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Sample tower

The 2-BM Fixture that materializes the cross-facility SampleTower Assembly: the sample positioning stack, binding the installed stages, presenting the Positioner Role, with the kinematic order carried as a containment chain.

The sample tower sits in the 2-BM experiment hutch (Enclosure 2-BM-B). It is the operator-facing positioning system: a stack of motion stages, floor to sample, that places and rotates the specimen in the beam. Standard tomography, laminography, and mosaic / large-sample scans all run on this one tower; they differ in the scan recipe, not in the installed hardware. This page explains how CORA models it.

The model in one picture

The kinematic stack, floor to sample (containment, Asset.parent_id):

2-BM  (Unit, Asset)
└── SampleTable  (Device, Family Table; base, floor-referenced)
    └── Hexapod  (Device, Family Hexapod; coarse 6-DoF pose)
        └── LaminographyPitch  (Device, Family TiltStage; Kohzu goniometer)
            └── Rotary  (Device, Family RotaryStage; theta air-bearing)
                └── SampleTop_X  (Device, Family LinearStage; co-rotates with theta)
                    └── SampleTop_Z  (Device, Family LinearStage; co-rotates with theta)

The composition the Fixture materializes (Assembly to Fixture):

Fixture: sample_tower_at_2bm
└── materializes Assembly = SampleTower  (presents_as the Positioner Role)
    ├── slot table         -> SampleTable
    ├── slot coarse_pose   -> Hexapod
    ├── slot tilt          -> LaminographyPitch
    ├── slot rotation      -> Rotary
    └── slot sample_top    (OneOrMore)  -> SampleTop_X | SampleTop_Z

SampleTower is the name of the Assembly (the blueprint). The conceptual tower-the-thing IS the Assembly plus its Fixture; there is no single physical chassis Asset (unlike the Microscope's Housing), because the tower is a kinematic stack where each stage is bolted to the one below.

Two axes: composition and containment

Like the Microscope, the tower uses both of CORA's structural axes, and they answer different questions.

  • Composition (Assembly to Fixture, flat) answers what logical cluster presents here for binding. The SampleTower Assembly composes five leaf slots; the Fixture binds them to six concrete Assets (the sample_top OneOrMore slot carries two). The Assembly presents_as the Positioner Role, so a Method can require a sample positioner as one typed unit.
  • Containment (Asset.parent_id, a recursive tree) answers what physical thing holds what. Here it is a literal-deep chain: SampleTable parents the Hexapod, which parents LaminographyPitch, then Rotary, then SampleTop_X, then SampleTop_Z. Each stage's position depends on the one below, which is the physical truth and is why the chain is deep rather than the Microscope's shallow housing-parents-all.

The two axes are orthogonal: the same Assets sit on both at once.

The experiment-vs-loadout boundary

The load-bearing rule: a different scan over the same installed stack is a Recipe Method / Plan; a different installed stack (a stage added, removed, or physically exchanged) is a different Fixture.

  • Tomography, laminography, and mosaic are all Method/Plan over this one Fixture. Laminography is not a separate instrument and not a second loadout: the Kohzu LaminographyPitch goniometer and its fixed wedge are permanently installed, and tomo vs lamino is a tilt setpoint on that stage (a Plan parameter), not a hardware insert or remove. Mosaic / large-sample tiling steps the SampleTop and table translations between sub-scans on the same stack.
  • A second Fixture is reserved for a real hardware exchange. The 2-BM rotary kit (ABRS-250MP-M-AS installed, plus ABRS-150MP-M-AS and the ABS2000-1000AS-RU spindle, per the staff sample motor stack page, item_050) is interchangeable in principle, but the b-station stack runs the single installed ABRS-250MP today, so the swap is a future trigger, not a live loadout variant.

Families

The tower introduces one new Family and reuses the rest.

  • TiltStage (new): the Kohzu goniometer that tilts the rotation axis. A tilt is a rotational, limited-range stage, so it is not a LinearStage; and it is not a RotaryStage, because that Family's affordances include Following / Marking for the theta position-synchronised-output fly-scan, which a tilt does not do. TiltStage affords Rotatable, Homeable, Limitable.
  • Table (the base): the bare role-noun for the sample optical table, following the OpticalHousing to Housing precedent (the qualifier names the contents, not the chassis kind). The Asset instance is SampleTable.
  • Hexapod, RotaryStage, LinearStage are reused unchanged.

Exercised model

The end-to-end model lives in apps/api/tests/integration/scenarios/test_2bm_sample_tower_setup.py: the Unit install, the five Families, the six stack Assets in the deep parent_id chain, the per-constituent Mount/install, the SampleTower Assembly presenting as the Positioner Role, the one Fixture binding the five-slot stack, the attaches, and a positioning Method/Practice/Plan that requires the tower as a unit (needed_assembly_ids). The scenario also asserts the experiment-vs-loadout boundary (the Fixture carries no scan-strategy override).