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Bravo Stefano!
The rectilinear rows and no longer curves show that the center is now improved in a very good ball. There is more to involve the outer ring, still important for just under a quarter of the diameter.
It just takes patience and time.
After the adaptation also made “to warm” in order to shorten the time to reach, Always keep an eye on that pitch in to work to reach its operating temperature. The good signs are that the cerium does the froth, pitch emanates conifer scent, and towards the end dried by contact pitch-glass arise acute wheezing.
If this happens it means that the pitch has the right hardness for your room temperature. If it were fischierebbe springs but would close the channels frequently; if it were the form together with the mirror would not change lasts more dangerous peche, but we mainly impart its.When it starts to be a little drier whistles makes them when I rotate the mirror on itself, when I make back and forth no. For the rest we. well rounded I keep my tool edges, a job 40 minutes and then at for 10 minutes, when microfaccettature begin to close and reopen the channels take the opportunity to also trim.
When the lines are perfectly straight at each focal length pass to parabolizzazione. But the figure of reference, taken by the Ronchi test software, It can be taken to any real focal distance? Then in reality you have to go try to get the same image moving at the right distance… Then once I obtained the correct image would move on to refine it in favor of abandoning the Ronchi Foucault, is the right way?This is the road that I've used.
The network of Ronchi is the fastest way to appreciate if the direction taken is the right.
Then I think when you get parable that produces interference patterns identical or very similar to those ottenure via software to various focal lengths, best switch to Foucault.
With the latter surely it is best appreciated the kindness of the parable or her mistakes.
I follow with great interest your job because even with my 300 mm for various reasons are firm for months now.
Stefano agree too that your way is the right one.
The focal distance varies the magnification of the grating, and perhaps this can be useful to look more closely at any raised edges or killed. However the Ronchi function is to assess the entire surface.
The sensitivity of the Ronchi instead depends on the number of lines per millimeter, because with Ronchi would escape each smallest defect dell'intrasse between two contiguous rows.The principle of Ronchi is also used in the body to pull up the stamps without having to repaint…
We assess the situation:
At this point it should fail again shortly to the ball. I am undecided whether to continue with Mot and spend 1 / 2D or Tot and spend 1 / 3D or shorter. The first should expand the processing center bringing it towards the edges, but my fear is that it is not sufficient to pave the raised edge. The second theoretically should work more on the outer edge, especially with past rather short. I almost feel Mot 1 / 2D, you who say?
Edit: You think, the edge is more raised than before or the optical effect is given by the fact that the lines are straight now to a larger diameter, and then the final curve is sharper?well Stefano, you're almost there ! the border is still a bit’ high while the peripheral part is almost correct. Always consider that there are two ways to achieve your goal:
1- break down the raised edge and bring it into line with the center
2- dig the center and bring it into line with the edge ( you will have a ball in this case more “closed” )in your first case ( AGAINST 1/2 ) get the solution 2 e, the other way around, the 1.
If I had to choose, seguiei you eat the Srada n.2.
Because the board is always a source of fast changes that it's okay not to activate, until it was just forced to the end of parabolizzazione.This also in the light of the fact that, to the attainment of the sphere, It is comfortable align it well with the tool diameter full, and those races 1/3 now they make you dig just because vex.
It would be better to get to the edge before utilizzaee pitch.
But there is never a serious impediment, e, how do you say, all roads (sooner or later) lead to Rome.
Now the thing that I have to be careful is to not fall into the trap of TDE!About this your fear, and with the intent to resize, I am attaching the Foucault test score sheet made of an initial spherical mirror as your, then mono radius, or on which are not detectable with the Foucault test variations of radius of curvature from the center to the edge, as it should be for a perfect sphere.
Placed in the gray boxes the work data concerning:
diameter mirror D19- focal length D20- sense “standard” from right to left of insertion of the blade into the optical path D21- Centers of 6 areas of the mask adopted Couder (Boxes E22 to j22)…
It has to write the same number of hypothetical draw (which can also be zero) in boxes from E27 to J27 to indicate that the mirror has the same radius in all 6 zones, and therefore it is spherical.
