It has been polished somewhere in the period 1940-1945, by a French astronomer (name forgotten) from the Société d'Astronomie
Populaire in Toulouse. At this time my grandfather was living in the countryside, and there were strong food
restrictions due to the German occupation. I have been told that the mirror was paid with two big cheeses (Roquefort) !
End of 2008 I sent the mirror to JM Lecleire from Astrotelescope. A new aluminium coating (high reflectivity) was deposited, and the
mirror was controlled. I was lucky since JM Lecleire stopped his activities 2 weeks after I received back my mirror.
The mirror is quite thick; it is made of St Gobain glass and thus some care must be taken to thermalize it before using the telescope.
The Peak to Valley surface accuracy was measured in two orthogonal directions : lambda/19 and lambda/54 (values that should be
compared to the measurement accuracy, but I don't know it). The star test shows no astigmatism.
By contrast, the surface quality is not so good : a lot of very tiny scratches, plus one big.
There is also a significant microroughness, visible with the phase contrast pictures.
With eye observation the images are beautifully sharp, so I will only change it for a significantly larger diameter :-).
Foucault test, picture taken during mirror characterisation
Summary of mirror characterisation
Star test showing no astigmatism
Phase contrast test showing surface micro-roughness (qualitative test)
Secondary mirror
I bought it from Astam, around 1995-1997. If I remember well the announced surface quality was
lambda/8 rms. This makes lambda/4 for the wavefront, not extraordinary I acknowledge...
It has a standard protected aluminium coating.
The small axis is 45mm, which gives an obstruction ratio of 0.27.
