Fig. 1. Schematic of angle amplification by CF. (a) Comparison of divergence angles between conventional fiber and CF. (b) Schematic angle amplification at the conical tip of the CF. (c) Relationship between θoutAM and θin for cone angles ranging from 10° to 100° using the model. (d) Relationship between θoutAM and θin for CFs at several representative angles (ψ=19.7°,35.7°,29.1°,88.9°) using the model. (e) Physical image and actual exit light distribution of CFs at the corresponding angles (ψ=19.7°,35.7°,29.1°,88.9°).

Fig. 2. (a) Bright-field–LSCI dual-mode imaging system diagram and (b), (c) CF fixed on the laparoscope schematic diagram. (b-1) Longitudinal cross section of a CF affixed to a 0° viewing angle laparoscope within a 0° tube; (b-2) longitudinal cross section of 0° viewing angle tube; (c-1) longitudinal cross section of a CF affixed to a 30° viewing angle laparoscope within a 30° tube; (c-2) longitudinal cross section of 30° viewing angle tube.

Fig. 3. Illumination characteristics of MFBL and CF. Images of a standard Lambertian phantom under laser illumination using (a) MFBL and (b) CF at the WD=50  mm. (c) Comparison of illumination field of view (as depicted in Section 2.E); (d) speckle contrast; (e) 1/K2 uniformity; (f) output power and coupling efficiency under laser illumination using MFBL and CF. Scale bar in (b): 10 mm. WD, working distance.

Fig. 4. Phantom experiments with CF and MFBL laser illumination. (a) 1/K2-velocity measurements with CF and MFBL laser illumination at various working distances; (b) linear fit (R2) of 1/K2 and velocity under MFBL and CF laser illumination at various working distances; (c) velocity measurement sensitivity (η) under MFBL and CF laser illumination at different working distances.

Fig. 5. Original speckle pattern and LSCI with MFBL and CF laser illumination of rats. (a) Original speckle pattern under MFBL laser illumination; (b) original speckle pattern under CF laser illumination; (c) LSCI under MFBL laser illumination; (d) LSCI under CF laser illumination. Scale bar in (d): 10 mm.

Fig. 6. Ischemia–reperfusion experiments in rats. (a) Bright-field imaging before (a-1), during (a-2), and after ligation (a-3). (b) Endoscopic LSCI under MFBL laser illumination before (b-1), during (b-2), and after ligation (b-3). (c) Endoscopic LSCI under CF laser illumination before (c-1), during (c-2), and after ligation (c-3). (d) 1/K2 of four representative ROI points before, during, and after ligation under MFBL and CF laser illumination. (e) 1/K2 of five representative ROI points throughout the ischemia–reperfusion process under CF laser illumination. Scale bar in (c-3): 10 mm.

Fig. 7. Enlarged view of the black, white, and red boxes in Fig. 6(b). (a), (b) LSCI of the regions of ischemia–reperfusion under MFBL (a) and CF (b) laser illumination. (c), (d) LSCI of the main vessel under MFBL (c) and CF (d) laser illumination. (e), (f) LSCI of the distal branch vessel under MFBL (e) and CF (f) laser illumination. (g) 1/K2 fitting along the designated white line in (c) under MFBL and CF laser illumination. (h) 1/K2 fitting along the designated white line in (e) under MFBL and CF laser illumination.