Dual Laser System Research Articles

Dual-laser powder bed fusion using 450 nm diode area melting and 1064 nm galvo-scanning fiber laser sources

This study introduces an innovative dual laser powder bed fusion (PBF-LB/D) system, which combines two distinct laser processing methods to enhance control over microstructural outcomes. Unlike conventional PBF-LB systems that employ a single laser type, this dual-laser setup integrates a traversing Diode Area Melting (DAM) laser head with multiple 450 nm diode lasers (4 W each) and a traditional high-power (200 W) 1064 nm fiber-laser. This unique configuration allows for significantly different melt pool solidification rates within the same layer. For the first time, Ti6Al4V feedstock was processed using both laser types within a single sample. A specific scanning strategy defined separate laser processing regions, including an overlap where both lasers interacted to fuse the feedstock and bridge the two regions. The fiber-laser melted (FLM) regions experienced much higher cooling rates (∼107 °C/s) than the DAM regions (∼600 °C/s), resulting in acicular ά/α phases. In contrast, DAM regions exhibited larger grains, with parent β grain sizes approximately 13 times larger than those in the FLM zone. This dual laser system investigation not only demonstrates microstructural in-situ spatial tailoring but also highlights variations in the laser-induced heat-affected zone, surface roughness, and mechanical properties across different regions within the fabricated Ti6Al4V samples.

The impact of ring-shaped laser beam on dissimilar welding of Al-Cu thin sheets for battery tab-to-busbar connection: Microstructural, mechanical and electrical characteristics

Al-Cu dissimilar laser welding has gained substantial attention in the electric vehicle battery manufacturing, while challenged by the formation of brittle Al-Cu intermetallic compounds (IMCs). This study investigated the impact of beam shaping technology on the characteristics of Al-Cu dissimilar laser welds by using a coaxial core and ring dual beam laser system. The investigation assessed multi-level weld characteristics including weld geometry, IMC formation, mechanical and electrical properties. Results showed that the dual laser beam can effectively avoid imperfections observed with single beam, such as full penetration related to core-only beam and surface discontinuity defects associated with ring-only beam, respectively. For the core-only weld, extensive upward migration of Cu promoted the formation of brittle CuAl2 and Cu9Al4/Cu3Al2, leading to a considerable reduction in joint strength and a sharp increase in the electrical resistance. For the ring-only weld, the insufficient bonding area between Al and Cu sheet, leads to a significant degradation of joint strength, although a minimal electrical resistance was identified. An optimized power splitting was determined at 40% for the core beam and 60% for the ring beam, which allows the minimal formation of Al-Cu IMCs and consequently, the improved mechanical strength and reduced electrical resistance.

Resonant optical trapping of Janus nanoparticles in plasmonic nanoaperture

Controlled trapping of light-absorbing nanoparticles with low-power optical tweezers is crucial for remote manipulation of small objects. This study takes advantage of the synergetic effects of tightly confined local fields of plasmonic nanoaperture, self-induced back-action (SIBA) of nanoparticles, and resonant optical trapping method to demonstrate enhanced manipulation of Janus nanoparticles in metallic nanohole aperture. We theoretically demonstrate that displacement of Au-coated Janus nanoparticles toward plasmonic nanoaperture and proper orientation of the metal coating give rise to enhanced near-field intensity and pronounced optical force. We also explore the effect of resonant optical trapping by employing a dual-laser system, where an on-resonant green laser excites the metal-coated nanoparticle, whereas an off-resonant near-infrared laser plays trapping role. It is found that, at the optimum nanoparticle configuration, the resonant optical trapping technique can result in threefold enhancement of optical force, which is attributed to the excitation of surface plasmon resonance in Janus nanoparticles. The findings of this study might pave the way for low-power optical manipulation of light-absorbing nanoparticles with possible applications in nanorobotics and drug delivery.