(If you click on the link, download the OpenO ffice .ODS spreadsheet, which also opens with excel)
https://www.grattavetro.it/wp-content/uploads/2017/09/TestDiFoucault-INIZIALE-per-6-zone.odsIf we now look at the blue background graph you'll see that the glass to remove the spherical surface to reach the theoretical parabola constructive reference date from Hm ^ 2 / R of the center of the Couder mask windows, it's tall 319.5 nm in zona 1 the center mirror (D45) e 329.3 in zone 6 (J45); while it is at zero in the area 3 to a 70% ray (in G22= 106 mm, which are precisely the 70% radius 150mm sopecchio)
This already says that the center and the edge are the high points of a ball away from the parable yet to make, and thus to bring down the board before starting parabolizzazione it takes a big commitment and a lot of bad luck.
That and the fact that it should be reassuring.
—————————————-Commenting on another chart that has the green background you can see double values Error, because the wave is damaged twice in the reflection (one in incidence and emergence in a).
The graph also presents a hump high at the center and the edge mirror (that is, the extreme left and right, but with values which in this case are set to zero those that touch the theoretical parabola in the upper reference (Red line), while the area that is to 70% radius is the one that has the maximum distance point to the value of -639 nm that touches the copy bottom of the green reference parable.
The ratio between the distance of “mistake” of the surface comprised between the two copies of the reference parabola, being 639 nm represents a labda (560/639=) 0.9 as shown in box H19.And this explains why to get a parable that is preecisa almenio lambda /4 You must halve the error on the best keeping glass or equal to lambda / 8
I would say the second option is functioning properly, if everything goes the right way tomorrow, with a 20 minutes of work should finally get a good ball and be able to start with parabolizzazione
More than anything I'm happy because I finally started to understand how to behave glasses with various types of processing, I began to realize pitch, the pressures etc.… the step of polishing is decidedly less intuitive of the previous phases but by beautiful satisfactions. I still miss the most critical phase but positive!I did not refresh the page, and your post I had escaped Giulio. Now I do a nice studied what you put! Thank you
More or less I should therefore be asking, it is essential to search for the absolute perfection of the sphere or this may already be an acceptable figure on which to work?Hi Stefano, with the premise that you're doing a great job, definitely at a higher level than that normally obtained with the first mirror, It might say that the flaws you see are small and do not create any problem for the ball, but create them for the parable, I'll explain:
For parabolizzare you will necessarily bring down the board and connect better sectors, at the moment, I am a bit’ “corrugated”, the lines are not completely straight.
And if the Ronchi seems a small thing, the foucault will reveal their exact measurement.
So you still need to come to terms, and it is certainly easier to reconcile a sphere that connect a parable !So in my opinion, better to do now more easily than they otherwise will have to be done then more difficult way.
More good is the ball starting the greater the chance of getting an excellent dish and, anyhow, parabolizzare for good, it is necessary that you understand how to fillet the sectors with continuity and how to intervene on the local defects, otherwise it is mostly luck ( which in any case it is always handy ! )
Thanks Massimo, I suspected it was the most suitable choice. I will work to improve the figure and connect areas in the hope that the quality of my network allow me to distinguish any small errors.
I will proceed further by working past the board with 1 / 2D and Mot, once you reached the goal, I will try to standardize the ball with the classic 1 / 3D and alternating Tot Mot. At work! I alternated and Tot Mot 1 / 3D to try to even out a little bit areas, after which I worked a little Mot 1 / 2D to break down the edge but it was not enough. Then I tried to work with Tot past court, 1/4D about but the “Turned up edge” I will not let go. Tips?
However, it is improved! Now it is a beautiful ball even though there are still those few mm to the edge of the field-
To break down the board with TOT races must be long, if you make them too short regenerate the raised edge.
You can try to do some’ racing W-TOT and then align with the usual 1 / 3D, so now that edge has past counted…
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