A Pilot Split-Neck Case Study to Compare the Efficacy of the Long-Pulsed 755 nm Laser and the 532 nm Picosecond Laser for Acrochordon Removal

박종헌,정재영,류화정,김일환 대한피부과학회 2023 Annals of Dermatology Vol.35 No.-

Cutaneous papillomas or acrochorda usually appear after the 4th decade of life in areas with skin folds. Conventional methods of removal are associated with bleeding problems, pain and prolonged sequelae. Thus, acrochorda removal with lasers has gained attention. In this study, we compared the efficacy of two popular laser types with different wavelengths and pulse widths for removal of skin tags. A 60-year-old Korean male noticed skin tags on his neck bilaterally. All tags were treated in a single session, on one side with a picosecond (ps)- domain 532 nm Nd:YAG laser and on the contralateral side with a long-pulsed (LP) 755 nm alexandrite laser. The endpoint for the ps-532 laser was immediate whitening, while that for the LP and quasi-LP (QLP) 755 lasers were visible changes on the surface of the lesion. An- tibiotic ointment was applied, dressing was done and clinical photographs were taken. Both lasers effectively removed the skin tags at all settings in a single session without bleeding and with minimal discomfort. Crust formation occurred on both sides with natural shed- ding within 1 to 2 weeks. Transient erythema lasted longer in the tags treated with the ps- 532 laser. At the 5th month of follow-up, residual lesions were detected on the field treated with the ps-532 laser. No persistent side effects such as scarring or postinf lammatory hy- perpigmentation (PIH) were observed. In conclusion, both the ps-532 nm Nd:YAG and the 755 nm alexandrite lasers ensured safe and effective removal of skin tags in a single session without adverse sequelae. Key words: Alexandrite laser, Fibro

Pilot study on efficacy and patient satisfaction with 1,450-nm laser boosting treatment after a thread lift procedure

Chang Hosun,Kang Kyoungjin 대한미용의학회 2022 대한미용의학회지 Vol.6 No.1

Background: Polydioxanone used in thread lifting is mostly absorbed in skin tissues within six months, and its therapeutic effect diminishes gradually. However, we often experience a decrease in the effectiveness of thread lifting within 1–2 months. We performed a laser boosting treatment to maintain the long-term effect of thread lifting and reported its additional utility. Objective: To investigated the impact of laser boosting treatment on therapeutic effect and patient satisfaction after thread lifting during the first three months. Methods: This study was conducted between March and July, 2019. Severity of jawline and mouth corner sagging were graded by Merz Scale scores in seven middle-aged female patients. After the symmetrical thread lift procedure, 1,450-nm laser boosting treatment was applied to the side of the face with higher preoperative grade. Average pain scores at postoperative day (POD) 0, 3, and 7 were compared, including changes from POD 0 to POD 3 and 7. Face halves were compared regarding improvements in elasticity, skin tone, sagging of mouth corners, jawline sagging, overall satisfaction, and Merz Scale scores after three months. Results: All the patients showed improvements in elasticity, skin tone, sagging of mouth corners, and jawline sagging with improved overall patient satisfaction. During pain assessment, five of the seven patients showed greater changes in the laser-treated side at POD 3 and 7. Comparing the Merz Scale scores, there was a significant difference between pre-and post-treatment in jawline sagging and between jawline sagging and sagging of mouth corner in the laser-treated side. Conclusion: A 1,450‑nm laser boosting treatment can help reduce pain and discomfort during early stages after thread lifting and improve elasticity, skin tone, sagging of mouth corners, jawline sagging, and overall patient satisfaction. Laser boosting treatment should be actively considered during thread lift to improve sagging of the mouth corner and jawline. Background: Polydioxanone used in thread lifting is mostly absorbed in skin tissues within six months, and its therapeutic effect diminishes gradually. However, we often experience a decrease in the effectiveness of thread lifting within 1–2 months. We performed a laser boosting treatment to maintain the long-term effect of thread lifting and reported its additional utility. Objective: To investigated the impact of laser boosting treatment on therapeutic effect and patient satisfaction after thread lifting during the first three months. Methods: This study was conducted between March and July, 2019. Severity of jawline and mouth corner sagging were graded by Merz Scale scores in seven middle-aged female patients. After the symmetrical thread lift procedure, 1,450-nm laser boosting treatment was applied to the side of the face with higher preoperative grade. Average pain scores at postoperative day (POD) 0, 3, and 7 were compared, including changes from POD 0 to POD 3 and 7. Face halves were compared regarding improvements in elasticity, skin tone, sagging of mouth corners, jawline sagging, overall satisfaction, and Merz Scale scores after three months. Results: All the patients showed improvements in elasticity, skin tone, sagging of mouth corners, and jawline sagging with improved overall patient satisfaction. During pain assessment, five of the seven patients showed greater changes in the laser-treated side at POD 3 and 7. Comparing the Merz Scale scores, there was a significant difference between pre- and post-treatment in jawline sagging and between jawline sagging and sagging of mouth corner in the laser-treated side. Conclusion: A 1,450‑nm laser boosting treatment can help reduce pain and discomfort during early stages after thread lifting and improve elasticity, skin tone, sagging of mouth corners, jawline sagging, and overall patient satisfaction. Laser boosting treatment should be actively considered during thread lift to improve sagging of the mouth corner and jawline.

