|
Stephen, to finish answering your question about a numerical value that quantifies the ultimate quality of your optics, this can be approximated by visual techniques, but it is only possible following a lot of experience and knowing how to conduct bench tests, the various tests required and how to interpret the information these tests provide.
An example of this is the testing carried out by a Russian optical lab. They have the necessary equipment to thoroughly investigate a set of optics that access the different values and provide the ultimate quality value that is provided in a series of values, such as Strehl, RMS, P-V, and a few others. These all tell slightly different things about the optics, though not contradictory. Of these different values, the Strehl rating is the one that's most significant as it is the overall quality rating, as a ratio where 1.0 is "perfection", exceptional quality would be something like 0.974, mediocre quality is 0.767.
I'll chase up a link to this Russian lab.
Alex.
|