Hi Yuan,

A couple of questions. 

1. What is meant by “unconverted” Seidel coefficients?
2. Wouldn’t it make sense to include an option to plot the coefficients in waves?  See this post:

Thx,
Jeff

Hi Yuan,

Ok, thanks.  Yes, please submit a feature request and add my name.

With the current Seidel diagram, the user sees a comparison between the S coefficients, but as you show above, the S coefficients are related to their corresponding wavefront aberrations by various multiplicative factors (which, as far as I can tell, come from Seidel’s original work in ~1840) .  For example, S1 is eight times larger than W_040, while S2 is only two times larger than W_131.  These scale factors seem rather arbitrary.  So, it doesn’t really make a lot of sense to show S1 relative to S2 on a graph, when what is physically more meaningful is a direct comparison of W_040 (spherical in waves) to W_131 (coma in waves).

Regards,

Jeff

Great, thanks! 

By the way, here is what Welford says about the Seidel sum values after he goes through their derivation:

So, the numerical factors relating the S & W terms are not arbitrary, as they follow from the derivations, but the “customary” convention to simply drop these scale factors from the Seidel sums makes the S values somewhat less meaningful compared to the corresponding W values.

Regards,

Jeff