Hello All,
I am rather new at this so any help would be great.
I have always wanted to make a mirror. So dicided on my first attempt to make a 6" f5.6 mirror. All has gone well through the grinding and have done about 6 hours of polishing with a resin lap made from plate glass disk glued to plywood base with no scratches etc and the surface looks quiet invisible. I built a foucault tester which is a bit on the wobbly side (needs some more modifications) with a knife edge and a ronchi grating of 83 lines per inch. Slit about .003" inch gap.
I have posted a picture of what the surface looks like with both tests just inside and outdise ROC and was wondering if I can go on and try to parabolize or are my errors to large and shall I try to get to a better sphere first? Seems that the centre is flat or a hill?. Knife edge shadow appears in less than .1" more closer to .05". I still have problems reading these shadows but learning quick!!
Also what stroke would be recommended to fix it.
All help very appreciated...
Gary