Co-focus control of segmented primary mirror telescopes based on segmented mirror pose detection.

Area of Science:

• Optical Engineering
• Astronomy
• Control Systems

Background:

• Segmented primary mirrors are crucial for large astronomical telescopes.
• Maintaining co-focus and alignment of these segments is essential for optimal performance.
• Existing control methods face challenges with environmental variations like temperature fluctuations.

Purpose of the Study:

• To develop and validate a novel co-focus closed-loop control method for segmented primary mirrors.
• To enhance the stability and precision of astronomical telescope focal spots.
• To enable long-term confocal maintenance during continuous telescope operation.

Main Methods:

• Pose estimation using a pose estimation matrix to calculate segment pose changes.
• Pose-to-actuation mapping matrix to compute required segment actuation values.
• Parameter analysis of noise characteristics in a four-segmented mirror system.
• Experimental validation on a subsystem of the LAMOST primary mirror.

Main Results:

• The proposed method accurately calculates pose changes and actuation values.
• Parameter analysis identified system noise characteristics.
• Experimental results show focal spot convergence within 0.1 arcsec.
• The control method demonstrated robustness against temperature variations exceeding 12°C.

Conclusions:

• The developed co-focus closed-loop control method is effective for segmented primary mirrors.
• The method ensures precise and stable focal spot maintenance.
• This technique is vital for the long-term operational stability of large astronomical telescopes.