Flexible Laser Research Articles

NEW TECHNOLOGIES AVAILABLE FOR MICRONEUROSURGICAL REMOVAL OF ACOUSTIC NEUROMAS

Introduction The aim of this study was to analyze the results of microsurgery removal of acoustic neuromas (AN) using new technologies: flexible hand-held laser fiber, Sonopet Ultrasound Aspirator, Facial Nerve “detector” monopolar stimulation (for localize position and course of facial nerve), BAER’s with level specific (LS) CE-Chirp stimulus for hearing preservation, endoscope for IAC final check, and injectable bone substitute for closure. We report a retrospective nonrandomized clinical study on 300 cases consecutively operated on. Material and Methods From July, 2010 to December, 2023, 350 consecutive patients suffering from AN have been operated on with microneurosurgical technique by key-hole retrosigmoid approach. In majority of cases tumor resection was performed with the aid of a handheld flexible laser fiber. In the same period, Sonopet Ultrasound aspirator was used for tumor debulking and/or opening of the internal auditory meatus and canal. From May 2015, hearing preservation by means LS CE-Chirp BAER was attempted in patients with preoperative socially useful hearing (AAO-HNS class A and B). In addition, we check the removal of tumor inside the internal auditory canal (IAC) by using the flexible and/or rigid endoscope, for completing tumor removal near the fundus. Results Overall time from incision to skin suture changed in relation to size of tumor (from 165 to 575 minutes) and was not affected by the use of hand-held laser. Facial nerve function was clinically assessed with the House-Brackmann (HB) scale preoperatively, in the early postoperative period (after 1 week), and at 6-month follow-up. In 3 cases a preoperative facial nerve palsy was observed (HB III and HB IV, respectively). In the remaining cases, 6 months after surgery facial nerve preservation rate (HB I) was 92%, Hearing preservation rate (AAO-HNS A and B, pre- and postoperatively) was 52% in eligible cases. Total and “nearly total” removal of tumor was possible in about 80% of cases. Dura closure was performed with underlaying autologous pericranium. Injectable bone substitute in the gaps after bone flap repositioning minimized postoperative CSF leakage and improved the aesthetic result. Conclusions The use of new technologies (handheld flexible laser fibers, Sonopet Ultrasound Aspirator, fluoreceine, Nimbus facial nerve continuous monitoring, LS CE-Chirp BAER, endoscope for IAC final check) in AN microsurgery seems to be safe and efficacious and facilitates tumor resection, especially in ‘‘difficult’’ conditions (e.g., large size, highly vascularized, or hard tumors). The good functional outcome following conventional microsurgery seems to be further improved and the extent of tumor removal could be increased with the proper use of the new technologies available in the neurosurgical armamentarium.

Complementary Superwetting Structures Treated by a Femtosecond Laser for Simultaneous Spontaneous Directional Transport of Water Droplets and Underwater Bubbles.

The control of fluid transport is crucial and has broad applications in the fields of intelligent systems and microfluidics. However, current studies usually focus on the spontaneous directional transport of a single type of fluid or require complex preparation processes. In this paper, the single femtosecond laser direct processing of complementary superwetting structures using polyimide/polytetrafluoroethylene is proposed, for the first time, to realize simultaneous spontaneous directional transport of water droplets and underwater bubbles without any additional energy or chemical treatment. The flexible laser fabrication enables the creation of diverse transport structures, facilitating the achievement of linear and curvilinear fluid transport on superwetting structures. In addition, relevant applications in self-transporting chemical reactions and bubble switching are presented. This technique provides a novel approach to fabricate patterned superwetting surfaces for applications in intelligent transport, microbiology, and chemistry.

