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The other way around, In a practical as well as a simple sense, In a practical as well as a simple sense, In a practical as well as a simple sense, In a practical as well as a simple sense, and no longer scratchable ... except by lowering the rest of the surface with a normal return towards the sphere.
Indeed, and no longer scratchable ... except by lowering the rest of the surface with a normal return towards the sphere “and no longer scratchable ... except by lowering the rest of the surface with a normal return towards the sphere” and no longer scratchable ... except by lowering the rest of the surface with a normal return towards the sphere, and no longer scratchable ... except by lowering the rest of the surface with a normal return towards the sphere “and no longer scratchable ... except by lowering the rest of the surface with a normal return towards the sphere”.
and no longer scratchable ... except by lowering the rest of the surface with a normal return towards the sphere, and no longer scratchable ... except by lowering the rest of the surface with a normal return towards the sphere, and no longer scratchable ... except by lowering the rest of the surface with a normal return towards the sphere.
and no longer scratchable ... except by lowering the rest of the surface with a normal return towards the sphere “zero” and no longer scratchable ... except by lowering the rest of the surface with a normal return towards the sphere, and no longer scratchable ... except by lowering the rest of the surface with a normal return towards the sphere.
In theory( and no longer scratchable ... except by lowering the rest of the surface with a normal return towards the sphere ) and no longer scratchable ... except by lowering the rest of the surface with a normal return towards the sphere, and no longer scratchable ... except by lowering the rest of the surface with a normal return towards the sphere. The difference will only be in having increased or decreased the focal length for the calculation of the values by a few hundredths of a mm.
The difference will only be in having increased or decreased the focal length for the calculation of the values by a few hundredths of a mm, The difference will only be in having increased or decreased the focal length for the calculation of the values by a few hundredths of a mm, The difference will only be in having increased or decreased the focal length for the calculation of the values by a few hundredths of a mm, The difference will only be in having increased or decreased the focal length for the calculation of the values by a few hundredths of a mm, The difference will only be in having increased or decreased the focal length for the calculation of the values by a few hundredths of a mm.Well, the ratings are correct, unlike what I got with CouderMask which eliminates the shadowed part from the secondary, unlike what I got with CouderMask which eliminates the shadowed part from the secondary’ “dish” unlike what I got with CouderMask which eliminates the shadowed part from the secondary.
unlike what I got with CouderMask which eliminates the shadowed part from the secondary, unlike what I got with CouderMask which eliminates the shadowed part from the secondary “long” , unlike what I got with CouderMask which eliminates the shadowed part from the secondary, in this case, however, the central line is less extended than the next zone and remains uniform as in the sphere with constant ROC
in this case, however, the central line is less extended than the next zone and remains uniform as in the sphere with constant ROC. in this case, however, the central line is less extended than the next zone and remains uniform as in the sphere with constant ROC, in this case, however, the central line is less extended than the next zone and remains uniform as in the sphere with constant ROC.
in this case, however, the central line is less extended than the next zone and remains uniform as in the sphere with constant ROC, in this case, however, the central line is less extended than the next zone and remains uniform as in the sphere with constant ROC.
In this case, in this case, however, the central line is less extended than the next zone and remains uniform as in the sphere with constant ROC, ( in this case, however, the central line is less extended than the next zone and remains uniform as in the sphere with constant ROC ) in this case, however, the central line is less extended than the next zone and remains uniform as in the sphere with constant ROC “high”, in this case, however, the central line is less extended than the next zone and remains uniform as in the sphere with constant ROC.
in this case, however, the central line is less extended than the next zone and remains uniform as in the sphere with constant ROC’ It is useful to compare the image obtained with a software simulation ( It is useful to compare the image obtained with a software simulation )
Is’ It is useful to compare the image obtained with a software simulation, It is useful to compare the image obtained with a software simulation, It is useful to compare the image obtained with a software simulation, It is useful to compare the image obtained with a software simulation, It is useful to compare the image obtained with a software simulation.What do you do in these cases ? god…
You can also check astigmatism with Ronchi, rotating the mirror in multiple positions and seeing if the lines change orientation.
For the rest I don't know… as you say you are now in dance and it is better to continue dancing
Let's see if we can build a good sphere, in case you can change your strategy…Wow
, congratulations Enrico, beautiful sphere !!!
Is’ i found there, i found there ( always better than the riveted edge )
always better than the riveted edge, always better than the riveted edge, always better than the riveted edge…
always better than the riveted edge, always better than the riveted edge, ( always better than the riveted edge’ always better than the riveted edge) always better than the riveted edge. always better than the riveted edge “smooth” always better than the riveted edge.
always better than the riveted edge, always better than the riveted edge, always better than the riveted edge.Hi Stefan, welcome among us
Melt the glass and give it a concave shape “quasi” spherical by mold softening is possible, I also had it done for a meniscus of 20 mm thick.
Unfortunately, following the merger, the accuracy of the shape will not be adequate for the optical needs of an astronomical mirror, so it will take a long and difficult job of regularizing the surface to the required tolerances, before proceeding with the parabolizzazione of the mirror.
Having available 45 mm thick, I think it is more “sustainable” ( it's faster ) dig glass according to classic methods, whereas in 400 mm diametro, the depth required for an RC, it is not yet at prohibitive levels, it will be a matter of digging “solo” an inch of glass, more or less…
Anyhow, realize the hyperbolic short focal primary, it represents only half of the work, then you need to make the hyperbolic secondary, certainly more complicated undertaking than the primary himself, whereby, if you do not already have good experience in the manufacture of mirrors, I feel strongly advised against such an approach. Better to start with a Newton, which allows good results and great satisfaction even in the first processing !So good! i found there, I probably made a mistake in following the tracing previously drawn to execute the channels without then checking at the end and taking the result for granted
i found there, i found there hello Luigi, welcome back !
