Figure 31 shows a sample pair of long exposure images, which compare images before and after deconvolution. The top row shows the AO corrected red wing images captured within a few seconds of each other but during vastly different seeing conditions. The image on the right was recorded with a Fried parameter r0 = 16.5 cm and a Strehl of S = 0.88. The image on the left has a significantly lower Strehl of S = 0.46 and was recorded at r0 = 5.4 cm. The high spatial frequency information is still present in the poor seeing image on the left but the contrast is reduced significantly and the image appears “soft”. The corresponding deconvolved images are displayed at the bottom row of Figure 31. The deconvolution process clearly enhances the contrast of the poor seeing image close to the level of the restored high Strehl image. The power spectra of these images are shown in Figure 32. The restored PSDs closely match each other throughout the frequency range.
The top row of Figure 33 displays the velocity maps obtained from the two sets of unprocessed blue and red wing pairs, the first (left) captured during different seeing conditions and the second (right) set during very good seeing conditions. The bottom row of the figure displays the velocity maps obtained from the deconvolved wing images. The dopplergram produced from raw filtergrams exhibits severe intensity-velocity crosstalk. In particular, velocities measured in the sunspot umbra display the resulting artifacts and spurious velocities. Deconvolution of the wing images significantly reduces intensity-velocity crosstalk.
Rimmele and Marino (2006) give an example of science results achieved by deploying PSF estimation and post-facto deconvolution. In general, quantitative analysis of AO data can be significantly improved by applying post-facto deconvolution techniques even in the case of long exposures. At present, solar astronomers are very familiar with and heavily apply post-facto reconstruction to short exposure images and do so with much success.
Living Rev. Solar Phys. 8, (2011), 2
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