Method to evaluate errors of Mie-Lidar in the transition zone with a dual CCD laser system

Mie Scattering Light Detection and Ranging (Mie-Lidar) is the most frequently used tool for obtaining the vertical profile of aerosol extinction coefficients. However, Mie-Lidar has an area that is not fully overlapping (called a transition zone) several hundred meters above the ground. There is uncertainty, although a geometric overlap factor (GOF) correction is normally used. To specifically evaluate the error of Mie-Lidar in the transition zone, a dual charge-coupled device (CCD) laser system (DCLS) is developed in this study. Multiple joint measurements as well as a continuous detection experiment are conducted. The extinction coefficient profiles obtained with the DCLS and Mie-Lidar are compared. The results indicate that the extinction coefficients are nearly consistent above the transition zone, and Pearson’s correlation coefficient remains above 0.9. However, the extinction coefficients have specific differences in the transition zone, and the linear fit results are relatively bad. The average relative difference of the extinction coefficients between the Mie-Lidar and DCLS is nearly 20%. Compared Mie-Lidar, the blind zone of the DCLS is merely approximately 8 m. The DCLS shows more details of the near-surface atmosphere, and its spatial resolution of up to 1 × 10–3 m can provide a useful reference for Mie-Lidar. The DCLS contributes to obtaining a more accurate vertical distribution of aerosols in the atmospheric boundary layer.

Fading Suppression for Distributed Acoustic Sensing Assisted With Dual-Laser System and Differential-Vector-Sum Algorithm

The sensing performance is severely affected by the intensity fading in the phase-sensitive optical time domain reflectometry ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\varphi $ </tex-math></inline-formula> -OTDR) based distributed acoustic sensing (DAS) system. The intensity fading manifests a stochastic amplitude fluctuation in the scattering signal. To suppress the fading noise, a heterodyne <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\varphi $ </tex-math></inline-formula> -OTDR system assisted with dual lasers with independent frequency, polarization, and initial phase is established to generate two pulses responses with different fading components at the same time. The backscattering signals from two individual probe pulses present different fading positions but possess the same phase change rate which is induced by the external disturbance. Through the differential-vector-sum algorithm including vectorization and phase differential, two complex Rayleigh backscattering beat signals from the two laser probes are efficiently synthesized, to simultaneously suppress the fading phenomenon caused by the inner pulse interference, polarization mismatch and phase mismatch. In the experimental validation, the probability of the fading channels in dual-laser scheme was significantly reduced from 9.4% to 1% compared with the single laser system, which is based on the resolution threshold of 2.1n <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\varepsilon / \surd $ </tex-math></inline-formula> Hz at 10Hz. Moreover, the dual-laser scheme also proves the polarization insensitivity by inducing a rapid polarization perturbation for two probe lasers. Owing to the fading noise suppression, the dynamic signal’s SNR of the dual-laser system was improved more than 20dB in the intensity fading channels, while the temporal and spatial resolution were not deteriorated. The proposed fading suppressed distributed sensing system possesses the excellent performance, which makes it play an important role for practical distributed acoustic sensing.

1,550 nm Erbium-Doped and 1,927 nm Thulium Nonablative Fractional Laser System: Best Practices and Treatment Setting Recommendations.

BACKGROUNDThe Fraxel Dual laser system (Solta Medical, Inc., Bothell, WA) contains a 1,550 and 1,927 nm wavelength single handpiece with different indications for each wavelength.OBJECTIVETo discuss treatment setting recommendations and best practices for select on-label and investigational applications of the 1,550 and 1,927 nm dual laser system.MATERIALS AND METHODSEight board-certified dermatologists with 10 or more years of experience with the 1,550 and 1,927 nm laser system completed an online survey about their clinical experience with the system and then participated in a roundtable to share clinical perspectives and best practices for using the laser system.RESULTSFor all Fitzpatrick skin types, treatment recommendations were described for selected approved indications for the 1,550 and 1,927 nm laser system, including both lasers in combination. Treatment recommendations were also reached for investigational applications with the 1,550 nm laser and 1,927 nm laser. Best practices for using the lasers during the treatment session to achieve optimal outcomes and decrease the post-treatment recovery time were compiled.CONCLUSIONThe 1,550 and 1,927 nm dual laser system is effective for a wide range of aesthetic and therapeutic applications, on and off the face and across all Fitzpatrick skin types.

