Measured and computed cross-sections of the illumination beam at various distances from the focal point, 1 measured cross-section, 2 numerically computed cross-section (offset and amplitude of the numerical data was fit to the measured data).

<p>Measured and computed cross-sections of the illumination beam at various distances from the focal point, 1 measured cross-section, 2 numerically computed cross-section (offset and amplitude of the numerical data was fit to the measured data).