In localized TPET the laser line-focus is a movable heater; this panel is an illustrative synthetic location-response model, not digitized experimental data. Drag the heating-position slider along the suspended fiber and watch two things at once: the small diagram shows where the line focus sits, and the plot accumulates the late-window extracted diffusivity at every position you have visited. Away from the ends the extracted value holds flat inside the tolerance band — different heating positions excite the mode spectrum differently, but the late-transient decay rate the reduction measures belongs to the geometry and material, not to where the heat entered. Near the heat-sunk ends the extraction degrades, exactly where the localized-source model says the valid fit window shrinks.
Model: an illustrative SYNTHETIC location response, position-independent late-window extraction across the central region (the slowest-mode decay is a property of geometry and material), with a smooth normalized departure applied within roughly the outer 20% near each heat-sunk end, plus independent Gaussian noise per extraction. The published localized line-source campaign reported the same qualitative pattern: central-region robustness with degraded extraction near the ends. Axes normalized; schematic teaching tool, not an instrument.