Making a monolithic telescope Part 3: Figuring & Testing

Use the following links if you want to skip to the next chapter of the video: 00:00 General intro 01:54 Required level of precision 07:12 Measuring surface shapes with interferometry 10:46 Fringe evaluation with DFTfringe 12:12 Optical Pitch polishing 17:19 Making molds using 3D printing 18:18 Results with variable surface tools 21:06 Primary mirror 22:20 Point Diffraction Interferometry (PDI) 26:48 Visual performance 29:58 NO MORE NAPS (featuring Dr. Fullersheit) Links mentioned in the video: Website with the best and most detailed information on telescope optics: https://www.telescope-optics.net/. This is the direct link to the page about the different criteria and how they relate to aberrations: https://www.telescope-optics.net/effe... The 3D-printer used was manufactured by 3Bfab. More information on their products can be found on their website: https://3bfab.com/ (not sponsored content - they did neither ask nor pay me to show their product) DFTfringe software is programmed by Dale Eason. This is the link to his YouTube channel:    / @daleeason9687   The software can be downloaded from: https://github.com/githubdoe/DFTFring... This is the link to the interferometry group on DFTfringe that Dale runs: https://groups.io/g/Interferometry The Point Diffraction Interferometer can be purchased for about 50 Euros from Michael Koch at http://www.astro-electronic.de/ (not sponsored content) Other videos in this series: Part 0: Tiny telescope concept video (featuring Rik):    • Why is this Space Telescope so Tiny?   Part 1: Optical Design and Aspherics;    • Making a Monolithic Telescope Part 1: Opti...   Part 2: Machining Glass;    • Making a Monolithic Telescope Part 2: Mach...   Special thanks to Dr. Liam Fullersheit for his guest appearance. (;-).