Three refinements found while testing find_rotation_center() against the
simulated LamNI:
- Drop the trailing tomo_rotate(0) at the end of find_rotation_center():
both the isolated path (explicit rotate-back before applying the
correction) and the extended path (verification sweep ends at 0) already
leave lsamrot at 0 by then, so it was a pure duplicate move.
- Simplify _live_sweep() to rotate directly to each waypoint instead of
stepping through artificial step_deg-sized sub-moves with settle pauses
in between -- a single tomo_rotate() already produces continuous physical
rotation, so the stepping added nothing but jerkier motion and extra
queue overhead.
- Add _ensure_at_configured_center(), called at the start of
find_rotation_center() before lfzp_in(). lamni_move_to_scan_center's
interferometer-drift safety check (LamNIFermatScan.py) assumes lsamx/
lsamy start near their configured center and silently skips the entire
corrective move if that drift exceeds 150um -- exactly the situation
find_rotation_center() is meant to handle, since its purpose is
recalibrating a potentially-stale center. Confirmed this was a real gap:
a run where the stage hadn't started at its configured center produced a
correct absolute target (verified via the interferometer reading) but a
confusingly small apparent motor delta.
Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
