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Bravo Fabio!
I'd say you have a nice one “mano” light and effective, because you did a good job of not easy, cautious positive progression, greatly improving the P / V ratio. So with yourself 32 nanometer error, also the bord rabattus I don't think will be of great disturbance to the star test.Thanks Giulio, but I would say that I was lucky and also thanks to your advice
e, Anyway, support…I took the last measurement after the concentrated retouching between the areas 4 e 5. I know, it's ridiculous:
This is much more realistic, in which I simulated 3 approximately mm of lowered edge:
If this were the case, it would still be a glass of decent workmanship that should satisfy my needs …”customer”.
We will see the behavior on the field!
Sincere congratulations, an excellent job! If you can make a rough look of the entire surface we can also evaluate the quality’ riduardo rugosita’ and general state of the surface, thus being able to exclude’ also any problems not visible to Foucault such as local errors and also understand the entity’ of the possible clinched edge.
A tip that comes to mind, in order to better evaluate the edge problem, is to blacken the caulk even with an indelible marker, that slightly attenuates its annoying and disturbing reflection, or to cover it with the external windows of the Couder mask well in contact with the mirror.
Another suggestion is to see with your software the Millier-La croix diagram which in practice is how the segments representing your areas are positioned, towards the “"trumpet bell"” of machining tolerances (which are loose in the center but very narrow at the edge).
Finally if you want read here an always interesting situation:
https://dobsoniani.forumfree.it/?t=68985880Unfortunately I never equipped myself to do Ronchi… I have to decide!
Col diagram M-L, simulating, as I said a bet on the lowered edge, I still have everything inside the horn with obviously a strong bet outside the zone “6” which would go beyond the 200%.
Estimating the size of the surface of the external crown I would say that, compared to the totality of the mirror (minus the shadow of the secondary), we would be around about the 5% of total light.
I would say that (always worth trying in the field) to the utmost: for planetary observations you can try diaphragming the primary slightly. For the Deep certainly all diameter.
Giulio, I tried to make another Foucault move to the area 5 masking the outermost part (about 3mm) of the lowered edge. I wanted to estimate better, in this way, the actual curvature of the area 5 and make sure , the name, that at least up to that diameter it was ok. Previous measures, as I said, of the area 5 they had been difficult because, in addition to diffraction, the lowered edge made a good part of the intensity area totally different from the rest: difficult to estimate the brightness of the center. Instead, it seems that the measurement of zone5 “masquerade” is well congruent with the rest of the surface. Therefore only the approximately 3mm ring would remain, residue of the previous form, already lowered. I think so “we will endure” so, with his 5% light….
And here is the moment of aluminizing:
I will let you know the actual yield when it is assembled and, Finally, used on the sky
Fabio
The rotating plateau on which the mirror is installed is interesting!
I don't mean much about empty autoclaves for the storage of alumination.
You can describe how the photographed one works?Unfortunately I don't know much about aluminizing cameras either. I have only had some experience with plasma treatment vacuums, much more …mixture.
In this room, in particular, there is a beautiful one turbomolecular pump (the “fan” on the right of the image) from 2000 liters/hour on magnetic bearings (so there is no oil to evaporate - although oils exist “from empty” the fewer there are around the better). With this pump you can create a vacuum in approximately 2 hour (and here the vacuum is 1E-7 bar!).I know a little vacuum technology because I took charge of the construction of large electrical transformers in medium voltage, and transformers for high frequency induction of steel tubes welding generators. All vacuum impregnated in epoxy resins of the first and the second silicone to eliminate and blowholes in the insulating castings.
But the required vacuum was not as driven, and it was already obtainable with common to oil ring vacuum pumps.
I also know the molecular pumps that operate at “Rain”, molecular exploiting the removal by shock of the few molecules remained by the vacuum in oil, necessary to achieve very vacuums.
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