Preclinical evaluation of porcine colon resection using hollow core negative curvature fibre delivered ultrafast laser pulses.

<b>Figure 1</b> Schematic representation of colon tissue
layers.<b>Figure 2</b> Schematic
of the laser system for fibre delivered pulses for tissue resection<b></b><br><b>Figure 3</b> Schematic
of the laser system for direct laser resection of tissue a) Schematic of the spiral
scan pattern at the colon tissue surface during picosecond laser ablation <br><b>Figure 4</b> Seven cell NC-HCF fibre (a)
cleaved laser launching surface (b) damaged surface (c) image of light confined
in a single mode at the end face of HC-NCF (20x zoomed image) (d) single mode
beam at the focus of 20 mm focal length lens (20x zoomed image) placed after
the HC-NCF.<br><b>Figure 5</b> coupling efficiency plot of 7 cell HC-NCF<br><b>Figure 6</b> Autocorrelation traces of picosecond laser beam (FWHM = 6ps) with
an input pulse energy of ~42 µJ corresponding to ~29 µJ delivered from the output of
the HC-NCF (Blue line) showing no significant pulse broadening.<br><b>Figure 7 </b>Optical spectra of laser beam of 6 ps pulse width and 42 µJ
pulse energy. 1.5 meter long HC-NCF delivered beam with 6 ps pulse width and
~29 µJ pulse energy (blue line).<br><b>Figure 8</b> (a) and (b)
Three-dimensional surface profile of the laser ablated zone, (c) and (d)
orthogonal depth profiles of the same crater.<br><b>Figure 9</b> Haemotoxylin and eosin (H&amp;E) stained images and 3D
profilometric images of laser ablated zones in different tissues using same
laser parameters. The applied laser fluences are a &amp; c) 18 J/cm² b &amp; d)
13 J/cm² ^<br><b>Figure 10</b> The 3D profilometric image of laser ablated area using HC-NCF
delivered pulses on porcine colon samples and histology results of laser
ablated area in different tissue sample with same laser parameters a) 21 J/cm²
b) 14 J/cm² and c) 7 J/cm² laser fluences. The black line
on the image is an artefact after the preparation of sample for histology. The
expanded view of maximum thermal damage in each laser ablated tissue is
presented in the bottom.

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