Fig. 3: Non-axisymmetric luminescence observation from directional and velocity information.

a Luminescence images (left), pressure distribution profile (middle), and luminescence intensity plots (right) show quantitative changes in the shape of the luminescence signal as the velocity of the spherical indenter increases. (Scale bar, 2 mm). b, c Luminescence images (left), pressure distribution profile (right), and luminescence intensity plots (bottom) at (b) 0 and (c) 0.5 s according to the velocity change of the indenter at 1.0 N of the initial normal force. (Scale bar, 2 mm). d UCN luminescence image (left) and pressure contour map (right) change as the indenter moves in eight different directions (Scale bar, 2 mm). e Calculated skewness for a moving indenter matched the measured shear force. f Overlay of calculated skewness with the experimentally measured shear force. Source data are provided as a Source Data file.