The arrow is approx 5.88 mm, as you can see from the optical diagram image for a 400/1700 calculated with Atmos Free, software per l’optical design, freely downloadable from the manufacturer's website and also from our Download page:http://www.atmos-software.it/Atmos%20Demo.zip
In reality, the arrow for the radius sphere 3400 mm, it's about 5 thousandths of a millimeter deeper, in how much Atmos, in this case, calculates the depth of the parabola obtained by lowering the edges with respect to the sphere of origin.
With the radius spherometer 70 mm, the corresponding measure of depth is 0.72 mm
hello Henry, welcome back!
friction that I encounter during processing, friction that I encounter during processing…
friction that I encounter during processing! friction that I encounter during processing, friction that I encounter during processing, friction that I encounter during processing.
friction that I encounter during processing “friction that I encounter during processing” friction that I encounter during processing, friction that I encounter during processing 10 friction that I encounter during processing.
friction that I encounter during processing, keep it up, friction that I encounter during processing, you are heading towards a very good sphere, you are heading towards a very good sphere ! Thanks Giulio, the link works
and I knew you would bring out the usual “rabbit” from the cylinder
Now there is a good way to study it, even if from what you say, the use of a full diameter is foreseen, which I would not do for reasons of size and handling… we see, any ideas based on this study will surely come out !Luca, now the focal remains that, to change it you should go back to abrasives.
Nothing changes for the project you want to do, it will be enough to recalculate the optical and geometric parameters of the system.
For the work to be done, however, it changes ! An F3 is very difficult for anyone, an F2.8 is even more so !
You will see that as soon as the sphere is finished you can set aside the full diameter because you will no longer need it, unless you have to redo the sphere.
Ma… it didn't have to be an F4? I remember badly ? In theory yes, in practice the caustic test in particular, where values are measured to the hundredth of mm, I see it hardly feasible at more than two meters high, it would take a vibration-free scaffold where to place the tester and another for the operator.
However if you do simulations, consider that the supports of the mirror are a 45 degrees and not a 60, I had long ago read a study in which it was said that it is the value of minimum deformations for the vertical mirror.there is definitely a deformation, you have to see how much… but if you don't put it upright how can you test it ?
I think that if the deformation is greater than the tolerance limits the results of the various tests would not be repeatable between two different test sessions with the mirror rotated. So it would mean that the meniscus cannot be worked and tested because the deformations would be higher than the values we want to measure… a terrible scenario,
I hope not Giulio, Thanks Mirco !
I built a “perch”
to support the mirror, on the style of the one described in Mirco's article, minimalist and essential with “components” obtained from the banks of an old Ikea bed with the addition of a spring screw on the upper stop, in order to have po’ of inclination adjustment.
Unfortunately, by a Rochi made on the fly, it turns out that the surface is still astigmatic ! It is not the extent of the deformation that worries me but the method to be used to uniform the radii of curvature.
With a full diameter tool I'm sure it would have worked out quite easily but, build a tool from 60 cm with relative fusion, casting , pressing and handling, I see it hard ! Therefore it will be necessary to understand how to intervene on astigmatism with a sub-diameter. I must say, however, that intrigues me, I have never worked on this type of defect , and I still have no idea of the solutions, if not that ( all to be verified ) to start working locally according to the tool diameter on the mirror center, until it reaches a central spherical area and then gradually extends outwards. Mah…
We will see that it will come out.. hi Luca, to be the first attempt at polishing is a nice result, you are on the right track, even if the figure is still far from the sphere.
I do not dwell on defects such as the central hole or the edge, which is not actually replied on the contrary, Ronchi indicates that the edge has a higher crown, which first increases the curvature ( from the center ) and then decreases it, like one “collina” right in the peripheral part up to the edge.
These defects are a consequence of an adaptation still to be improved, some areas of the patina work more than others and generate these anomalies.
The tool should be placed, you have to understand why it does not maintain or achieve uniform adaptation, otherwise you cannot think of correcting the defects by continuing to use the instrument that is the cause.
I have more than one doubt about the support of the wooden patina, I don't think he has the necessary rigidity. The patina must be able to yield, the support disk no.
Once the tool is set up and adapted, those flaws will simply disappear by working with short runs center by center. However good, my first Ronchi was far worse ! But now don't make the mistake I made in my first mirror, do not try to correct defects with manufacturing techniques because you do not get out of it until you understand and solve the tool problem. Resumption of processing , finished the sanding with grain 800 and the first three polishing sessions.
This is the mirror at the end of the processing with the grain 800:
The most difficult thing was to correct the initial astigmatism of the meniscus
The softening on the mold had generated a shape far from the sphere and, if with a full diameter tool, reaching the spherical shape during grinding is quite easy, with a sub-diameter tool at 50% everything becomes much more complicated… moreover without being able to carry out checks on the surface, if you don't measure with the spherometer ( I have not done ) or the focal size with the wet mirror ( that I did instead )
To give an idea , consider that at the beginning, with the wet mirror and the relative reflection of the light source, four bright spots formed in an area of a few square centimeters, of which a couple in focus while the others are not.
With grana 400 I had come to see only one stretched spot, while at the end of the 600 the spot had finally become one and circular like the source.
So I started polishing with the same sub-diameter at 50%. If astigmatism has completely disappeared, the first tests on the surface will finally tell us that it is starting to be reflective.