Advances In Laser Technology Research Articles

This Month in Adult Urology.

This Month in Adult Urology.

Freeform optics design method for illumination and laser beam shaping enabled by least squares and surface optimization

Freeform tailoring optics are core components in advanced illumination and laser technologies. In this work, we propose an efficient and streamlined optics design method to face the challenges in its implementation. We integrate ray-mapping least squares calculations with freeform surface optimization tools embedded in commercial optical design software. As a result, the complexity of freeform illumination and laser beam shaping design is significantly reduced by only adapting a built-in merit function. We demonstrate the feasibility of our approach through three design examples that provide tailored irradiance distributions. Furthermore, the results highlight the efficiency, simplicity and versatility of our approach that can be readily applied to multiple configurations.

Comparative study between thulium laser and cold knife visual urethrotomy for treatment of short bulbomembranous urethral stricture.

Introduction:The classical way to treat urethral stricture is the direct vision cold knife internal urethrotomy (DVIU). Along with advances in laser technology, laser urethrotomy is widely used, such as neodymium-doped yttrium aluminum garnet, argon, potassium titanyl phosphate, and thulium laser. We aimed to compare thulium laser urethrotomy (TLU) and cold knife visual urethrotomy (CKVU) in terms of short bulbomembranous urethral stricture management.Materials and methods:This prospective interventional study was conducted for 24 months, from January 2018 to January 2020, on 60 patients with primary short bulbo-membranous urethral stricture who came to the Department of Urology of Al-Azhar University Hospital, New Damietta, Egypt. We divided these patients into 2 age-matched groups; 30 patients treated with CKVU and 30 patients with TLU.Results:Regarding efficacy, postvoid residual urine volume (PVR) was reduced significantly in both groups (P < .001) after 6 months of follow-up; however, the reduction in TLU was greater than CKVU (P = .008). The improvement of Qmax after 6 months was significant and comparable in both groups. Regarding the quality of life, both groups showed a significant (<0.05) improvement in international prostate symptom score (IPSS) and the Male Sexual Health Questionnaire (MSHQ) scale, without no significant difference between both groups (>0.05). TLU showed a significantly (P = .038) shorter operative duration (24 ± 4.17 min) than CKVU duration (33 ± 4.86 min). Compared with CKVU, TLU was associated with less blood loss during surgery (P = .001), lower recurrence rate (46.7% vs. 19.97%, respectively), and lower frequencies of urethral dilatation (P = .001).Conclusion:TLU is an effective and safe therapy for managing bulbomembranous urethral strictures, with a relatively low recurrence rate. Further investigations of other techniques are recommended to look for the most appropriate procedure to combat the urethral stricture problem.

Light-responsive biomaterials for ocular drug delivery

Light-responsive biomaterials can be used for the delivery of therapeutic drugs and nucleic acids, where the tunable/precise delivery of payload highlights the potential of such biomaterials for treating a variety of conditions. The translucency of eyes and advances of laser technology in ophthalmology make light-responsive delivery of drugs feasible. Importantly, light can be applied in a non-invasive fashion; therefore, light-triggered drug delivery systems have great potential for clinical impact. This review will examine various types of light-responsive polymers and the chemistry that underpins their application as ophthalmic drug delivery systems.Graphical abstract

Investigation of the Interface between Laser-Melted CoCr and a Stainless Steel Substrate

Recent advances in laser technologies offer significant flexibility in the additive manufacturing domain. Extensive work was focused on material processing using laser-directed energy deposition for repairing parts. This pilot study investigated the use of selective laser melting (SLM) for depositing a superior material such as CoCr on an existing stainless steel base. The interface between these dissimilar materials was analyzed. During fabrication, both metals were gradually mixed in the liquid state as the first CoCr powder layer was melded on the steel base without obvious defects. According to SEM and EDAX, the heat-affected zone has a limited depth (&lt;20 µm). XRD patterns recorded across the CoCr–304 interface show a homogenous mixture of γ(Fe) and α(Co) solid solutions. The microporosity calculated by CT was under 0.5%. Microhardness was measured at and near the interface region, showing that the intermixing zone has high hardness (470–480 HV1), which may be related to the fine-grained microstructure. Mechanical testing reveals that the adhesion strength at rupture is 35% higher compared with the ultimate tensile strength of 304 steel. This adhesion strength can be attributed to the complete melting of CoCr particles after laser irradiation and to the reduced thickness of the HAZ and the IZ.

