Wavefront sensing

Using the ALFOSC WFS setup a lot of data has been acquired but it has been found difficult to interpret the results. Attempts to apply corrections based on the ALFOSC WFS results have not been successful.

Using the analysis tools for the image quality database which provide ellipticity, position angle and seeing for all the individual images we have looked at the applied active optics astigmatism correction and the resulting ellipticity and position angle, where the proper corrections should produce images with a random distribution of position angles with small ellipticity amplitudes. However, results on different occasions are not consistent.

It is currently unclear how to proceed, also because we do not really have in-house expertise to study this problem in more depth.