Influence of intensity distributions on the process dynamics during laser deep penetration welding of pure nickel with a flexible ring mode laser source

Current research results demonstrate the potential of spatter reduction in laser deep penetration welding by using adapted laser beam intensity distributions between a ring and a core intensity. The spatter-reducing effect, resulting from the additional ring intensity, is often attributed to an enlarged keyhole opening. However, it remains a matter of debate how exactly an additional ring intensity influences the process. This study, therefore, investigates the effect of an increasing ring intensity on process dynamics and the spatter formation regime. Laser beam welding experiments were carried out on 2.4068 nickel hidden T-joints at different welding speeds of up to 16 m/min, as well as different intensity distributions, while maintaining a constant weld depth. The tests were evaluated by using two high-speed cameras from different angles to analyze spatter and their formation mechanisms as well as the keyhole opening. Metallographic analyses and x-ray images were used to determine influences on the seam shape and porosity. It was shown that a change in intensity distribution has a significant influence on the melt flow, the resulting amount of spatter, and the porosity, which is comparable across the investigated welding speeds. While a core-based power distribution leads to spatter formation on the rear of the keyhole opening, it was shown that a ring-based power distribution leads to spatter formation on both sides of the keyhole. With an optimal power distribution, spatter formation could be largely prevented. Based on these findings, the single wave regime, a stabilized regime, and a lateral spatter regime were identified.

Novel scoring system for predicting stone-free rate after flexible ureteroscopy lithotripsy.

This study aims to investigate the factors affecting the stone-free rate (SFR) of flexible ureteroscopy and laser lithotripsy (fURSL) for renal stones and establish predictive models by identifying their prognostic factors. We retrospectively examined 252 patients with renal stones who were treated with fURSL between July 2020 and April 2022. We analyzed the relationship between the patient's clinical data (sex, age, and body mass index), stone status (side, size, location, stone/transverse process pixel ratio [STPR], and the CT value of stone [SCTV]), and SFR to determine the relevant factors and analyze their influence. Additionally, a nomogram was constructed based on these prediction results. A total of 252 patients were enrolled based on the inclusion and exclusion criteria. They were reviewed 7, 30, and 90 days postoperatively, with 46, 23, and 10 patients failing to discharge stones, respectively. Univariate Cox proportional hazard regression results revealed that the SFR was correlated with stone location, diameter (D1, diameter of stone measured by computed tomography [CT]; D2, diameter of stone measured by kidney-ureter-bladder abdominal radiography), SCTV, STPR, and operation time. Multivariate Cox proportional hazard regression was used to develop 2 predictive models for the SFR. The influencing factors of model 1 included D1, location, and SCTV, whereas those of model 2 were D2, location, and STPR. The results are shown in the nomogram. Receiver operating characteristic curves showed no significant difference between models 1 and 2 (P = .498), indicating that the nomogram was highly predictive. After 1000 resamples and internal self-validation, the C-indices of models 1 and 2 were 0.924 and 0.895, respectively, showing that the stone clearance predicted by the nomogram matched the actual situation. Stone location, size, and density (SCTV and STPR) were significant predictors of SFR after fURSL. The scoring system based on these factors may be used to guide optimal treatment strategy selection.

Compact multi-ring perfect vortex beam generator fabricated by laser direct writing

Perfect vortex beams (PVBs) have received much attention in recent years since the annular intensity distributions are independent of the topological charge (TC). However, the cost-effective preparation of micrometer-scale monolithic devices capable of generating multiple PVBs through a simple approach remains a significant challenge. In this work, a design of double-ring perfect spiral phase plates (DPSPPs) is presented for the generation of PVBs at two distinct locations along the radial direction. The respective radii and spacing of the double-ring PVBs can be tuned by changing the control parameters. The proposed DPSPPs are fabricated by the flexible femtosecond laser direct writing (FsDLW) technique. The experimentally generated double-ring vortex beams with different TCs possess an almost constant radius, which is consistent with the characteristics of PVBs. Furthermore, the double-ring PVBs with different fractional and trigonometric function TCs and the multi-ring PVB are also demonstrated. The design and fabrication methods are expected to facilitate the miniaturization of the applications of PVBs in optical manipulation, optical communication, and high-capacity information storage.