Review of picosecond lasers in non-pigmented disorders

Jun Ki Hong,Joon Seok,최선영,이갑석,김범준,유광호 대한의학레이저학회 2022 MEDICAL LASERS Vol.11 No.3

Based on the principles of the selective photothermolysis theory, pico-second lasers can enhance the therapeutic effect on the target tissue and minimize damage to the surrounding tissue. Therefore, picosecond lasers have significant advantages over conventional laser techniques in terms of effectiveness, safety, and therapeutic effect on the pigmented skin. Additionally, picosecond lasers induce intraepidermal and dermal vacuole formation through laser-induced optical breakdown, which is associated with dermal remodeling by increasing dermal collagen and elastin formation. Based on these additional findings, picosecond lasers are reportedly effective in treating non-pigmented disorders, scars, and in cutaneous rejuvenation. Herein, we review the literature on the treatment of non-pigmented disorders by a picosecond laser and confirm its efficacy.

Exploration of Strong Field Physics with Multi-PW Lasers

이성구,김형택,최일우,김철민,남창희 한국물리학회 2018 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.73 No.2

At the Center for Relativistic Laser Science (CoReLS) petawatt (PW) lasers have been developed for the investigations of strong field physics. The CoReLS has successfully upgraded one of the existing PW laser beamlines to a 4 PW laser at 20 fs. From laser-driven charged-particle acceleration experiments, multi-GeV electrons and 90-MeV protons can be generated using the laser wakefield acceleration and the radiation pressure acceleration schemes, respectively. The GeV electron beam can be, in turn, used for Compton backscattering with another PW laser. Such a Compton scattering process can be examined for other quantum electrodynamics (QED) effects, including the radiation reaction effect and the Breit-Wheeler pair production process. PW lasers have, thus, offered new opportunities to pursue novel physics research in relativistic plasma physics, strong field quantum electrodynamics, nuclear physics and laboratory astrophysics.

High-power fiber laser cutting parameter optimization for nuclear Decommissioning

Ana Beatriz Lopez,Eurico Assunç~ao,Luisa Quintino,Jonathan Blackburn,Ali Khan 한국원자력학회 2017 Nuclear Engineering and Technology Vol.49 No.4

For more than 10 years, the laser process has been studied for dismantling work; however, relatively fewresearch works have addressed the effect of high-power fiber laser cutting for thick sections. Since in thenuclear sector, a significant quantity of thick material is required to be cut, this study aims to improve thereliability of laser cutting for such work and indicates guidelines to optimize the cutting procedure, inparticular, nozzle combinations (standoff distance and focus position), to minimize waste material. Theresults obtained show the performance levels that can be reached with 10 kW fiber lasers, using which itis possible to obtain narrower kerfs than those found in published results obtained with other lasers. Nonetheless, fiber lasers appear to show the same effects as those of CO2 and ND:YAG lasers. Thus, themain factor that affects the kerf width is the focal position, which means that minimum laser spot diametersare advised for smaller kerf widths.

전립선 레이저치료의 최신지견

서덕하,감성철 대한의사협회 2017 대한의사협회지 Vol.60 No.5

Benign prostatic hyperplasia (BPH) is one of the most common urological diseases in men after middle age. The most common surgical treatment of BPH is transurethral prostatectomy. Recently, because of the rapid development of lasers, they have been used for the treatment of BPH. The treatment of BPH using lasers has been shown to lead to significant improvements in symptoms and to have excellent therapeutic effects. It is widely used as a minimally invasive treatment of BPH because of the risk and complications associated with transurethral prostate resection. Currently, 3 kinds of lasers are generally used in the treatment of BPH in Korea: potassium-titanyl-phosphate, holmium, and thulium lasers. With developments in laser technology, surgical procedures have improved continuously. The most common surgical procedures are holmium laser enucleation of the prostate (HoLEP), photoselective vaporization of the prostate (PVP), and thulium laser enucleation of the prostate. HoLEP is an effective surgical procedure for large prostates. PVP is safe for patients who are elderly, are in poor general health, or are taking anticoagulants. Thulium laser enucleation of prostate has advantages over PVP and HoLEP surgery due to specific characteristics of the laser and the surgical method. Compared with transurethral prostate resection, laser-based surgical procedures require shorter hospitalization and Foley catheter insertion periods. HoLEP and PVP are safe and effective methods for the surgical treatment of BPH. Therefore, if more data are accumulated from research into these methods, they will become the standard surgical treatments for prostate hyperplasia.

