Interferometric, fiber-based, real-time distance sensor for endoscopic applications

Comparison of the mechanical, flow, and optical properties of contemporary flexible ureteroscopes

Introduction: Choledocholithiasis is typically treated with endoscopic retrograde cholangiopancreatography (ERCP) and cholecystectomy. Patients with prohibitive operative risk can undergo percutaneous transhepatic cholecystostomy (PTC) drain placement, which usually is a palliative procedure. 1 These drains can be left in place indefinitely with periodic exchanges if definitive treatment is unfeasible. Surgical endoscopists can utilize the PTC drain tract to treat cholelithiasis and choledocholithiasis in these patients. Percutaneous endoscopic biliary lithectomy (PEBL) utilizes a disposable 10Fr choledochoscope with a therapeutic working channel that can accommodate various endoscopic tools and electrohydraulic (EHL) and laser lithotripsy systems. In this mini case series, we demonstrate the utility of PEBL in treating cholelithiasis and choledocholithiasis. Materials and Methods: Our first patient is a 62-year-old female with a history of pancreatic divisum complicated by multiple bouts of pancreatitis and DVT on anticoagulation who suffered a duodenal perforation during a previous ERCP necessitating Roux-en-Y reconstruction. She also underwent multiple small bowel resections and now suffers from short gut syndrome and is TPN-dependent. She presented with acute calculus cholecystitis, requiring PTC drain placement due to her altered foregut anatomy and medical comorbidities, followed by PEBL in the outpatient setting. Calculi within the gallbladder were extracted using tipless nitinol baskets, and attempts to navigate down the cystic duct were unsuccessful due to the duct’s small diameter. Post-procedure cholangiogram demonstrated no filling defects within the biliary system, and contrast flowed into the duodenum. The patient was discharged home after the procedure. The second case involves a medically and surgically complex 61-year-old male. His foregut anatomy was reconstructed as an infant, and in early adulthood, he underwent revision of his anatomy due to a bowel obstruction. The patient was unable to recall the details of either operation, and operative reports are unavailable. He presented with cholelithiasis and symptomatic choledocholithiasis. Two attempted ERCPs failed to identify the ampulla. Laparoscopic cholecystectomy was attempted and aborted due to severe adhesive disease. He then underwent PTC drain placement and three PEBL procedures in the outpatient setting. His first PEBL resulted in the basket extraction of calculi in the gallbladder and CBD. The second PEBL utilized EHL to fragment a calculus in the CBD. The third PEBL extracted some residual stone debris in the CBD. His drain was removed at the end of his third PEBL, and he was discharged home the same day. Results: The first patient returned to the emergency department one year after her PEBL procedure with acalculous cholecystitis secondary to an occluded cystic duct. She had a PTC drain placed and is currently undergoing evaluation for either surgical or endoscopic intervention. The second patient recovered uneventfully following his third PEBL procedure and has been symptom-free for 18 months. Conclusions: We demonstrate the utility of PEBL in treating cholelithiasis and choledocholithiasis in patients with prohibitive operative risk. PEBL can eliminate the need for long-term PTC drain and its associated morbidity. In patients with recurrent symptoms, replacement of a PTC drain can afford patients the opportunity for repeat endoscopic interventions or serve as a bridge to surgical intervention. Disclosures: Eric D. Moyer, MD—None. McKell Quattrone, MD—None. Samuel Zolin, MD—None. Eric M. Pauli, MD, FACS, FASGE—Speaking/teaching: Bard Davol, Medtronic, Ovesco. Consultant: Boston Scientific Corp., Actuated Biomedical, Inc., Baxter, Cook Biotech, Neptune Medical, Surgimatrix, CMR Surgical, Boehringer Laboratories, Allergan. Royalties: UpToDate, Inc., Springer. Financial Interests: IHC Inc, Contamination Source Identification, SIG Biomedical. Joshua Winder, MD, FACS—Consultant: Boston Scientific Corp. Consents. Author(s) have received and archived patient consent for video recording/publication in advance of video recording of procedure. Runtime of video: 09 mins 56 secs.

A simple configuration dual-wavelength fiber laser, by combining the first-order Brillouin laser and the residual pump laser, is proposed and experimentally demonstrated. A 1 km long single-mode fiber is used as the stimulated Brillouin scattering gain medium pumped by a narrow linewidth tunable laser source (TLS). Through simply adjusting the TLS output power, power-equalized dual-wavelength lasing can be achieved with a high optical signal to noise ratio (OSNR) of >80 dB. With the good tunability of the TLS, the dual-wavelength fiber laser has a tunable range of ∼130 nm, and simultaneously the beat frequency of the two lasing wavelengths can be tuned from 10.1875 to 11.0815 GHz with the tunable range of 0.8940 GHz. The high stability of the dual-wavelength operation is experimentally verified by the measured beat frequency fluctuation of ≤6 MHz in 1 h and power fluctuation of ≤0.03 dB in 2 h. The temporal characteristics of the fiber laser are also investigated experimentally. The fiber laser will find good applications in fiber sensing and microwave photonics areas.