High pressure and high temperature Brillouin scattering measurements of pyrope single crystals using flexible CO2 laser heating systems

Single-crystal Brillouin scattering measurements are important for interpreting seismic velocities within the Earth and other planetary interiors. These measurements are rare, however, at temperatures above 1000 K, due to the fact that the transparent samples cannot be heated by common laser heating systems operating at a wavelength on the order of 1 μm. Here we present Brillouin scattering data on pyrope collected at pressures up to 23.8 GPa and temperatures between 850 and 1900 K using a novel CO2 laser heating system confined in either a flexible hollow silica waveguide or an articulated arm with mirrors mounted in each junction to direct the laser to the exit point. Pyrope has been chosen because it has been extensively studied at high pressures and moderate temperatures and therefore it is an excellent sample for bench-marking the CO2 laser heating system. The new high-temperature velocity data collected in this study allow the room pressure thermal parameters of pyrope to be constrained more tightly, resulting in values that reproduce the temperature dependence of the unit-cell volume of pyrope measured in recent studies at ambient pressure. Aggregate wave velocities of pyrope calculated along an adiabat using the thermoelastic parameters determined in this study are larger than those obtained using published values, implying that velocities for many mantle components may be underestimated at mantle temperatures because high temperature experimental data are lacking.

First clinical evaluation of a flexible digital ureteroscope with direct in scope suctioning system (Pusen DISS 7.5Ch): prospective multicentric feasibility study.

A new digital single-use flexible ureteroscope, Pusen direct in scope suction (DISS) 7.5Fr (PU3033AH), was evaluated with respect to manoeuvrability, suction quality, visibility and clinical efficiency. A prospective cohort study was conducted in six tertiary reference centers in Europe and Asia between February-April 2024. Adult patients who underwent flexible ureteroscopy and laser lithotripsy (fURSL) for urolithiasis were included. Demographic, intraoperative and follow-up characteristics were recorded. Quality parameters were rated by each surgeon using a Likert scale. a total of 57 fURSL were performed. Preoperative characteristics revealed a mean stone volume of 480.00mm3 (mean Hounsfield Unit- 998). 57.9%(n = 33) of the patients were pre-stented, and a ureteric access sheath was used in 64.9%(n = 37). Integrated-suction was deemed helpful in 94.7%(n = 54) fURSL as reported by the operators. An initial stone free rate (SFR) confirmed by postoperative imaging was achieved in 84.21%(n = 48). Quality parameters of the scope reached a mean Likert score of 4.5, with a "very good" mean evaluation for "scope placement", "visual quality", "irrigation", "deflection", "manoeuvrability", and "weight". "Suction quality" and "overall performance satisfaction" were rated "good". Comparing the Pusen DISS scope with other previously used scopes, overall satisfaction was rated 4.1. When asked if the surgeons would be willing to use the Pusen DISS 7.5Fr scope in the future, all the six surgeons answered positively. The DISS 7.5 Pusen ureteroscope displayed good visibility, manoeuvrability and suction quality, with excellent operative results. Further evaluation with larger comparative cohorts will help understand the potential of in-vivo use of integrated suctioning systems for fURSL.

Efficacy of flexible ureterorenoscopy in treating multiple renal stones: a cohort study.

