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Hi everyone, in the short time I have available svuto I began to fix the shape of the tool surface, now finally approaches the ball, although there is still a little hole in the center and the slight edge retorted…
I also continued to mirror polishing, but here is the problem I can not solve.
To verify the shape of the mirror, sufficient to analyze the interference fringes that are created when they mate mirror and tool. Just begun the step of polishing (of entrabi) you saw 6-7 concentriche fringe, but then, continuing the work, the number of these fringes rose gradually up to twenty…This is a sign that the 2 curvature are moving further away, but I can not figure out if I should increase or decrease the curvature of the mirror to approximate the curvature (I tried to continue the polishing with mirror above, with mirror under etc., but the number of fringes seems to me more and increase…bah
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Ah, by pressing with the finger above the mirror you see the fringes move inwardly…any suggestions?If overlay tool and mirror without entering a lateral thickness, I think for the evaluation also accounts, and maybe more, check the spacing between fringes and fringe, that the number of fringes (that taken alone indicates a slope gradually increased).
For a sphere spacing grows exponentially, with a first circumference (Online round diffraction) rather large and gradually other circles closer and closer to the edge black. (as it would appear hypothetical contour lines of level on a spherical surface plan view).
For a conical instead, the first circumference has a smaller diameter than that of the ball, but then other concentric circles diffraction are few and almost equidistant. (also here the image of the contour lines on a cone would be concordant with this behavior).
To say that I rely not on experience, but on what I see in the picture “Table 1.1”, which is located on page 10 the following well-known book of Malacara interferometer newton, taking into consideration the left column of images of “Appearances of Newton’s fringes”, ie those that appear “without tilt”.
hello Giulio, thank you so much, I forgot to look in the book of Malacare, it's written all over…
It is true as you say that you have to look at the spacing between the fringes and actually seeing an exponentially smaller and smaller spacing, which means that the distance between the two surfaces increases more and more, but this happens is that the mirror has a greater curvature of’ tool, whether it has a lesser curvature of the tool (at the end of the relative distance it is always the same)…
The only way to understand which of the two situations is present is press on one of the two and see how they move the fringes…I think the answer is well explained on page 7 also with two beautiful drawings…
Now I do not have much time, but after I read it carefully and I understand the question well…Meanwhile, thanks again…
Ciao…
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