Measuring seeing with a Shack-Hartmann wave-front sensor during an active-optics experiment

Area of Science:

• Astronomy
• Optical Engineering
• Atmospheric Physics

Background:

• Accurate measurement of atmospheric seeing is crucial for astronomical observations.
• The Large Sky Area Multi-Object Fiber Spectroscopic Telescope (LAMOST) requires precise active optics for optimal performance.
• Previous seeing measurements may not have been integrated with active optics systems.

Purpose of the Study:

• To measure atmospheric enclosure seeing over a 120-m path using a Shack-Hartmann wave-front sensor (S-H WFS) within the LAMOST active-optics experiment.
• To validate the accuracy of S-H WFS seeing estimates against established metrics.
• To inform strategies for mitigating the impact of poor seeing conditions on astronomical observations.

Main Methods:

• Utilized a Shack-Hartmann wave-front sensor (S-H WFS) for differential image motion measurement.
• Conducted measurements along a 120-m light path in the LAMOST outdoor active-optics experiment.
• Analyzed seeing estimates in conjunction with refractive-index structure constants and active optics precision.

Main Results:

• Demonstrated the first-time use of S-H WFS for measuring atmospheric enclosure seeing in the LAMOST system.
• S-H WFS seeing estimates showed strong agreement with actual atmospheric seeing conditions.
• Seeing measurements correlated well with refractive-index structure constant estimates and active optics performance metrics.

Conclusions:

• The Shack-Hartmann wave-front sensor is a reliable tool for measuring atmospheric seeing in astronomical telescope systems.
• Accurate seeing measurements are essential for optimizing active optics performance in large telescopes like LAMOST.
• The study provides a foundation for developing and implementing countermeasures against adverse seeing conditions.