研究目的
To develop and test a portable instrument for measuring atmospheric turbulence seeing profiles at solar astronomical sites, using the Advanced Multiple Aperture Seeing Profiler (A-MASP) concept with proof-of-concept observations.
研究成果
The proof-of-concept A-DASP instrument successfully measured atmospheric turbulence seeing profiles at the DST site, identifying multiple turbulence layers and their evolution. Results are consistent with theoretical models, demonstrating the feasibility of portable seeing profilers for astronomical site characterization. Future work should address limitations in ground-layer measurement and improve portability for site surveys.
研究不足
The instrument with two sub-apertures differs from a real A-MASP using separate telescopes, particularly in measuring turbulence at altitude h=0. Assumptions include thin turbulence layers, no correlation between layers, Kolmogorov theory with infinite outer scale, and stable turbulence during measurements. Vertical resolution decreases with altitude, and high-altitude turbulence layers are measured with lower precision.
1:Experimental Design and Method Selection:
The experiment used the A-DASP (Advanced Dual Aperture Seeing Profiler) principle, which involves using two sub-apertures (simulated with a pupil mask on a large telescope) and multiple regions of interest (ROIs) on the solar surface to measure turbulence profiles. The method is based on slope detection and cross-correlation techniques to retrieve the Fried parameter and turbulence strength at different altitudes.
2:Sample Selection and Data Sources:
Observations were conducted at the Dunn Solar Telescope (DST) of the National Solar Observatory from July 12-14, 2017. Data consisted of image sequences of the solar surface, with ROIs selected in linear alignment to emulate guide stars.
3:Data consisted of image sequences of the solar surface, with ROIs selected in linear alignment to emulate guide stars.
List of Experimental Equipment and Materials:
3. List of Experimental Equipment and Materials: Equipment included the DST telescope, a pupil mask with two sub-apertures, wedge prisms, a narrow-band filter (6302 ? center wavelength, 3.8 ? bandwidth), relay optics, and an Andor Zyla 5.5 sCMOS camera. Materials involved stainless-steel masks and optical components for beam splitting and imaging.
4:8 ? bandwidth), relay optics, and an Andor Zyla 5 sCMOS camera. Materials involved stainless-steel masks and optical components for beam splitting and imaging.
Experimental Procedures and Operational Workflow:
4. Experimental Procedures and Operational Workflow: The setup involved placing the instrument behind the telescope's adaptive optics output. Images were captured with an exposure time of 3 ms, using the camera in 2x2 binning mode. Multiple bursts of 1000-2000 images were taken over several days, with dark and flat-field corrections applied. ROIs of 30x30 pixels were used for cross-correlation to determine position shifts.
5:Data Analysis Methods:
Data analysis involved normalized cross-correlation to calculate image shifts, bi-cubic interpolation for sub-pixel precision, and solving equations to derive turbulence parameters (e.g., Fried parameter r0 and C_n^2) using theoretical models based on Kolmogorov turbulence.
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