How are Coronagraphs Designed?

[Jashcraf]

All coronagraph designs are some approach to the problem of "maximize planet light, minimize starlight" but not all algorithms are created equal. This is where I will be collecting information about the different approaches.

[Jashcraf]

Jewel's Auxiliary Field Optimization

Embed the original optimization problem for either phase or amplitude in various planes of the coronagraph into a problem containing additional degrees of freedom.

This technique operates on a segmented aperture with spiders, so 2 DMs are used and Fresnel propagation is required. The coronagraph under test is an apodized pupil vortex coronagraph, and they examined the results for SCDA apertures.

Section 3 reviews the Auxiliary field algorithm

"Non-convex" problem - which i think just means that there are multiple local minima. They appear to optimize the SPM with DM shapes.

[Jashcraf]

Por's APLC Optimization using Pupil Symmetries

paper link

Main considerations are

• high sampling of mask arrays
• operate in broadband light
• insensitive to small misalignments of the Lyot Stop
• passive suppression of low-order aberrations

To reduce the memory required to compute these optimizations, they 1) make the masks mirror symmetric 2) progressively refine the arrays by beginning with low-sampled arrays and moving to higher resolutions at later iterations.