Method to Evaluate the Errors of Mie-Lidar in the Transition Zone with a Dual Ccd Laser System

Method to Evaluate the Errors of Mie-Lidar in the Transition Zone with a Dual Ccd Laser System

Evaluation of miniaturized Raman spectrometers for planetary exploration: From aromatics to amino acids

Organic molecules are currently believed to be abundant in space, but the possible biogenic origin, or the mere existence, on some planetary surfaces, Mars specifically, is a pending question. Reliable methods of detection are required to answer this question unambiguously and Raman spectroscopy has already been suggested for this task years ago. With exploration missions aiming to Mars on the horizon, collecting experience and building databases will have crucial importance investigations of analytical data obtained through Raman instrumentation onboard of rovers in the frame of Mars 2020 and other forthcoming missions. This work focuses on the evaluation of some portable Raman systems coupled to different excitation lasers (532, 785, 1064 nm and a dual laser system with sequentially shifted excitation SSE) for the detection of various organic molecules, with emphasis on non-complicated measure protocol and observation of fluorescence emission when a different wavelength is used. By using a simple statistical approach, we demonstrate a generally good readability of the obtained spectra for most of the investigated organics regardless the excitation sources and instruments used. A varying level of fluorescence emission was encountered, resulting in higher background for the 532 nm and 785 nm instrumentation while 1064 nm and SSE spectrometers provided almost fluorescence-free spectra. These results illustrate how the relatively simple miniaturized Raman spectrometers can provide fast and unambiguous identification of various organic compounds which are of great importance in the current and future planetology and/or exobiology missions.

Comparison of a dual-laser and a Vis-NIR spectroscopy system for detection of chilling injury in kiwifruit

A novel dual-laser system with laser wavelengths of 730 nm and 850 nm has been developed for the non-destructive detection of chilling injury in Actinidia chinensis var. chinensis ‘Zesy002’ kiwifruit. Chilling injury in kiwifruit is a physiological disorder that may occur during low-temperature storage, with symptoms that are often not evident until the fruit is cut open. This study involved a sample of 162 kiwifruit with differing severity of chilling injury, and a performance comparison between the novel dual-laser system and a standard visible – near infrared (Vis-NIR) interactance spectroscopy approach proven in a prior study. The dual-laser system involved scanning the laser beams across the fruit to generate spatial profiles of light transmission in the fruit. Data analysis with supervised model training, using a support vector machine algorithm, was successfully used to achieve cross-validation prediction accuracies higher than 90 % for distinguishing sound and chilling-injured kiwifruit. The performance was equivalent to that achieved by the Vis-NIR interactance spectroscopy approach, suggesting that the dual-laser method is an alternative and more attractive option because of its easier system layout for high-speed on-line sorting of kiwifruit for chilling injury disorder.

Shaping 800 nm pulses of Yb/Tm co-doped laser: A control theoretic approach

Modern literature has demonstrated the use of fluorescent probes in optical microscopy. Most recently, Ytterbium (Yb3+) and Thulium (Tm3+) doped nanocrystals have been used to achieve the imaging of single upconversion nanoparticles in the Stimulated Emission Depletion (STED) microscope. However, precise control of the stimulated emission at 800 nm caused by the discharge of the metastable 3H4 energy level of the Tm3+ acceptor probe would provide enhanced imaging in modern microscopy by suppressing visible fluorescence emitted from the focal plane. In this interdisciplinary paper, Model-Free Control is combined with Sliding Control to shape 800 nm pulsed emission of the lanthanide co-doped dual-laser system. This is achieved by controlling the stimulated emission rate via automatic adjustment of the probing laser pump power. This new type of controller will not be impacted by model errors like its model-based counterparts and can be fabricated by complementary metal oxide semiconductor (CMOS) processes paving way to photonic integration. Numerical simulation of the controller is executed and shows that the error between desired pulsed emission and the system's output was below 0.0057%. Mathematical analysis of the control technique and the results obtained from numerical simulations are presented.