While the efficacy of flexibleureterorenoscopy (URS) in managing solitary kidney stones (KSs) is widely acknowledged, its effectiveness intreating multiple stones has scarcely been investigated. This study aims to assess the effectiveness and safety of retrogradeintrarenal surgery (RIRS) utilizing flexible URS and laser lithotripsy in the management of multiple KSs. Methods: This study was a single-group cohort study conducted on patients with multiple KSs who underwent treatment withRIRS using flexible URS and laser lithotripsy. Stone-free status was considered as the lack of residual stone fragments or anyresidual stone of any size. The first follow-up appointment was arranged 3-4 weeks following the procedure. If significant residualstones were present, patients underwent reintervention within 2-4 weeks. A total of 110 patients with multiple KSs were included. The mean stone burden was 27.5 ± 7.9 mm, and the mean duration of the operation was 54.9 ± 19.7 minutes. Seven cases(6.3%) experienced intraoperative complications, while postoperative complications were found in eight cases (7.3%). Afterfour weeks, a stone-free rate (SFR) was documented in 80.9% of the cases, and this rate increased to 93.6% after three months.The SFR after three months was significant with Guy's stone score (p < 0.001); however, it did not reach a significant level with any other parameters. Conclusions: The RIRS with flexible URS may be an effective and potentially safe procedure for treating multiple KSs. It mayyield a favorable SFR with an acceptable complication rate.

The efficacy of flexible ureteroscopy for large volume stones and hazards of ureteral access sheath usage: A prospective randomized study

ABSTRACT Objectives We aimed to assess the stone free rate of flexible ureteroscopy and laser lithotripsy (FURL) in upper urinary tract stones (UUTS) >20 mm and the risk of complications from ureteral access sheath (UAS) usage. Methods This is a prospective randomized clinical trial that included patients with UUTS larger than 20 mm who underwent FURL after randomization into two groups: group A (UAS) and group B (non-UAS). Data were collected for patients’ demographics, stone parameters, operative and postoperative complications, and the outcome of FURL regarding stone-free rate (SFR) and perioperative complications, with a 6-month follow-up. Stone clearance was defined as the absence of fragments or the presence of fragments smaller than 2 mm on follow-up CT scans of the urinary tract (CTUT). Results One hundred and fifty-nine patients were evaluated. The mean stone size was 27.08 ± 6.185 mm. Complete stone-free status was achieved in 84.9% of the patients. No significant difference was detected between both groups regarding operative time or SFR. The ureteric injury was identified in 13 (8.1%) patients (10 in group A and 3 in group B, p: 0.0481). Five of them, from group A, revealed hydronephrosis after stent removal. Postoperative pain and fever were documented in 50 and 22 patients, respectively, without significant differences between both groups. Postoperative sepsis occurred in 7 patients (2 in group A, 5 in group B, p: 0.380) who required supportive care. Conclusion FURL without UAS is a safe and efficient treatment for upper urinary tract stones larger than 20 mm in the form of lower risk of ureteric injury.

Comparison of Moses laser and Raykeen laser in patients with impacted upper ureteral stone undergoing flexible ureteroscopic holmium laser lithotripsy

BackgroundTo compare the operative effect and clinical efficacy of the Moses laser mode and the Raykeen holmium laser energy platform powder mode under flexible ureteroscopic lithotripsy in patients with impacted upper ureteral stones.MethodsFrom March 2022 to September 2022, 72 patients were divided into a Moses laser group and a Raykeen laser group according to surgical method, with 36 patients in each group. CT and ureteroscopy confirmed that all patients had isolated impacted upper ureteral stones. The stone volume (mm3), stone density (Hu) and severity of hydronephrosis were measured by CT. Postoperative complications were evaluated using the Clavien–Dindo score.ResultsThere were no complications of ureteral stenosis related to the laser treatment. The operative time and lithotripsy time were lower in the Moses laser group than in the Raykeen laser group (P < 0.05). The stone-free survival rate did not differ significantly between the two groups (P = 0.722). Stone volume was found to be positively correlated with laser energy and lithotripsy time in both groups (P < 0.01). There was no significant correlation between laser energy and lithotripsy time or ureteral stone density (Hu) in the Moses laser group (P > 0.05) or the Raykeen laser group (P > 0.05).ConclusionsThe contact mode of Moses technology and the powder mode of Raykeen laser lithotripsy can be used for the ablation of a single impacted upper ureteral stone. The ablation speed was related to the stone volume and the severity of polyp hyperplasia, not the stone density. We recommend the use of the powdered mode as a therapeutic measure for the treatment of impacted upper ureteral stones in flexible ureteroscopic lithotripsy.