Microstructure and properties at bonds of diamond grains and Ni[sbnd]Cr filler alloy by fiber laser brazing

Advanced laser technology has been used in laser brazing to bond diamond grains in metal matrix to achieve some distinctive advantages such as high protrusion heights and large gaps of diamond grains. However, laser brazing has not been widely adopted as expected to produce various diamond tools since that bonding mechanisms, microstructures and characteristics of bonded interfaces have not fully investigated. In this paper, the experimental study was performed for using fiber laser brazing to bond diamond grains on steel substrate with NiCr filler alloy. Microstructures, graphitization, and shear force at the bonded interface were especially analyzed. The experiments led to the following outcomes: (1) the interface of diamond grains and NiCr alloy was a wavy surface with an average thickness of 7 μm. (2) Two types of carbide, i.e., Cr3C2 and Cr7C3, were generated on the brazed surface; Cr3C2 was lath-shaped and generated at first, and Cr7C3 was prismatic and built upon Cr3C2. (3) The interface of diamond grains and NiCr alloy was rough and accompanied by graphitization. (4) The shearing test showed that an average force of 138 N was applied to debone single diamond grain from filler metal.

Laser a Novel Method in the Management of Oral Soft Tissue Lesions

Light amplification by stimulated emission of radiation stands for LASER. The field of dentistry is revolutionised by the recent advances in laser technology. The excited atom stimulates emission of photons, which triggers the release of a subsequent photon is responsible for the generation of collimated, coherent, monochromatic beam of light or LASER. It is considered as light scalpel. Development in laser is tremendous with more specific for hard tissue and soft tissue treatments such as biopsy, photo biomodulation and photodynamic therapy by jus altering their wavelength. Treatment procedure of oral soft tissue lesion using laser with minimal pain and blood less field and ease of post operative healing is fortunate in the field of oral medicine and radiology to make these as chair side procedures. Keywords: Laser, oral mucosal lesions, Low level laser therapy, Photobiomodulation, Photodynamic therapy.

Quantification the diffusion-induced fractionation of 1H217O isotopologue in air accompanying the process of water evaporation

Advances in laser technology enabling simultaneous analyses of three heavy water isotopologues (1H2H16O, 1H218O and 1H217O) triggered renewed interest in studies of the hydrological cycle using full isotopic composition of water. Such studies require adequate knowledge of equilibrium and kinetic isotope effects accompanying phase transitions of water. Here we report the results of laboratory experiments aimed at quantification of diffusion-induced fractionation of 1H217O isotopologue in air, accompanying the process of water evaporation. Three evaporation experiments have been conducted: (i) evaporation under constant temperature and relative humidity levels, (ii) evaporation under constant temperature and at three different relative humidity levels, and (iii) evaporation under constant relative humidity level and at two different temperatures. Experiment (i) yield the value of diffusive fractionation coefficient of 1H217O isotopologue in air equal 14.64 ± 0.24‰ at 20.4 °C. This value is indistinguishable within the quoted uncertainties from the value of 14.71 ± 0.05‰ derived experimentally for the first time by Barkan and Luz (2007). We confronted these experimental values with the results of state-of-the art quantum–mechanical calculations published recently by Hellmann and Harvey (2020). Experiments (ii) and (iii) yield for the first time the experimental evidence that, contrary to the d-excess, the 17O-excess parameter is largely insensitive to changes in temperature but is sensitive to changes of the relative humidity and this sensitivity increases with the degree of isotope enrichment of the evaporating water body. The linear dependence of kinetic fractionation coefficients of heavy water isotopologues in air on the relative humidity deficit, postulated by the Craig-Gordon isotope model of evaporation process, was confirmed by the results of experiment (ii) for all three isotope systems studied, pointing to correctness of the conceptual framework underlying this widely used model.

A comparative study between Holmium Laser Enucleation of Prostate (HoLEP) and Transurethral resection of the prostate (TURP) in the treatment of benign prostatic hyperplasia

