Sample¶
The TXM sample stage and the transmission-microscopy optics around it. All bind to the XF:18IDB-OP prefix, verified against startup/11-txm_motor.py.
FXI places the specimen in a flooded monochromatic field and rotates it for tomography. The diffractive optics around the sample (condenser before it, zone plate and phase ring after it) are what make this a microscope rather than a parallel-beam scanner; they are the optics 2-BM does not have.
The sample stage¶
The sample stack (class TXMSampleStage, instance zps) is the positioning core. It presents the Positioner Role.
| Axis | PV | Role |
|---|---|---|
sx |
XF:18IDB-OP{Env:1-Ax:Xl}Mtr |
sample translation X |
sy |
XF:18IDB-OP{Env:1-Ax:Yl}Mtr |
sample translation Y |
sz |
XF:18IDB-OP{Env:1-Ax:Zl}Mtr |
sample translation Z |
pi_r |
XF:18IDB-OP{TXM:2-Ax:R}Mtr |
tomography rotation (theta) |
pi_r is the tomography rotation axis and the trigger master: the Zebra reads it as encoder enc1 and emits position-compare pulses to the camera (see Controls). This is the FXI analog of 2-BM's Rotary air-bearing stage. The hardware (air-bearing vs piezo), encoder resolution, and max speed are not in the profile collection; the "PI / Physik Instrumente" reading of the pi_r name is an inference, carried confirm (STAGE-2).
The transmission-microscopy optics¶
These shape and analyze the beam through the sample. Condenser, ZonePlate, and PhaseRing are catalog Families (graduated with this deployment); BetrandLens stays a loose family name that renders as text, FXI-only (OPTIC-3).
| Optic | Family | PV axes | What it does |
|---|---|---|---|
Condenser (clens) |
Condenser | {CLens:1-Ax:X/Y1/Y2/Z1/Z2/P} |
floods the sample with monochromatic beam |
Aperture (aper) |
Aperture | {Aper:1-Ax:X/Y}, {TXM-Aper:1-Ax:Z} |
defines the illuminated field |
ZonePlate (zp) |
ZonePlate | {ZP:1-Ax:X}, {BLens:1-Ax:Y}, {TXM-ZP:1-Ax:Z} |
the objective; magnifies the transmitted image |
PhaseRing (phase_ring) |
PhaseRing | {PR:1-Ax:X/Y}, {TXM-PH:1-Ax:Z} |
Zernike phase contrast |
BetrandLens (betr) |
BetrandLens | {BLens:1-Ax:X}, {ZP:1-Ax:Y} |
conoscopic alignment aid |
The zone plate is reported in source (startup/20-global_param.py) as a NanoTools plate, 244 um diameter, 30 nm outer zone width. These are code constants, not staff-verified (OPTIC-4).
Cross-wired Y axes
In source, zp.y is wired to the {BLens:1-Ax:Y} record and betr.y is wired to the {ZP:1-Ax:Y} record: the zone-plate and Bertrand-lens Y axes are cross-wired. This is preserved faithfully in the descriptor and recorded as a Caution; do not "correct" it without confirming the real wiring with FXI staff.
Sample environment¶
A Lakeshore 336 temperature controller (XF:18ID-ES{Env:01) appears in source but is disabled (motor_lakeshore = []), so it is not modeled as a live device (ENV-1).