Ultrafast laser surgery probe with a calcium fluoride miniaturized objective for bone ablation

Abstract

We present a miniaturized ultrafast laser surgery probe with improved miniaturized optics to deliver higher peak powers and enable higher surgical speeds than previously possible. A custom-built miniaturized CaF2 objective showed no evidence of the strong multiphoton absorption observed in our previous ZnS-based probe, enabling higher laser power delivery to the tissue surface for ablation. A Kagome fiber delivered ultrashort pulses from a high repetition rate fiber laser to the objective, producing a focal beam radius of 1.96 μm and covering a 90×90 μm2 scan area. The probe delivered the maximum available fiber laser power, providing fluences >6 J/cm2 at the tissue surface at 53% transmission efficiency. We characterized the probe’s performance through a parametric ablation study on bovine cortical bone and defined optimal operating parameters for surgery using an experimental- and simulation-based approach. The entire opto-mechanical system, enclosed within a 5-mm diameter housing with a 2.6-mm diameter probe tip, achieved material removal rates >0.1 mm3/min, however removal rates were ultimately limited by the available laser power. Towards a next generation surgery probe, we simulated maximum material removal rates when using a higher power fiber laser and found that removal rates >2 mm3/min could be attained through appropriate selection of laser surgery parameters. With future development, the device presented here can serve as a precise surgical tool with clinically viable speeds for delicate applications such as spinal decompression surgeries.

Ultrafast laser surgery probe for sub-surface ablation to enable biomaterial injection in vocal folds

“…Specifically, we used a 7 cell, ~ 52 μm inner core diameter, 6 m long Kagome HCPCF which exhibits low GVD (–437 fs 2 /m) and low attenuation (0.1 dB/m) at 1035 nm. The distal HCPCF length was integrated into a piezo-based Lissajous beam steering element, similar to previous studies 27 , 29 , 30 . To build the piezo-HCPCF assembly, we initially soldered leads onto the proximal end of a four-quadrant piezo-ceramic tube (EBL Photonics Inc.), coated the leads with epoxy, and diamond-turned the epoxy plug to match the inner diameter of the corresponding metal housing.…”

“…Towards clinically viable ultrafast laser surgery, various miniaturized surgical probes have been developed 25 – 30 . These probes used low NA focusing optics to enable rapid surface ablation of soft and hard tissues.…”

In vivo hamster cheek pouch subepithelial ablation, biomaterial injection, and localization: pilot study

“… 20 Further, the pulse peak power of is far below the expected critical peak power of for self-focusing in tissues, suggesting that self-focusing-induced focal plane shifting should not cause any out-of-focus damage during subepithelial ablation. 29 , 31 Given the FOV of , laser spot size of , repetition rate of 303 kHz, and frame rate of 1.11 frames per second, we generated three overlapping pulses on each point inside the FOV. 20 , 22 After ablating the full FOV, the hamster was translated laterally with a small overlap with the neighboring ablation FOV.…”

“…Toward clinically viable ultrafast laser surgery, our group has previously developed several microsurgery probes with and without image-guidance and continues to design probes. 25 – 29 …”

“…Toward clinically viable ultrafast laser surgery, our group has previously developed several microsurgery probes with and without image-guidance and continues to design probes. [25][26][27][28][29] In this letter, we demonstrate a proof of concept for the creation of subepithelial voids, injection of a biomaterial, and retention of the biomaterial inside a void using an in vivo animal model and a benchtop microscope. We used hamster cheek pouches, which are considered a good model for VF surgery because their epithelium and LP layers are very similar in composition to humans.…”