Creating space-telescope quality images with EST

Most of the time, turbulence in the Earth's atmosphere makes it difficult to obtain high-quality, crisp solar images. Dr. Matthew Townson, from Durham University, tell us about adaptive optics for obtaining better images with telescopes and how EST is going to implement and improve this system.

Image with no adaptive optics (AO) filter, a conventional AO filter, and the new AO filter being developed for EST (left to right).  Credit: von der Lühe et al, 2005, Comptes Rendus Phys, 6(10), 1139.

Turbulence in the Earth’s atmosphere frequently degrades image resolution from ground-based telescopes [left image]. To correct this effect highly sophisticated instrumentation known as adaptive optics (AO) is used.

Typically, AO only corrects for turbulence in a small area of an image [middle image]. In contrast, the European Solar Telescope (EST) will be fitted with an adaptive optics system that will correct a wider field of view, to create high resolution images across significantly larger areas of the solar surface. These high resolution wide-field images will allow us to better understand the dynamics occurring on the Sun at both large and small scales [right image].

Correcting for the atmosphere across a wider field of view requires in-depth understanding of: the complex turbulence layers within the Earth’s atmosphere; where the turbulence is occurring within the atmosphere; and how to perform the correction.

In Durham, we use a variety of instruments to locate and measure the strength of turbulence, during both day and night. This knowledge will allow us to build a picture of typical atmospheric conditions, which enables us to identify the best location for European Solar Telescope and to tune the adaptive optics system to give the highest resolution images possible.

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