Research on flexible and fast tunable laser in coherent optical communications

A flexible and fast tunable laser based on hybrid integration is proposed, which can realize single and multi-wavelength reconfigurable output by controlling the on or off of semiconductor optical amplifiers (SOAs) array in combination with a tunable arrayed waveguide grating (AWG). The wavelength switching time achieves <0.8 ns. The stable output power of the tunable laser is >16 dBm with >70 dB side mode suppression ratio (SMSR) and 6.4 nm tunability. The designed laser exhibits narrow linewidths down to 1 kHz and longitudinal mode spacing of 0.8 nm, which is suitable for ITU-T standards and the output power meets the requirements of coherent optical communications. A broadened spot-size converter (SSC) for bi-directional transmission is designed and implemented with a power coupling efficiency about 0.93 and an optical bandwidth of more than 200 nm. Demonstration of the 100 Gb/s quadrature phase shift keying (QPSK) self-homodyne coherent optical transmission based on designed laser is achieved.

The Significance of Stone Culture in the Incidence of Sepsis: Results from a Prospective, Multicenter Study on Infections Post Flexible UreteroreNescopy (I-FUN) and Laser Lithotripsy for Renal Stones.

Objective: Sepsis is the most serious complication of flexible ureteroscopy (F-URS) and laser lithotripsy. We assessed the influence of positive stone culture (SC) on major infectious complications (sepsis, septic shock). Methods: This prospective study enrolled adult patients deemed suitable for F-URS and laser lithotripsy from nine centers (January 2022-August 2023). Inclusion criteria were as follows: kidney stone(s), preoperative midstream urine culture (MSUC), stone(s) assessed at computed tomography scan, and SC. Exclusion criteria were as follows: bilateral procedures, ureteral stones, and children. Group 1 included patients with sterile SC. Group 2 included patients with positive SC. Data are presented as median (interquartile range). A multivariable logistic regression analysis was performed to evaluate factors associated with having a positive SC. Results: In total, 293 patients were included. Median age was 51.0 (24) years. There were 167 (57.0%) males. Group 2 included 32 (2.5%) patients. Group 2 patients were significantly older [75.0 (14) vs 51.0 (23) years, p = 0.02]. Stone features were similar. Major infectious complications were higher in Group 2 (15.6% vs 0.4%). One patient died because of sepsis in Group 2. Two out of 6 (33.3%) patients with major infectious complications had the same pathogen in MSUC and SC. In the multivariable regression analysis, diabetes (OR 3.23), symptomatic urinary infections within 3 months before operation (OR 4.82) and preoperative stent/nephrostomy (OR 2.92) were factors significantly associated with higher odds of positive SC. Conclusions: Patients with positive SC have a higher incidence of major infectious complications after F-URS lithotripsy. SC should be performed whenever feasible because there is a poor correlation between MSUC and SC.

High-Power GHz Burst-Mode All-Fiber Laser System with Sub 300 fs Pulse Duration

An all-fiber low-repetition-rate SESAM mode-locked fiber oscillator combined with a dispersion-managed active fiber loop produces a flexible GHz burst-mode laser source. The high-power output is then produced by amplifying the GHz burst-mode laser source using an all-fiber chirped-pulse amplification system. Then, the laser is compressed using a grating pair compressor; a maximum amplified power of 97 W is obtained. This results in a compressed high power of 82.07 W with a power stability RMS of 0.09% and beam quality better than 1.2. Accurate dispersion control allows for the production of a high-quality pulse duration of 265 fs.