Background: Benign Prostatic Hyperplasia (BPH) is one of the most frequent diseases in men. The laser treatment for BPH has challenged TURP due to advances in laser technology, a better understanding of tissue-laser interactions, and rowing clinical experience.1 The objective of this work is to evaluate the safety and efficacy of Holmium Laser Enucleation of Prostate (HoLEP) and compare it to Bipolar Transurethral resection of the prostate (TURP). Methods: This is a prospective study to evaluate the outcomes in BPH patients undergoing surgery by HoLEP and Bipolar TURP done between January 2018 to December 2019. A total of 80 Patients were enrolled, forty undergoing HoLEP and the other forty went for Bipolar TURP for BPH. All patients with symptomatic BPH and who were candidates for surgical treatment were included. Patients with previous prostate surgery, urethral surgery, history of prostate cancer, or neurogenic bladder were excluded.1,2Results: Baseline parameters were almost similar between both groups in terms of age (years), International Prostatic Symptom Score (IPSS), Quality of life (QOL), Q max(ml/s), Post Void Residue (PVR), and gland size(grams) [Table 1]. Operative time and resected gland weight were more in HoLEP arm (p &lt; 0.001). Catheter time and Hospitalization period were significantly lower in the HoLEP group (p &lt; 0.0001). Haemoglobin drop was not significant between the two groups (p = 0.148). IPSS at three months was similar in both groups (p = 0.608). Qmax improved significantly in both groups, with 18.87 in TURP and 17.87 in HoLEP with a p-value of 0.261. PVR and QOL were similar between the two groups (P = 0.914 and P = 0.781) [Table 2]. Conclusion: Both Bipolar TURP and HoLEP were effective in relieving bladder outlet obstruction (BOO). HoLEP has equal efficacy compared to conventional bipolar TURP, with decreased hospital stay and catheter indwelling time.

Compact LWFA-Based Extreme Ultraviolet Free Electron Laser: Design Constraints

The combination of advanced high-power laser technology, new acceleration methods and achievements in undulator development offers the opportunity to build compact, high-brilliance free electron lasers driven by a laser wakefield accelerator. Here, we present a simulation study outlining the main requirements for the laser–plasma-based extreme ultraviolet free electron laser setup with the aim to reach saturation of the photon pulse energy in a single unit of a commercially available undulator with the deflection parameter K0 in the range of 1–1.5. A dedicated electron beam transport strategy that allows control of the electron beam slice parameters, including collective effects, required by the self-amplified spontaneous emission regime is proposed. Finally, a set of coherent photon radiation parameters achievable in the undulator section utilizing the best experimentally demonstrated electron beam parameters are analyzed. As a result, we demonstrate that the ultra-short, few-fs-level pulse of the photon radiation with the wavelength in the extreme ultraviolet range can be obtained with the peak brilliance of ∼7×1028 photons/pulse/mm2/mrad2/0.1%bw.

Comparative Efficacy of Laser Disinfection Versus Chemical Disinfection in Primary Root Canal – An In vitro Antimicrobial Study

Background: Conventional chemical root canal disinfection has been around for generations but it has its own drawbacks. Because of this there is a need for a better alternative for intracanal disinfection method. This alternative can be in the form of lasers, especially due to recent advances in laser technology. Methodology: The aim of the study is to compare chemical vs laser disinfection in primary root canal. This method has been tested in permanent teeth but not in primary teeth, this study was performed to evaluate the efficacy of laser disinfection compared to chemical disinfection. Results: The use of chemical disinfection by 5 ml of 5.25% NaOCl led to 96.7% microbial reduction against diode laser which achieved 97.7% reduction as compared to baseline microbial count and 34.4% reduction after irrigation using normal saline solution. Conclusion: Diode laser has similar root canal disinfection efficacy as compared to 5.25% NaOCl in primary canals. Diode lasers can be used as an alternative to chemical disinfection.

ELLIPTICALLY POLARIZED LASER-ASSISTED ELASTIC ELECTRONHYDROGEN ATOM COLLISION IN COULOMB POTENTIAL

The advancement of laser technology is causing the research field of optics to become more active, and with the help of advancementof technology, more detailed information can be obtained. The primary goal of this work is to calculate differential cross section by using a mathematical model in presence of coulomb potential and elliptically polarized beam with single photon absorption. The developed model shows the differential cross section increases with wavelength and decreases with electron energy with elliptically polarized beam. The differential cross section become maximum at 1.56 radian polarized angle and minimum at -1.56 radian polarized angle. The observation is based on 1.5eV laser photon energy, laser field intensity 1014Wcm−2 , polarized angle 1.56 radian angle, and electron energy 0 to 600eV. Using the born first approximation and the Volkov wave function, the developed equation is obtained. The numerically obtained differential crosssection in this work is approximately 10 −19𝑚2 to 10 −20𝑚2 , which is less than the differential cross section obtained by Flegel et al. (2013), which is approximately 10 −17𝑚2 .

Percutaneous laser nephrolithotripsy: is it here to stay? Results of a systematic review.

