Four-mirror flat-field anastigmat aplanat telescopes with simple closed-form solutions

Area of Science:

• Optical Engineering
• Astronomy Instrumentation
• Telescope Design

Background:

• Anastigmat aplanat telescopes are crucial for advanced optical systems.
• Previous designs faced challenges in achieving flat image fields and aberration correction.

Purpose of the Study:

• To propose a novel four-mirror anastigmat aplanat telescope design.
• To achieve a flat image field and correct optical aberrations using specific mirror configurations.

Main Methods:

• Utilizing a Gregorian-form Mersenne afocal telescope as a feeder.
• Employing a concentric spherical Schwarzschild objective.
• Adjusting mirror radii ratios and tertiary conic (K3) to correct aberrations.

Main Results:

• A flat image field is achievable through mirror radii adjustment.
• Spherical aberration is corrected by the tertiary mirror without impacting coma or astigmatism.
• Minimum obscuration ratio determined to be 44.7% (20% by area).

Conclusions:

• The proposed four-mirror design offers a viable solution for aberration-corrected, flat-field telescopes.
• This design demonstrates effective aberration control through careful optical element specification.
• The minimized obscuration ratio makes it suitable for various astronomical applications.