Flexible visible and near-infrared laser detector based on bismuth sulphide nanorods

The development of a flexible, visible and near-infrared laser detector with fast response holds significant potential for applications in wearable electronics, binary switches, and other fields. In this study, we utilized a flexible transparent polyimide (PI) substrate known for its exceptional thermal resistance up to 400 °C to fabricate an innovative type of flexible laser detector. Systematic investigations demonstrate that the bismuth sulphide nanorods-based laser detector exhibits not only high flexibility and light-weight properties but also excellent linear current characteristics and strong photosensitive dependence on laser light intensity. This research presents a novel approach for the fabrication of high-performance flexible optoelectronic devices.

Lasers in Gynecology.

The first published reports on the use of laser for cervical pathology date back to 1973. Technical advancements in flexible and rigid laser fibers revolutionized video laser laparoscopy in the 1990s. Fractionated lasers have been used to treat vulvovaginal symptoms associated with genitourinary syndrome of menopause, lichen sclerosus, and urinary incontinence. Review of available data suggests that fractionated lasers can improve both subjective and objective signs of vaginal atrophy and lichen sclerosus, but the evidence is weak because most of the trials are underpowered, are at risk for bias, and lack long-term follow-up. There is no strong evidence to support fractionated laser therapy for urinary incontinence or low-level laser therapy for chronic pelvic pain. Although short-term, single-arm trials suggest benefit of fractionated laser therapy for genitourinary syndrome of menopause, lichen sclerosus, and urinary incontinence, additional adequately powered, prospective, randomized, and longer-term comparative trials are needed before lasers can be recommended for these specific conditions. The purpose of this Clinical Expert Series is to review basic laser biophysics and the mechanism of action for modern fractionated lasers as relevant to the gynecologist. We also summarize safety and effectiveness data for lasers used for some of the most commonly studied gynecologic conditions: the vulvovaginal atrophy component of genitourinary syndrome of menopause, lichen sclerosus, and urinary incontinence.

Flexible laser plastic welding as an addition to AM

AbstractIndividualization, shorter product cycles and prototyping are leading to increased use of additive manufacturing in industry. A reliable and versatile process like laser plastic welding is needed to join parts with other additively manufactured or injection molded parts.

Flexible laser plastic welding as an addition to AM

Flexible laser plastic welding as an addition to AM

Design and optimization of a flexible fiber-conducted laser light guide plate system

As the demand for slim liquid crystal displays (LCDs) continues to rise in the lighting and visual display fields, the edge-lit backlight structure has received significant attention. However, the edge-lit backlight structure cannot function properly without a light guide plate (LGP) system. This study proposes a novel LGP system employing a laser as the light source and utilizing optical fiber as a waveguide. The design transmits a laser beam into the LGP through an optical fiber, adds microstructure and reflective surfaces, and optimizes the layout of the microstructure. Under the condition that a single point light source is used as the incident light source of the system, the illumination uniformity of the light output surface is finally realized to be as high as 95.8 %, and the light transmission efficiency is as high as 79.7 %. Next, the light output performance of the LGP was measured in the case of single-point light entry on the short side of the strip LGP, and the difference between the test results and the simulation data was within 5 %. The system adopts the fiber optic transmission method of electro-optical separation, which has certain application prospects in the fields of underwater detection, decorative lighting and urban landscape.

Multi-mode stable, high peak power Nd:YAG laser device for laser cleaning

High average power and peak power solid-state lasers are of great interest in the field of laser cleaning. In this research, a high peak power laser with over 400 W average power using a multi-mode stable resonator in a diode-pumped Nd:YAG master oscillator power amplifier has been demonstrated. A maximum peak power over 1.08 MW was achieved at a repetition frequency of 5 kHz. Delivery fiber with a 400 µm core diameter was utilized for flexible laser transmission. A prototype of the laser cleaning system was developed and inspiring application effects for paint and mold cleaning were achieved.

Assessing safety and efficacy of flexible ureteroscopy and laser lithotripsy in elderly patients

Assessing safety and efficacy of flexible ureteroscopy and laser lithotripsy in elderly patients