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per “warm up”before the project 300 or 250 newton-cassengrain,I started thinking…
I started construction of a newton “planetary” da 15cm e f|8 about Focal.
You can affect I could share this little project, the objective parabolic
it's nice and ready,it is not something commercial,but is the result of tasks
in class made decades ago when I attended the Optical Institute,(although life has led me then to do anything else)the greater part has been performed
Prof. time,when I found myself in a drawer, I started the idea.
the objective has a diameter of 14,5cmm and a focal length of 1285 22mm thickness.
my philosophy is to saponara 100 x 100. to adapt objects created by other
and adapt,so nothing but each project ever “open”
..See you soonOf course it may concern ! I eagerly await to see how you intend to proceed and what ideas come out. Besides a parabolic F8 it should have excellent optical performance with a coma unnoticeable !
It might also be a good opportunity to get the knack of the Ronchi tests and foucault ( in view of the Newton-Cassegrain design ) with “the excuse” to verify at a distance of time the quality of this mirror.
This is the goal,I'm getting ready to paint the cell.
I would be curious indeed I need you to build a device for optical testing,I've got a network of Ronchi is etched ,Now I must clarify I .
give me some suggestions on how to build for the Foucault testHere it is all you need for the test set-up
today I had free 10minutes I started the construction of the primary cell ,
It was originally an aluminum pulley of an electric motor,I think that is enough classic
3 Wind and 120 degrees for support?
A cell with three points of support is very good for a mirror so small and so strong thickness.
If the web you will download the special software Gui Plop, which it is the well-known design program of the cells; (for example on: http://www.davidlewistoronto.com/plop/)
and then following the tutorial https://www.grattavetro.it/dimensionamento-della-cella-dello-specchio-primario-con-gui-plop/
Enter your information (including the diameter of the secondary mirror that I have "nose" estimated at 25mm), discover that the cell with three support points deform the peak ratio / downstream of your mirror of an infinitesimal value equal to 4,176 * 10 ^ -7 , (ie 0.000000417 * p / v) corresponding to a mean square error RMS of 9,522 * 10 ^ -7.
Since the text of the program guide (PloP user.pdf) It suggests that an error 4.2 * 10 ^ -6 corresponding to lambda / 128, It is considered a reasonably good limit, it follows that the error of the own cell of the three points of support is ( 4.2*10^-6 / 9.522*10^-7)= 4,41 times smaller than the minimum, and then over 4, 41 sometimes better than the limit “reasonably good”.
In conclusion, the cell of the three points for your mirror is great if they fall on a circle of radius 0,411971 the mirror radius, ie radius of 30,794mm, which it is also the only data of that cell constructive.
As for the meter Foucault and its use I will also recommend (if you have not already done) to read the text of Texereau downloadable whole or in sections from here: http://www.astrosurf.com/texereau/.
And if you download chapters, those of interest for the construction and use of the testers are in chapters 2 / A and 2 / B in which it describes in detail the construction of the primary mirror and the execution of its test and its corrections; and there is the description / tutorial of a tester (such as those I have built) and its use, to page 58 (ie astride the two parts into which it is divided by the chapter 2).but there is the downside I called but provide them only if you buy a glass blank
prized from them
The only affordable cost is the purchase of two discs up to 300mm in diameter, in normal glass (calcium-soda) 19mm thickness, at industrial glassworks, namely those that provide glasses for walkable floors and other uses in the building industry.
The last two records I paid them 100 totaling EUR, cut and crimped on 4 circumferential edges, leaving the remaining edge of rough cut.
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