A few forums ago I was asked about International Standards that are used for testing of optics (or any other objects or such)
I found Adam's video to be helpful in explaining why these are important. When ATMer's or any other tester goes about measuring their optic(s) There has to be an agreement between the test taken at lab and one done at home. The conditions and the tools (ie, interferometer, digital rail, software, etc... ) should be equal to or better than the conditions to which it was done. That is why ISO and ANSI and such standards are used to make sure there is an agreement between the two. I am not saying that such tests by ATMers or others are not valid and should at least get near to or read about the same. But you as the customer, supplier or user should understand the conditions they were tested in. That is why when I mention the battle of the ZYGOs (other such interferometers) is and can be an issue. The conditions should result with the same value(s).
If you are new to telescope making or need to understand the values to which your measuring your telescope mirror, secondary, lens, or any other optic. Adam gives a fair lesson on how precision measurements are made and why there are many factors to consider when such measurements are taken. The video is a simple explanation on why, how and use standards, in his case Gage Blocks, to measure in microns. For telescope makers, you are making surfaces to a fraction of that. If you are trying to learn machining of parts for you scope, it is helpful to understand how using gage blocks are helpful to gage tight precision while machining. That is why I having been in QA and understand the study of measure it's important to learn why sometimes the values maybe different and hard to repeat.
I hope this bit mentoring is helpful to you.
It's worth watching and fun to watch. There are times I was a bit nervous about the blocks falling on the floor. But in the
end he is aware he is a bull in the glass shop. Enjoy. If you are a fan of Adam, you will understand.
From the comment section:
"Any measurement without the knowledge of uncertainty is meaningless" - Walter Lewin
"All measurement is a compromise of circumstance"
Edited by Oregon-raybender, 05 January 2022 - 05:43 PM.