To compare two newly designed flexible ureteroscopes with their respective predecessors, to determine whether design advances have overcome the limitation of tip deflection, which may interfere with diagnosis and treatment of lower pole renal pathology. Two new-generation flexible ureteroscopes, the DUR-8 Elite (ACMI, Southborough, MA, USA) and 11278AU (Karl Storz Endoscopy, Culver City, CA, USA) were compared with their previous models, the ACMI DUR-8 and the Storz 11274AAU. Active tip deflection and irrigation flow rates with and without various endoscopic tools were assessed. Specifications, purchase prices and repair costs were obtained from each manufacturer. The field of view and screen image size of each ureteroscope were also compared. The ACMI DUR-8 Elite and the Storz 11278AU had improvements of 79 degrees and 144 degrees, respectively, from their respective older models. Although the tip deflection of all ureteroscopes was compromised by inserting different endoscopic tools, these new instruments were less affected. With a 3 F basket inside the working channel, the ACMI DUR-8 Elite and the Storz 11278AU had only 0.7% and 2.8% loss of upward tip deflection, compared with their older models, at 9.6% and 5.0%, respectively. However, the flow rates of these new instruments were decreased. The new flexible ureteroscopes have significantly better active tip deflection than previous models, both with and without endoscopic instrumentation inserted. However, improved flexibility is at the expense of decreased flow rates and higher purchase costs.

A wideband tunable optoelectronic oscillator (OEO) based on a dispersion compensated phase modulated microwave photonics filter (MPF) is proposed and experimentally demonstrated. The MPF, consisting of a tunable laser source (TLS), a phase modulator, a fiber Bragg grating Fabry–Perot filter and a photodetector, is used as the oscillating mode selection device. Dual-loop configuration is employed to make sure the OEO operates at a single oscillating mode. Theoretically analysis is carried out to demonstrate the tuning range limitation due to the phase-modulation to intensity-modulation conversion caused by long single mode fiber (SMF). To overcome this disadvantage and expand the signal tuning range, a dispersion compensation fiber is introduced followed by the SMF to compensate the fiber dispersion. By simply adjusting the wavelength of the TLS, an ultra-wideband tunable microwave signal with the frequency tuning range from 2 to 44 GHz is obtained. The phase noise is also investigated and measured to be less than − 110 dBc/Hz at an offset of 10 kHz within the whole frequency range.

Endoscopes for use in ophthalmology can be manufactured with diameters smaller than 0.89 mm. Because gradient-index (GRIN) lenses yield a higher resolution than ordered fiber bundles having the same diameter, GRIN lenses with a diameter of either 0.35 mm or 0.50 mm were utilized to manufacture thin high resolution endoscopes. Whatever the working distance, the resolution obtained with a GRIN lens having a diameter of 0.50 mm was higher than that obtained with a GRIN lens of 0.35 mm. Thanks to the miniaturization, an additional working channel could also be integrated within the endoscope. This allowed new combinations of various surgical instruments. This channel can be used as a guide for an optical fiber for laser therapy or as an irrigation/aspiration channel. The use of such an instrument where the observation path is parallel to the surgical instrument was compared to the application of the endoscope as a separate monitoring system. The advantages and inconveniences of both systems are discussed. Preference is given to a system where the diameter of the observation channel is maximum and the optical fiber for laser delivery is integrated but adjustable along its length within the endoscope.

A large-capacity ultra-weak fiber Bragg grating (UW-FBG) array interrogation system is proposed and implemented. The system utilizes time- and wavelength-division multiplexing methods, based on a large-range tunable laser source (TLS) with fast tuning capability. The TLS consists of a distributed feedback multi-wavelength laser array (DFB-MLA) with a wavelength tuning range of 40 nm, which is realized using the reconstruction-equivalent-chirp (REC) technique. An external SOA modulator is used to modulate the output light from the TLS into nanosecond pulsed light. We establish an experimental system and successfully achieve 50 UW-FBGs interrogation. We perform temperature, strain, and vibration sensing experiments with a interrogation linearity of above 0.9995 and an error of less than 4 pm. Theoretically, the system is estimated to have an interrogation capability of more than 10,000 UW-FBGs, and the minimum spacing of adjacent UW-FBGs is 0.4 m. This research has made significant advancements in the multiplexing capability and spatial resolution of the UW-FBG array interrogation technology, offering important application potential in fields such as battery pack, structural health monitoring, and aerospace.

A multi- wavelength comb is demonstrated using a four-wave mixing effect in a linear cavity resonator consisting of photonics crystal fiber (PCF) and a bi-directionally pumped Bismuth-based Erbium Doped Fiber (Bi-EDF). The comb is generated in 1585 nm region with assistance of the pump signal from Tunable Laser Source (TLS) with a line spacing varies from 0.34 to 0.39 nm. A stable output laser comb of 14 lines is obtained using a 80/20 coupler to inject the TLS signal and a total 1480 nm pump power of 270 mW.