PCNL (percutaneous nephrolithotomy) and its miniaturized variants are being widely employed in stone surgery, owing to their high-stone-free rates (SFRs) and efficacy for large (>20 mm) stones. With advances in laser technology, it has been readily utilized in PCNL, with the potential for lower complication rates at similar SFR. We aimed to perform a systematic literature review with a focus on recent prospective clinical data that compares laser PCNL to either nonlaser PCNL, different PCNL sizes or other current standards of care such as shockwave lithotripsy (ESWL) or flexible ureteroscopy (FURS). Of the 294 studies initially identified through database searching, nine papers published between 2019 and 2021 were included which compared laser PCNL (Standard PCNL in three, mini-PCNL in four, ultra-mini PCNL in one, micro-PCNL in one study) to other nonlaser lithotripsy, ESWL, FURS, and different PCNL sizes. Complications for laser PCNL ranged from bleeding (4.4%), perirenal haematoma (1.1%), fever (4.6%), ureteric/renal pelvic injury (2.3%), haematuria (2.7%), and infection (2.6%). The mean SFR for laser PCNL was 91.5% at 3 months. Percutaneous laser nephrolithotripsy is well tolerated and effective, with high-SFRs at 3 months and relatively low intraoperative and postoperative complication rates. Further research is required to assess the role of intraoperative techniques and suction to improve outcomes further.

Ex Vivo Comparison of Efficiency, Safety, and Surgeon Satisfaction in Four Commercial Morcellators.

Introduction: Holmium laser enucleation of the prostate (HoLEP) is a size-independent treatment option for the management of benign prostatic hypertrophy. Although advancements in laser technology have led to clinical improvements in the enucleation portion of HoLEP, the morcellation aspect of HoLEP is often the rate-limiting step. We sought to compare efficiency and surgeon satisfaction in four commercial morcellators. Methods: This was an ex vivo study comparing four commercial morcellators: the Wolf Piranha™, the Lumenis VersaCut™, the JenaSurgical MultiCut Solo™, and the Hawk™ Morcellator. Four surgeons with significant experience performing HoLEPs participated. Surgeons tested each device to morcellate two different prostate models (1) morcellating as much microwave-cooked chicken breast in 10 minutes and (2) timed morcellation of bull testicles. Surgeons completed subjective surveys after each morcellator trial. Objective outcomes included the following: morcellation efficiency (g/min morcellated) and aspiration power (time to aspirate 1 L of saline). Means of continuous variables were compared using analysis of variance. Categorical variables were compared using chi-square tests. Statistical analyses were performed using SAS 9.4 (2019). Results: Comparing subjective outcomes, the Piranha™ was chosen as the safest morcellator (p = 0.0058). The least safe morcellator was thought to be the MultiCut by 75% of surgeons (p = 0.046). The Piranha™ was chosen as the most effective morcellator by 75% of surgeons (p = 0.046). Comparing objective parameters between the morcellators, the Piranha™ had the fastest aspiration time (43.50 ± 10.34 seconds, p = 0.0116). There were no significant differences in morcellation efficiency when using chicken breast (p = 0.3096). However, when comparing the morcellation efficiency using bull testicles, the Piranha™ had the highest efficiency at 39.68 ± 3.57 g/min (p = 0.0268). Conclusion: In this ex vivo study comparing four different commercially available morcellators, the Piranha™ had the highest aspiration power. No significant differences were found in morcellation efficiency using microwave-cooked chicken breast. The Piranha™ was felt to be the safest and most effective morcellator.

Near‐Surface Buried Plasmonic Nanoparticles in Glass as Novel Nonlinear Saturable Absorbers for Ultrafast Lasers

AbstractUltrafast lasers play important roles for scientific research and industrial applications. Saturable absorbers serve as crucial components for ultrafast laser generation. For decades, securing saturable absorbers with superior performance is one of the focuses in the field of advanced laser technology. In this work, the authors fabricate a new saturable absorption mirror (SAM) based on BK7 glass wafer, which is with a buried thin‐layer of silver (Ag) nanoparticles (NPs). The embedded Ag NPs‐based SAM (Ag‐NPs‐SAM) possesses excellent saturable absorption features due to the localized surface plasmon resonance (LSPR) effect of Ag NPs, and outstanding environmental stability owing to the protection of insulating dielectrics. In addition, benefiting from the ultrafast recovery time of Ag NPs, a continuous‐wave mode‐locking operation with the embedded Ag‐NPs‐SAM at 1037 nm is achieved in a Yb:KGW solid‐state laser system, obtaining pulses of a duration as short as 324 fs. The authors work offers a new strategy toward broadband response and high‐stability saturable absorbers for developing advanced ultrafast lasers.

Comparative appraisal with meta-analysis of erbium vs. CO2 lasers for atrophic acne scars.

