C7 = (Integral of product of h*Z7 over the surface)/(Integral of Z7*Z7 over the surface) Where Z7 is the Zernike polynomial and C7 its amplitude The Integral of Z7*Z7 over the surface = 1/8. The

On Mon, May 10, 2021 at 04:19 PM, <jeanpierre_chiappini@...> wrote: This factor is [r * (- 2 + 3 * r²) * sin (a)] How to use the (h) at each point to calculate the coma sine term (Z7) ?Much like

Good morning all, If we know the wave front (W) or in other words we know the height of the deformation (h) at each point expressed in wave value, how are the zernike terms calculated? For example how

Paul, thanks for your letter. About Gregorian telescopes on the mid. of 18 century - they could be left all spherical and be diffraction limited. Attached please find a design sample of 2.25"

Thanks for that!! Lost me at "Thin lens" Kind regards, John From: Interferometry@groups.io <Interferometry@groups.io> on behalf of Interferometry@groups.io Notification <noreply@groups.io> Sent: 08

The wiki page Diverger lens Residual Spherical aberrationhas been updatedby Bruce Griffiths <bruce.griffiths@...>. Compare Revisions

Yuri, Remember that James Short was making Gregorian Telescopes of a crude nature before there was a full understanding of the properties of the Gregorian Configuration. If he was matching secondary

Dale and All, I have to put this project on hold. Just need to study more about testing of a non-spherical mirrors. Yuri

Another way to find focus point is almost identical to how you do it with Foucault tester: First remove all tilt - in other words try to get a "bulls eye" pattern visible. Then push gently on the

Dale, I will play with a defocus on the weekend. Moving 1mm from the ROC point will make too many fringes, I will try a smaller amount (up to 10 micron level). So far I have checked the result by

George, thanks for videos, I watch the first one at lunch and got some info I missed, thanks a lot! As per the Bath, I am not familiar with it, doing all test with a very compact TG for APOs testing.

Yuri, When using a Bath interferometer how far you set it from the ROC of the Mirror determines the defocus value. I assume that will be the same for the interferometer you are using. So move the

Wait - I just realized I'm replying to Yuri. I think Yuri knows just as much about Bath Interferometers as I do and probably doesn't need to watch my videos. Hmm. So why disable the null?

The defocus value is calculated from your igram. If you have the bath setup exactly at focus - the nominal distance form the mirror - you will get a defocus of 0 waves. You can tell when the Bath is

- thanks a lot, Dale. Your results are quite different (one magnitude order) than mine... It is almost a diffraction limited mirror (!). I hope it is close to reality. I have a few more mirrors of the

My bugs turned out to be operator errors by me. Here is my analysis using a blue circle center filter value of 9. Not too bad of a mirror for it's time. Rolled outer edge and a raised ring

Yuri, Thank you for the igram. I'm working on it. I get what I think is a reasonable analysis with a blue circle of 8 to 9. At that point I get a strehl of about .7 using a gaussian filter of 5%

Dale and All, I am trying to test antique mirrors made in the 17-18 Century. They are mostly the metal primary mirrors from Gregorian type telescopes. Diameters are in range from 1" to 4", all have a

Dale, thanks a lot for this update! It is great! I have had no crash so far. Franz

Yes, mine looks the same. The resolution of my display is lower: 1680x1050 On Monday, May 3, 2021, 8:30:01 PM GMT+3, George Roberts (Boston)