CDI¶
Coherent diffraction imaging at NSLS-II, beamline 9-ID: a forward-CDI, ptychography, and Bragg-CDI beamline that focuses a coherent beam with a KB mirror pair and records the far-field diffraction pattern on photon-counting area detectors. This page describes how CORA would model and run CDI; the model is reverse-engineered from public configuration, not yet confirmed by CDI staff.
| Property | Value |
|---|---|
| Asset | CDI (root Asset, tier = Unit, parent_id = None) |
| Facility | NSLS-II (bound via facility_code = "nsls2", FacilityKind = Site) |
| Sector | Sector 9 (PV namespace XF:09ID*) |
| Institution | Brookhaven National Laboratory (context; not modeled as an Asset or Facility) |
| Status | Reverse-engineered from public config (design-phase scaffold) |
| Source | IVU18 in-vacuum undulator (SR:C09-ID:G1{IVU18:1}) |
How CORA would land on CDI
This is NSLS-II 9-ID. CORA also models APS 9-ID, a different beamline at a different facility; CDI lives at XF:09ID*. These pages describe how CORA would model, govern, and conduct CDI, joining the NSLS-II coherent siblings CHX and CSX and the ptychography-capable nanoprobe HXN. They are not a survey of the beamline's current software. The hardware facts (devices, EPICS PVs, axes) are read from public NSLS-II open source (the NSLS2/cdi-profile-collection profile collection and the NSLS2/cditools device library) and verified against them; vendor part numbers and physical positions are not in them, so they, and every read value, are carried confirm until CDI staff verify them (Open questions). This is a design-phase scaffold: the descriptor and these docs, with scenarios deferred.
The defining shape: coherent imaging¶
Coherent diffractive imaging arrived in the fleet with Diamond i13-1 (ptychography and CDI, a deliberately partial endstation), which opened the deferred coherent-imaging Method. CDI is the second coherent-diffractive-imaging deployment, the first at NSLS-II, and the first modelled as a full source-to-detector beamline: it focuses a coherent beam to a small spot, records the far-field diffraction pattern on a photon-counting area detector, and recovers the real-space image offline by phase retrieval. The fleet has met coherence in other acts too: APS 8-ID and CHX record correlation time series (XPCS), CSX records coherent soft X-ray scattering, and HXN runs ptychography as one of several scanning-probe modes.
The value to CORA is reinforcement, not new vocabulary. The coherent area detector that records the diffraction pattern is the same Camera shape CHX and HXN already carry; the KB nanofocus that forms the coherent spot is the same Mirror shape FMX and SRX carry; the offline reconstruction is a ComputePort leg, the imaging analogue of CHX's correlation analysis, not a beamline Method. CDI introduces no new catalog Family, and its techniques reinforce the deferred coherent-imaging Method i13-1 opened (the pending ptychography Method) without coining anything new.
The three imaging techniques differ only in how the frames are taken: a single far-field frame (forward CDI), a scan of overlapping frames across the sample (ptychography), or a rocking series around a Bragg peak (Bragg CDI). All three share the KB nanofocus, the goniometer, and the coherent detectors.
The beamline¶
Along the beam, in order:
- Source: the IVU18 in-vacuum undulator and the first-optics hutch (
9-ID-A), rendered as the generated source-stage device walk: the silicon double-crystal monochromator and the double-multilayer monochromator, the vertical and horizontal pre-mirrors, the white-beam and branch slits, the attenuator foils, the master energy, and the upstream beam diagnostics. - Sample: the KB nanofocusing mirror pair that forms the coherent spot, the beam-conditioning unit that trims it just before the sample, the sample goniometer, the endstation positioning towers, and the endstation diagnostic cameras.
- Detector: the Eiger2 and Merlin photon-counting area detectors that record the far-field coherent-diffraction pattern.
Cutting across all three:
- Controls: the motion controllers and the timing seam. Unlike the other NSLS-II coherent beamlines, the CDI profile collection exposes no hardware trigger box, which is the headline controls question.
The cross-cutting reference view is the Inventory.
Techniques¶
Techniques: the coherent-imaging techniques CDI runs (forward CDI, ptychography, Bragg CDI), each a Catalog Method, and why their Methods stay deferred (the 8-ID / CHX / HXN owner-scope cohort).
Governance¶
Governance: who may act at CDI and the trust shape CORA applies; CORA brings its own per-Actor authority.
Model¶
Model: the developer's by-kind index into where each CORA aggregate's CDI content lives.