Study of nano particle stripping and composition inspection on wafer surface

Nano-scale particle stripping and inspection on silicon wafer are critical issues for Integrated Circuit(IC) manufacture industry. As more new materials are used in IC manufacture, not only particle itself but also its composition should be inspected. Particles are mainly adhered by the van der waals force. One of potential particle desorption method is laser cleaning which is environment friendly. However, the mechanism of laser cleaning is not clear and more studies should be done for laser ablation. In this paper, the kinetic process of nano particle on silicon wafer induced by nanosecond pulsed laser as well as the on-line detection method of particle composition were studied. A potential method of nano particle dynamic analysis and particle composition inspection were presented. A dual nanosecond pulse laser system both wavelengths at 532 nm is designed in which one laser pumps the particles away from wafer surface almost without damage, the other laser breakdowns the particles in air above the wafer surface to obtain the emission lines of the contaminated particles of 300 nm Cu by a spectroscopy with CCD. Particle motion trail in &lt;i&gt;z&lt;/i&gt; direction was observed after laser cleaning by analyzing particle spectral features. The particle dynamic model after stripping was established in which the resistance of air collision and gravity were included. And the model parameters were obtained by calculation using experimental results. The initial velocity of particle at the end of laser pulse and the average acceleration during laser interaction were calculated which were 7.6 m/s and 7.6 × 10&lt;sup&gt;8&lt;/sup&gt; m/s&lt;sup&gt;2&lt;/sup&gt; respectively. The sensitivity of the dual laser system was evaluated which was between 2.1 × 10&lt;sup&gt;13&lt;/sup&gt; to 5.1 × 10&lt;sup&gt;13&lt;/sup&gt; atoms/cm&lt;sup&gt;2&lt;/sup&gt;. As result, it is found that the gravity of the particle should not be ignored and the velocity divergence between different stripping particles is existed. The study not only provides a methodology for the study of laser-induced removal of nano particles on the wafer surface and laser induced nano particle dynamics, but also provides a potential method for the inspection of particle composition and pollution source monitoring on line in integrated circuit manufacture process. As the results were not the optimum one and further study should be done in which a better laser power density should be used.

Potential use of laser-induced breakdown spectroscopy combined laser cleaning for inspection of particle defect components on silicon wafer

The contamination control of silicon wafer surface is more and more strict. Many investigations have been done to inspect defects on silicon wafer. However, rare studies have been reported on defect component inspection, which is also critical to trace the source of defects and monitor manufacturing processes in time. In order to inspect the components of contaminated particles on silicon wafer, especially with a high-speed, in-line mode and negligible damage, a dual nanosecond pulse laser system with both wavelengths at 532 nm is designed, in which one laser pumps the particles away from the wafer surface with negligible damage, the other laser breaks down the particles in the air above the wafer surface to obtain the emission lines of the contaminated particles by a spectroscopy with intensified charge coupled device. The sensitivity of the dual pulse laser system is evaluated. The particle dynamic process after pump is analyzed. The results in this work provide a potential on-line method for the semiconductor industry to trace the sources of defects during the manufacture process.

Impact of build envelope on the properties of additive manufactured parts from AlSi10Mg

The selective laser melting (SLM) process is well established in the construction of prototypes and in the low volume production. With increasing build-up rates the next step to serial production is possible. Multi laser systems and larger build envelopes make the process cost-efficient. Enlarged systems enable not only the manufacturing of numerous smaller parts in one build job but also bigger parts for the automotive and aerospace industry. A modified metal laser melting machine X LINE 2000R equipped with a dual laser system and an enlarged build envelope is used to investigate the position-dependent properties of parts made from AlSi10Mg. The impact on porosity and mechanical properties is shown for different spatial directions. The results are an important contribution to process design, component layout and further improvements of larger SLM machines.

