1/2 I still struggle getting used to the fact that the smallest mirrors of the Extremely Large Telescope are similar in size to the primary mirrors of many current telescopes!
The M5 – the fifth mirror in the optical path – has reached a key milestone: its blank, the piece that will be later polished, has been finalised.
2/2 This flat elliptical mirror measures 2.7 by 2.2 metres. It's the largest tip-tilt mirror in the world: it will move without bending about 10 times per second.
It will work together with the M4, a very fast deformable mirror, to correct perturbations caused by the telescope mechanisms, the wind and atmospheric turbulence.
@astro_jcm absolutely cannot get my head around a mirror that size tilting 10 times a second. Bonkers engineering. I remember getting a hold of a little CCD that had tip tilt adaptive optics as an undergrad, and that seemed like witchcraft.
@tehstu Likewise! I really like chatting with the engineers here when I have the chance. Sometimes I feel that the engineering problems they have to solve are more bonkers than the astrophysical problems we want to solve with the things they build 😅
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