Making a 33 cm f4.8 mirror on the Mirror-o-Matic 7: testing for astigmatism with Bath interferometer

It is important that there's no relevant astigmatism in the mirror before starting figuring. For that I use the Bath interferometer. If there's any relevant astigmatism present - for me more then about 1/15 lamda P-V wavefront, it should be removed first

[@kpv19741]

Впечатляет.