Reconfigurable photonic generation of broadband chirped waveforms using a single CW laser and low-frequency electronics

Broadband radio-frequency chirped waveforms (RFCWs) with dynamically tunable parameters are of fundamental interest to many practical applications. Recently, photonic-assisted solutions have been demonstrated to overcome the bandwidth and flexibility constraints of electronic RFCW generation techniques. However, state-of-the-art photonic techniques involve broadband mode-locked lasers, complex dual laser systems, or fast electronics, increasing significantly the complexity and cost of the resulting platforms. Here we demonstrate a novel concept for photonic generation of broadband RFCWs using a simple architecture, involving a single CW laser, a recirculating frequency-shifting loop, and standard low-frequency electronics. All the chirp waveform parameters, namely sign and value of the chirp rate, central frequency and bandwidth, duration and repetition rate, are easily reconfigurable. We report the generation of mutually coherent RF chirps, with bandwidth above 28 GHz, and time-bandwidth product exceeding 1000, limited by the available detection bandwidth. The capabilities of this simple platform fulfill the stringent requirements for real-world applications.

The efficiency of using dual laser system zero in off clamp nephron-sparing surgery

Objective To evaluate the efficacy of using dual laser system in off clamp nephron-sparing surgery. Methods We used dual laser system in the patients who underwent off-clamp NSS between Jan 2016 and Apr 2016 in our institution. There were 16 males and 8 females with average age of 49 years. Mean tumor size was 1.9 cm (range 0.8-3.2 cm). The mean R. E.N.A.L. score was 3.8(range 3-6). The mean Zhongshan score was 3.5(range 3-5). The mean ZII(zero ischemia index)was 1.6(range 1-4). The Evolve Dual (980 nm/1 470 nm) laser system set at 60 W in continuous mode was used. Results Off-clamp NSS was successfully performed in 22 patients except for renal artery occlusion in 2 case. Mean operative time was 74 min(range 50-100 min); The average estimated blood loss was 52.9 ml(range 10-200 ml); Mean postoperative drainage was 65.4 ml(range 20-150ml); Mean postoperative hospital stay was 5.2 days (range: 4-7days). No severe post-operative complication was found. The mean pre- and postoperative serum creatinine levels were 76.2 μmol/L(range: 48-112μmol/L) and 81.5μmol/L(range: 54-122 μmol/L) with no significant difference(P>0.05). The postoperative pathology indicated that 20 cases of clear cell carcinomas, 3 cases of chromophobe renal cell carcinomas, one case of papillary carcinoma. Conclusions Dual laser system can be used in off clamp nephron-sparing surgery safely and effectively. Key words: Nephron sparing surgery; Off-clamp; Renal neoplasm; Dual laser system

Development of an HCN dual laser for the interferometer on EAST**Contributed paper, published as part of the Proceedings of the 3rd Domestic Electromagnetic Plasma Diagnostics Workshop, September 2016, Hefei, China.

A two-color continuous wave (CW) discharge-pumped far-infrared (FIR) hydrogen cyanide (HCN) laser was developed as the source of an interferometer for measuring the line-averaged electron density in the Experimental Advanced Superconducting Tokamak (EAST). The output power of the dual laser system was about 120 mW from each laser on the 337 μm (0.89 THz) line. The polarization of each output beam was fixed using thin tungsten filaments and oscillated in the EH11 mode. Different megahertz intermediate frequencies (IF) and a slight frequency offset (∼1 MHz) were generated in this system to replace the traditional rotating grating with ∼10 kHz IF, and this can improve the time resolution of the interferometer significantly. The experimental result showed that different IF signals were obtained by successfully adjusting the cavity length. In particular, the beat frequency was captured at ∼1.3 MHz by a Schottky mixer when the length of the resonant cavities was changed by 5 μm by an automatic adjustment system. In order to study the character of IF, a long time record of the IF signal was carried out, and the IF signal could be stabilized for a few minutes in the range of 2 MHz to 3 MHz. A real-time IF stability control system was initially designed for long pulse discharge experiments on the EAST. The ∼MHz frequency response and good phase sensitivity of the dual laser HCN interferometer will allow the system to track fast density profiles and resolve fast MHD events, such as tearing/neoclassical tearing, disruptions, etc.

Feasibility of hysteroscopic endometrial polypectomy using a new dual wavelengths laser system (DWLS): preliminary results of a pilot study.

