Figure 1

Schematic of electron matter waves diffracted by a circular aperture and focused by a lens with astigmatism. The Gouy phase anomaly describes the variation in the electron wave phase along the longitudinal (vertical) optic axis, through the transverse center of the aberrated focal volume as compared to the linear variation of phase predicted by geometric optics. A thin specimen is used to correct imaging lens aberrations with a parallel probe, prior to the imposition of astigmatism in the illumination and focusing of the probe in the specimen plane. The parameter $u$ is proportional to the distance along the optic axis as described in the paragraph containing Eq. (1).Reuse & Permissions

Figure 2

(a) Retrieved electron phase map at a focal distance in-between the two astigmatic focal lines. (b) Corresponding propagated intensity. (c) Experimental intensity distribution at the same focal distance. (d) Retrieved electron phase map near one of the astigmatic focal lines. (e) Corresponding propagated intensity. (f) Experimental intensity distribution at the same focal distance. The arrow in (b) highlights an outlying discrepancy in the retrieved probability density, discussed in the main text.Reuse & Permissions

Figure 3

Experimentally retrieved on-axis phase (dashed curve) for a focused astigmatic matter-wave field compared with the Gouy anomaly theory predicted by Visser and Wolf [14]. Two sequential phase shifts of π/2 rad occur at each line focus due to the Gouy anomaly. Parameters required for the theory given by Eq. (1) were measured from the experimentally retrieved intensity distributions alone.Reuse & Permissions

Figure 4

Electron probability density measured from a through-focus series of 32 images, which were stacked along the vertical direction and were interpolated. The uncertainties along two transverse directions, orthogonal to each line focus, were calculated from each image. The paraxial electron wave evolves slowly along the optic axis as evidenced by the 10-nm transverse scale bar, which is to be contrasted with the micron-scale focal range along the vertical axis.Reuse & Permissions