untethered atom · In-situ FAQ

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In-situ testing FAQ

For when the grain was perfect and the specimen still came out sideways.

Grain choice, stage rotation, and the angles nobody ever subtracts, each answer linked to the planner that works through it.

Which Grain Do I Lift Out? Open the interactive planner →

Can I just redefine ND during acquisition and then pick a grain that matches?

No. ND is the physical surface normal of your sample, not a software setting. The acquisition geometry only decides which frame the numbers are written in: re-labeling the frame changes every Euler angle and moves no atoms. The angle between a grain's crystal direction and the real surface is the same in every honestly recorded frame, and that is the angle your specimen inherits. If you make the tilt physical instead (a wedge stub, or re-polishing the surface at an angle), you have simply bought the leaning-geometry trade with glue instead of stage tilt: the milled shape is square to the stage but not to the surface, one wedge angle serves exactly one direction for the whole sample, and it must be tracked to a fraction of a degree or every azimuth in your map is wrong. Meanwhile a polycrystalline map already contains almost every inclination for free. Picking the right grain IS the cheap, honest version of tilting the sample. See it worked out on the planner →

What does R★ actually mean?

Nothing about the crystal. It is the stage dial reading at which your chosen grain's feature faces the milling pattern. If the sample had been glued to the stub 30° differently, R★ would read 30° differently and the finished specimen would be identical. The number carries no meaning on its own; only the alignment it produces does. Scrub R yourself on the planner →

What does the stage rotation achieve, physically?

Rotation spins the sample flat about its own normal, so it can point a feature around the compass but can never tip it up or down. For a foil, pointing is everything: the rotation turns the zone axis square across the future foil, and the dip in the planner's R curve is that alignment happening. For a pillar or cantilever the vertical requirement never cares about R at all; it was settled the moment you picked the grain. That is what the flat line in the plot is telling you. Watch the R curve on the planner →

Why not tilt the stage a few degrees and put the axis dead on the beam?

You can, and the planner's recipe footnote gives you the exact trim value. The price is a specimen that leans out of the surface: a pillar your flat punch meets at an angle, a foil that does not stand vertical. The planner spends grain choice instead of tilt so the geometry stays standard, and the leftover angle goes where it is cheap: the TEM holder's α for a foil, the budget you set for a pillar or cantilever. Compare the two on the planner →

Does it matter how the sample happens to sit on the stub?

Only as bookkeeping. Mounting orientation and stage rotation add up inside one and the same term, so any remount just slides R★ by the same amount and the physics is untouched. One fiducial mark tying the map to the physical sample is all the calibration a liftout needs. See the fiducial step on the planner →

Do I subtract the 70° EBSD tilt, or the 52° milling tilt, from my orientation data?

Never. The EBSD software already reports orientations in the sample frame with the 70° acquisition tilt removed, and the 52° milling tilt is chamber geometry, not crystallography. Neither number ever touches your Euler angles; the planner's step 1 exists to make exactly that point. See both geometries drawn to scale →

Two grains have almost the same Euler color, so they are almost the same orientation, right?

Not necessarily. Euler space wraps around, and one orientation can have several equivalent angle triplets, so two look-alike colors can be very different crystals and two different colors can be the same crystal. Use the Euler view to read numbers off the map; judge orientation at a glance with the IPF view. Flip between the two views on the planner →

Which holder tilt fixes the leftover δ once the lamella is in the TEM?

Whichever axis your weld put along the lamella. The leftover angle is a rotation about the lamella's long axis; the stage rotation already squared the zone axis across the foil, so there is nothing left to fix in that direction. Clamp the grid with the long axis along the holder rod and α absorbs all of δ; clamp it across the rod and the whole correction lands on the smaller β tilt, which may not reach; in between it splits. That makes the weld orientation on the grid a real decision, not a convenience, and it is why the habit of welding along the rod is worth building. Set the clamp angle and read the exact walk on the planner →

What if no grain in my map is within budget?

Map more area: every new grain is a fresh draw of orientations, and the more grains you map, the closer the best one sits to your target. If the budget still cannot be met, loosen it consciously (the planner's deviation window shows exactly what each degree costs), or reconsider the target: some combinations are limited by crystallography itself, and the validator will have told you so. Check your own map on the planner →