Currently, endometrial polyps may be successfully treated in an outpatient setting with 5 Fr mechanical and bipolar instruments. Our aim is to evaluate the benefits of minimally invasive techniques in hysteroscopy, focusing on the use of a new dual wavelengths laser system in the treatment of endometrial polyps in an outpatient setting. Between September 2012 and December 2014, all consecutive patients of reproductive and menopausal age with ultrasound diagnosis of endometrial polyp with maximum diameter ≤2.5cm were eligible to participate in a prospective study. They underwent a hysteroscopic procedure with excision of the polyp using a new dual wavelengths laser system. All procedures were performed on an outpatient basis without anesthesia. Laser polypectomy was successfully performed in 219 out of 225 (97.3%). Success of surgery was not influenced by the initial location of polyp. No main complications were reported during or immediately after the procedure. 6 and 12months follow-up with ultrasound scan did not show any persistence or recurrence of the pathology. Our preliminary findings seem to support the safety and the effectiveness of the laser hysteroscopic endometrial polypectomy. However, further studies are mandatory to validate its use in daily hysteroscopic practice.

Development of high throughput Dual Laser system incorporating CCD-based multichannel Czerny – Turner spectrometer for real-time qPCR fluorescence intensity measurements

In this article, the development of a commercial high throughput system incorporating a multichannel CCD-based Czerny – Turner spectrometer for real-time fluorescence quantitative polymerase chain reaction (qPCR) measurements is described. The system employs two 20 mW lasers (532 ± 1 nm and 637 ± 3 nm) 2.5× Galilean beam expander-focuser, 5×4-200 μm core diameter fiber-optic bundle and a two-axis galvanometer for exciting fluorescent dyes. Further, the optical measurement system can detect twenty reaction vessels in asynchronous manner and up to five different fluorescent dyes (5-plex) at 1 nM dye concentration in each of the reaction vessels simultaneously. Moreover, PCR curves obtained using the optical measurement system for a genomic deoxyribonucleic acid (DNA) template containing three fluorescent generic binding dyes (FAM, Q670 and CRF610) is discussed. The measurement system repeatability is <1% CV (coefficient of variance). Finally, a performance comparison between the reported qPCR laser-based measurement system and an LED-based qPCR measurement system described by the author in ref. 14 is provided.

Anti-Mullerian hormone trend evaluation after laparoscopic surgery of monolateral endometrioma using a new dual wavelengths laser system (DWLS) for hemostasis

Operative laparoscopy is the gold standard in the treatment of endometriotic ovarian cysts. Excisional surgery is the best technique to prevent recurrences and improve symptoms but it may result in ovarian reserve damage due to the removal of healthy ovarian cortex. The aim of this study was to assess the impact on ovarian reserve of the use of dual wavelengths laser system (DWLS) hemostasis after stripping technique of monolateral endometrioma, by dosing the anti-Mullerian hormone (AMH). This prospective study was conducted at the Institute of Obstetrics and Gynecology, University of Foggia, from December 2013 to January 2015. Forty-five women underwent excision of monolateral endometriotic ovarian cyst by stripping without using a bipolar coagulation and performing hemostasis with a DWLS. The AMH serum levels were estimated before the surgery (T0), 4–6 weeks (T1) and 6–9 months (T2) after surgery. Our results suggest that an appropriate surgical technique with the use of laser hemostasis does not determine a significant reduction of ovarian reserve. Laser hemostasis could prevent follicular reserve loss after ovarian endometrioma surgery.

Dual-Sweep Frequency Scanning Interferometry Using Four Wave Mixing

Frequency scanning interferometry is a well-known technique to measure the distance to a reflecting target. However, variations in the optical path length during the finite measurement time severely limit the applicability of the method in real-world environments. By the use of a second swept source measurements become immune to these variations. The use of a second source implies a great increase in costs and complexity. In this letter, we explore the possibility of using four wave mixing for the generation of the secondary swept frequency source. This greatly reduces the increase in costs and solves the synchronization issues often encountered by dual laser systems. A prototype has been built and tested against induced variations in the optical path length, proving the ability of the technique to improve distance measurements in industrial environments.