daughter's 6" f:10 mirror
That gene thing might be right Art. I understand that some talents skip a generation, repeating every second generation. J
I just uploaded another photo, Ripple.jpg to the “Jerry” album.
It took 4 figuring sessions to go from “Ripple” to the finished mirror.
The first session was to remove the ripple and added a little parabolizing at the end of the session. The ripple was almost gone but correction was about 200%. J With this mirror that is about 1/7 wave PV. Well… It still needed some smoothing anyway.
After the second figuring session the PV error was 1/16 wave smooth over-correction (hyperbola), but the doughnut was ugly. With the 6” f:10 small errors can destroy the beauty of the doughnut.
After the third figuring session (MOT “oblate maker’s stroke” J) the PV error increased. The correction reduced in the central zones and increased at the outer zones.
The fourth figuring session was TOT “oblate maker’s stroke” (1/3D narrow W). That brought the outer zone correction down to 100%. The correction slowly reduces toward the center amounting to the 1/25 PV error.
Should have had her do just a little less of the MOT oblate maker. It would have been 1/100 wave! J
I need to make a device to hold my camera on the tester. These are hand held images. I had to take many images to get some without much movement. It forced me to make shorter than ideal exposures and there is much noise in the image. It looks better with the eyeball.
In the image of the finished mirror the brighter spot in the diffraction ring at about 8 o’clock position is an internal reflection of sunlight from a window. At the bottom of the mirror about 30º around left and right from bottom center are spots at the edge, dark on the left and bright on the right. This is surface deformation from the mirror support points.