Wide-field optical design for a 60 m submillimeter telescope

Area of Science:

• Astronomy and Astrophysics
• Optical Engineering
• Telescope Design

Background:

• Submillimeter telescopes are crucial for observing the cold universe.
• Existing designs often face limitations in field of view and optical performance.
• A large-aperture telescope is under conceptual design in China.

Purpose of the Study:

• To present a practical wide-field optical design for a 60 m aperture submillimeter telescope.
• To achieve a 1° field of view (FOV) for efficient detector pixel feeding.
• To ensure high optical performance across the entire FOV.

Main Methods:

• Designed an F/6 Ritchey Chrétien (RC) optical system.
• Incorporated a quasi-planar tertiary corrector to eliminate aberrations.
• Utilized a silicon wedge prism for flat and telecentric focal planes in subfield instruments.

Main Results:

• The design cancels spherical, coma, and astigmatism aberrations.
• Achieved a balance in mirror sizes, central obscuration, and focal-plane curvature.
• Demonstrated Strehl ratios above 0.85 across the 1° FOV for over 10^5 detector pixels at 0.65 mm.

Conclusions:

• The proposed optical design is practical for a 60 m submillimeter telescope.
• The design enables efficient and uniform illumination of a large number of detector pixels.
• Addresses key challenges in wide-field optical design for submillimeter astronomy.