power law on anisoplanatic error.

Main Methods:

• Application of Mellin-transform techniques to derive analytical expressions.
• Evaluation of derived expressions for anisoplanatic error.
• Analysis of error behavior concerning scene angular extent and isoplanatic angle.

Main Results:

• Generalized expressions for anisoplanatic error were derived for non-Kolmogorov turbulence with a finite outer scale.
• Anisoplanatic error was found to saturate at values less than 1 radian squared in many scenarios.
• Piston and tilt contributions become dominant as the power law increases.
• The outer scale size significantly influences piston and tilt terms.

Conclusions:

• Removing piston and tilt aberrations can reduce anisoplanatism by up to 60%.
• The findings are particularly relevant for imaging long horizontal paths with large angular scene extents.
• The study highlights the importance of considering outer scale and power law in turbulence models.