Recent advances in laser technology allowed the development of systems that improve texture, appearance and pliability of skin in acne scars (AS). Currently, comprehensive comparative studies on the efficacy of the most commonly used fractional systems in AS are lacking. Thus, the aim of this work was to appraise and compare the clinical response to erbium versus CO2 lasers in AS in the form of a meta-analysis. The databases MEDLINE, EMBASE, Cochrane library were searched. Main clinical outcomes were investigator-reported scar improvement and participant-reported scar improvement. Five studies were included in this meta-analysis. Scar improvement was similar for both types of laser in terms of investigator-reported scar improvement (RR: 0.60 95% CI: 0.35-1.02) and participant-reported scar improvement (RR: 0.99 95% CI: 0.79-1.25). A sensitivity analysis that excluded studies with high risk of bias found the CO2 lasers to be superior to the erbium lasers (RR: 0.47 95% CI: 0.24-0.93): However, the subgroup analysis showed the CO2 laser not to be significantly different from either the non-ablative erbium (RR: 0.65 95% CI: 0.34-1.24) or the ablative erbium laser (RR: 0.60 95% CI: 0.35-1.02). The CO2 laser produced a slightly greater clinical response compared to the erbium lasers based on the physician's assessment. Overall, the two devices do not differ largely in terms of efficacy but may be complementary, with each resurfacing laser better suited for different clinical tasks.

Electrical Switching of Optical Gain in Perovskite Semiconductor Nanocrystals.

Perovskite semiconductor nanocrystals are promising for optical amplification and laser applications benefiting from efficient optical gain generation. Nevertheless, the pump threshold is limited by more than one exciton per nanocrystal required to generate population inversion in neutral nanocrystals due to the level degeneracy. Here, we show that by charging nanocrystals with current injection, the level degeneracy can be lifted to generate charged exciton gain with markedly low excitation density. On the basis of the scenario, we have demonstrated electrical switching of amplified spontaneous emission in films of CsPbBr3 nanocrystals sandwiched by two electrodes with over 50% threshold reduction owing to charged excitons. Our work provides an effective approach to electrically modulated optical gain in colloidal perovskite nanocrystals for potential applications in advanced laser and information technology.

Spatially resolved online particle detector using scintillators for laser-driven particle sources.

Laser-based particle accelerators have been an active field of research for over two decades moving from laser systems capable of one shot every hour to systems able to deliver repetition rates in the Hz regime. Based on the advancements in laser technology, the corresponding detection methods need to develop from single to multiple use with high readout speed. Here, we present an online compact trackerof particles using scintillators with nine resolvable energy levels and a spatial resolution of 3.6 × 3.6mm2 over the whole active area. This paper describes the designand construction of the detector, which is based on pixellated scintillators embedded inside an absorber matrix. The scintillator pixels are fiberoptically coupled to a camera system for online readout and analysis. Calibration with a radioactive source and first experimental data measuring laser accelerated ions at the PHELIX laser at GSI, Darmstadt, Germany, are presented and discussed.

Advanced Laser Technology for Quantum Communications (Tutorial Review)

AbstractQuantum communications is the art of exchanging and manipulating information beyond the capabilities of the conventional technologies using the laws of quantum mechanics. With applications ranging from quantum computing to cryptographic systems with information‐theoretic security, there is strong incentive to introduce quantum communications into many areas of the society. However, an important challenge is to develop viable technologies meeting the stringent requirements of low noise and high coherence for quantum state encoding, of high bit rate and low power for the integration with classical communication networks, and of scalable and low‐cost production for a practical wide‐deployment. This tutorial presents recent advances in laser modulation technologies that have enabled the development of efficient and versatile light sources for quantum communications, with a particular focus on quantum key distribution (QKD). Such approaches have been successfully used to demonstrate several QKD protocols with state‐of‐the‐art performance. The applications and experimental results are reviewed and interpreted in the light of a complete theoretical background, allowing the reader to model and simulate such sources.

Elastic electron-proton scattering in the presence of a circularly polarized laser field

Owing to recent advances in laser technology, it has become important to investigate fundamental laser-assisted processes in very powerful laser fields. In the present work and within the framework of laser-assisted quantum electrodynamics, electron-proton scattering was considered in the presence of a strong electromagnetic field of circular polarization. First, we present a study of the process where we only take into account the relativistic dressing of the electron without the proton. Then, in order to explore the effect of the proton dressing, we fully consider the relativistic dressing of the electron and the proton together and describe them by using Dirac–Volkov functions. The analytical expression for the differential cross section (DCS) in both cases is derived at lowest-order of perturbation theory. As a result, the DCS is notably reduced by the laser field. It is found that the effect of proton dressing begins to appear at laser field strengths greater than or equal to 1010 V cm−1 and it therefore must be taken into account. The influence of the laser field strength and frequency on the DCS is reported. A comparison with the Mott scattering and the laser-free results is also included.