Techniques¶
What CORA would run at CDI: coherent-imaging techniques, each a Catalog Method. CDI follows the deferral the coherent and scanning beamlines set, after Diamond i13-1, which opened the pending ptychography Method, and APS 8-ID, CHX, and HXN.
CDI's techniques are coherent diffractive imaging: focus a coherent beam, record the far-field diffraction pattern, and recover the real-space image offline by phase retrieval. These Methods are new to CORA's imaging- and spectroscopy-heritage catalog, so the Methods below render unlinked and are carried pending until the owner-scope decision (TECH-1) brings them into the catalog.
| Technique | Catalog method | Notes |
|---|---|---|
| Ptychography | ptychography |
a scan of overlapping coherent-diffraction frames across the sample; reuses the pending ptychography Method Diamond i13-1 opened; the reconstruction is a ComputePort leg, not a beamline Method (the HXN framing) |
| Forward CDI | coherent_diffraction_imaging |
a single far-field coherent-diffraction frame on the Eiger2 / Merlin from an isolated object; the single-shot variant of the same deferred coherent-imaging cohort, not separately coined |
| Bragg CDI | coherent_diffraction_imaging |
a rocking series around a Bragg peak for strain imaging of a crystalline grain, with the goniometer setting the orientation; the same deferred coherent-imaging cohort |
| Alignment | alignment |
beam, KB, mirror, and slit tuning; reuses the existing Method |
All three imaging techniques need the KB nanofocus and sample stack and the coherent detectors; how the exposure is gated on the floor is the open timing question (TIMING-1).
Why the Methods stay deferred¶
Diamond i13-1 opened the coherent-imaging Method as the pending ptychography Method (the fleet's first coherent diffractive imaging), carried pending until a conduct-path earns it (TECH-1). CDI reinforces that Method at a second facility and adds the single-shot forward and Bragg CDI variants, which are not separately coined; the concrete acquisition recipes (frame counts, scan grids, rocking ranges, exposures) join as the deployment approaches the point where CORA drives the beamline. This is the same earn-the-abstraction discipline the deferred small_angle_scattering (8-ID, CHX) techniques follow. Because the full coherent-imaging Method scope is not in the catalog, CDI records no Practice in the NSLS-II Site, as CHX records none for its coherent-scattering Methods; the binding lands when the Method does.
The phase retrieval itself (the iterative reconstruction that turns the diffraction frames into a real-space image, and the ptychographic engine that solves for object and probe together) is ComputePort work, not a beamline Method. This is the imaging analogue of CHX's correlation analysis: the beamline takes the frames, CORA's compute leg turns them into the result.