Higher order CTF expansions

[Miro-Astore]

For high resolution data, higher order CTF correction such as "Beam Tilt" matter greatly.

According to Kirkland chapter 6, the full expansion of the CTF is simple zernike polynomials.

https://en.wikipedia.org/wiki/Zernike_polynomials

We will create a "ZernikeCTFBasis" object which can be called by other forms of ContrastTransferTheory.

[geoffwoollard]

Perhaps this implementation of higher order CTF would be helpful for testing against: https://github.com/abTEM/abTEM/blob/main/abtem/transfer.py

[mjo22]

Sounds good. We should think about what API we want for this.

Two requirements that come to mind on the cryoJAX side are:

• Parameters must be implement as pytree leaves. In this case, this is coefficients in the expansion such as for aberration.
• __init__ and other class constructors must work with JAX transformations, such as vmap