I have been working on this mirror since some time now. The data of the mirror are as follows:
150 mm (6") diameter plate glass, 20 mm thickness, water jet cut, both sides were flat and there was no internal stress in the beginning.
Rough grinding was done with granite tool, 150 mm (6") diameter, 20 mm thickness water jet cut. Both sides were flat, parallel, polished.
After rough grinding was done, the domed part of the tool was used to pour the pitch over it and formed by the mirror.
Optical tests are done with a 5.23 lines per mm (133 lpi) Ronchi Grating. I have a moving light source that moves together with Ronchi Grating
My aim was to have a 200 cm (78.7") ROC, but I have now 194 cm (76.4"), it somehow got shorter in the way a little.
I worked recently in 27 degrees Celsius (81 degrees Fahrenheit) constant room temperature.
Cerium Oxide is my polishing compound.
You can find my recent progress in the rar file of the following link. It is about 45 Mb in size, 73 files. Ronchi images and my tool.
The order of the files show the progress of the work too.
I take my pictures starting by farthest and going in the direction of the mirror. There may be some cases when I go a little back just a few shots.
My lap needs to be poured again, because the pitch is 3.6 mm in thickness on the sides and 4.2 mm thickness near the middle of the lap. But I have also worked with this pitch when it was 8mm thick on the sides.
I cold press my lap with mirror and some weight, using a window screen in between for micro channels.
I reached 44 total hours of polishing now, using different methods to get rid of the TDE that has developed at the end of 9 hours of polishing. That means I could not get rid of my TDE since 35 hours of polishing with CeO.
I have tried the fast methods in the videos of Pinbout too, but could not get better. I have also tried Accented Pressure Technique #5 from the page 21 of "Homebuild Reflector Telescopes" by Sam Brown, TOT but did not get rid of the TDE.
My questions are:
1-How bad is my mirror? Could someone please evaluate it?
2-How can I get rid of the TDE?
2-There is also a hill or valley (?) in the right hand side of my mirror, how can I get rid of it, how bad is it?