Fig. 2.

(a) Intensity profile of a beam focused to a 33 µm spot size (1/e² beam diameter) using a standard focal geometry. (b) Integrated intensity contours along the axial dimension of the focus without SSTF (black) and with SSTF (red). (c) Intensity profile of a beam with an SSTF focusing geometry also focused to a 33 µm spot size. The beam aspect ratio, ${\beta }_{BA}$, is 11.