In 2018 Arthur Ashkin shared half of the Nobel prize physics for the optical tweezers and their application to biological Indeed, Optical Tweezers (OT) have found relevant applications in bioscience, thanks to the capability of trapping and manipulating small entities like viruses, bacteria, and DNA strands, in a non-destructive way. The balance of optical forces creating a stable all-optical trap is usually achieved by focusing a Gaussian beam with a high-NA microscope objective. Nevertheless, more efficient optical traps can be obtained by focusing a donut annular beam instead of a Gaussian beam [1], particles larger than the focused beam size. Additionally, the need bulky high-NA optics such as microscope objective may limit the use of OT in potential applications, like in-vivo trapping, and prompts the development of optical fiber-based OT. Here, we 3D printed a hybrid micro-optical structure on a single-mode optical fiber to create an ultra-compact annular beam fiber tweezer [2], with long working distance and a small probe diameter. A cascade of refractive, reflective, and waveguiding optical elements are microfabricated in a single step to transform the beam output from the fiber. The sequence is constituted by a gaussian to annular waveguide converter, a reflective annular beam expander, and a lensed prism deflector. The gaussian to annular waveguide converter transforms the single-mode fiber output into an annular beam with an inner radius of 4.5 µm and an outer radius of 9 µm. Then, a reflective inverted truncated cone expands the annular beam to an inner radius of 47 µm and an outer radius of 57 µm, by two total internal reflections. Afterward, a total internal reflection prism focuses the annular beam along its radius with a numerical aperture of 1 in water immersion. The output surface has a rounded profile with a radius of curvature of 7 µm to create a lens with a focal length of 50 µm that focuses the annular beam at the trapping point. All the total internal reflection surfaces are designed to work in water immersion, where the critical angle is around 60deg. The final result of this cascaded micro-optical structure is a sharply focused annular beam which forms an optical trap with a working distance of 30 µm. The microstructure is 275 µm long with a diameter of 116µm, smaller than the single-mode optical fiber which has a diameter of 125 µm. The structure has been 3D printed with a commercial Two-photon lithography system (Photonic Professional GT, Nanoscribe GmbH), by using the proprietary material Ip-Dip (Nanoscribe). We demonstrate the all-optical 3D trapping capabilities of this device by trapping polystyrene beads with different diameters. This device demonstrates the potential of 3D printing through two-photon lithography as a flexible tool to realize complexly integrated micro-optical systems. [1] O'Neil, A.T., Padgett, M.J., 2001. Axial and lateral trapping efficiency of Laguerre–Gaussian modes in inverted optical tweezers. Optics Communications, 193(1-6), pp.45-50. [2] Liberale, C. et al. Miniaturized all-fibre probe three-dimensional optical trapping and manipulation. Nature Photonics, 1(12), p. 723.

A monolithic tunable single mode terahertz quantum cascade laser source based on intra-cavity difference frequency generation with a tuning range of ~580 GHz is demonstrated at room temperature.

Broadly tunable compact visible laser sources in the spectral region of 500–650 nm are valuable in biophotonics, photomedicine and for many applications including spectroscopy, laser projection and confocal microscopy. Unfortunately, commercially available lasers of this spectral range are in practice bulky and inconvenient in use. An attractive method for the realization of portable visible laser sources is the frequency-doubling of the infrared laser diodes in a nonlinear crystal containing a waveguide [1]. Nonlinear crystal waveguides that offer an order-of-magnitude increase in the IR-to-visible conversion efficiency also enable a very different approach to second-harmonic generation (SHG) tunability in periodically-poled crystals, promising order-of-magnitude increase of wavelength range for SHG conversion. This is possible by utilization of a significant difference in the effective refractive indices of the high-order and low-order modes in multimode waveguides [2]. The recent availability of low-cost, good quality semiconductor diode lasers, offering the coverage of a broad spectral range between 1 μιη and 1.3 μπι [3,4], in combination with well-established techniques to fabricate good quality waveguides in nonlinear crystals, allows compact tunable CW laser sources in the visible spectral region to be realized [2].

Wideband tunable linear-cavity fiber laser source using strain-induced chirped fiber Bragg grating

The linewidth characteristic of a commercial tunable laser source (TLS) is experimentally demonstrated with two different linewidth measurement methods; homodyne and heterodyne detections. With 25km of SMF as a delay fiber and wide mode operation, the linewidths of 124 MHz, 114 MHz and 176 MHz are obtained at operating wavelengths of 1530 nm, 1540 nm and 1560 nm, respectively. The linewidth of the TLS is obtained at around 10 MHz and 150 MHz for narrow and wide modes, respectively with heterodyne technique.

In conclusion, a TTD beamforming system that can provide continuous beam steering using a tunable multiwavelength laser source with equally increased or decreased wavelength spacing has been proposed and experimented. The experimental results showed when the wavelengths were tuned with equally increased wavelengths spacing, equally increased time delays were obtained.

Development of a micro-imaging probe for functional brain imaging