문턱 전류 이상에서 Complex-Coupled DFB 레이저 다이오드의 여러 가지 결합 계수 비와 양 단면 반사율 조합에 따른 단일 모드 수율 해석

김부균,김상택,전재두 한국광학회 2003 한국광학회지 Vol.14 No.5

For complex-coupled (CC) DFB lasers, we found that there might be little correlation between the single mode yields at threshold and above threshold. At threshold, the single mode yield considering f number of in-phase (IP) CC DFB lasers is the same as that of anti-phase (AP) CC DFB lasers. However, the single mode yield as a function of injection current above threshold of IP CC DFB lasers is much different from that of AP CC DFB lasers. In the case of IP CC DFB lasers, the single mode yield increases as the coupling coefficient ratio (CR) increases, while, in the case of AP CC DFB lasers, the single mode yield decreases rapidly regardless of CR as the injection current increases. In the case of AR-HR combinations, the effect of AR ref1ectivity on the single mode yield increases as the coupling strength decreases. As the coupling strength decreases, the CR at which the increase rate of the single mode yield starts to decrease, increases, and the maximum single mode yield increases. Single mode yields of AR-HR and AR-AR combinations are larger than those of AR-CL and CL-CL combinations. Complex-coupled(CC) DFB 레이저의 경우 문턱 전류에서 spatial hole burning (SHB)현상을 나타내는 f 계수를 고려하여 구한 단일 모드 수율과 문턱 전류 이상에서의 단일 모드 수율과의 연관성이 존재하지 않음을 알 수 있었다. 문턱 전류에서 f 계수를 고려하여 구한 in-phase (IP) CC DFB 레이저와 anti-phase (AP) CC DFB 레이저의 단일 모드 수율은 일치하였으나 문턱 전류 이상에서는 큰 차이를 보였다. 문턱 전류 이상에서 IP CC DFB 레이저의 단일 모드 수율은 결합 계수 비가 증가할수록 증가하였다 반면에 AP CC DFB 레이저의 경우 결합 계수 비에 관계없이 주입 전류가 증가하면 단일 모드 수율은 급격히 감소함을 알 수 있었다. 양 단면 반사율 조합이 AR-HR인 경우 결합 세기가 작을수록 AR 단면의 반사율이 단일 모드 수율에 미치는 영향이 크게 나타났다. 결합 세기가 작을수록 단일 모드 수율의 증가율이 완만해지기 시작하는 결합 계수 비가 커졌고 또한 최대 단일 모드 수율이 증가하였다 양 단면 반사율 조합이 AR-HR과 AR-AR의 경우가 AR-CL과 CL-CL인 경우에 비하여 단일 모드 수율이 크게 나타났다.

Laser Microfabrication for Silicon Restrictor

Kim, Kwang-Ryul,Jeong, Young-Keun The Korean Powder Metallurgy Institute 2008 한국분말재료학회지 (KPMI) Vol.15 No.1

The restrictor, which is a fluid channel from a reservoir to a chamber inside a thermal micro actuator, has been fabricated using ArF and KrF excimer lasers, Diode-Pumped Solid State Lasers (DPSSL) and femtosecond lasers for a feasibility study. A numerical model of fluid dynamics for the actuator chamber and restrictor is presented. The model includes bubble formation and growth, droplet ejection through nozzle, and dynamics of fluid refill through the restrictor from a reservoir. Since an optimized and well-fabricated restrictor is important for a high frequency actuator, some special beam delivery setups and post processing techniques have been researched and developed. The effects of variations of the restrictor length, diameter, and tapered shapes are simulated and the results are analyzed to determine the optimal design. The numerical results of droplet velocity and volume are compared with the experimental results of a cylindrical-shaped actuator. It is found that the micro actuators having tapered restrictors show better high frequency characteristics than those having a cylindrical shape without any notable decrease of droplet volume. The laser-fabricated restrictors demonstrate initial feasibility for the laser direct ablation technique although more development is required.

Characteristics of a Laser Beam Produced by Using Thermal Lensing Effect Compensation in a Fiber-coupled Laser-diode-pumped Nd:YAG Ceramic Laser

김덕래,김병태 한국물리학회 2010 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.57 No.2

The characteristics of a laser beam produced by using thermal lensing effect compensation in a fiber-coupled laser-diode Nd:YAG ceramic laser were investigated. The thermal lensing effect was compensated for by using a compensator, which was 25 mm away from the laser rod, with a focal length of 30 mm and an effective clear aperture of 22 mm. Using a compensator, the divergence and the beam propagation factor M2 of the output beam were 5.5 mrad and 2.4, respectively, under a pump power of 12W. The high-frequency components in the compensated laser beam were removed.

RESEARCH ON LASER-ACCELERATED PROTON GENERATION AT KAERI

PARK SEONG HEE,LEE KITAE,CHA YOUNG HO,JEONG YOUNG UK,BAIK SUNG HOON,YOO BYUNG DUK Korean Nuclear Society 2005 Nuclear Engineering and Technology Vol.37 No.3

A prototype of a relativistic proton generation system, based on laser-induced plasma interaction, has been designed and fabricated. The system is composed of three major parts: a fs TW laser; a target chamber, including targets and controls; and a diagnostic system for charged particles and lasers. An Offner-type pulse stretcher for chirped pulse amplification (CPA) and eight pass pre-amplifier are installed. The main amplifier will be integrated with a new pumping laser. The design values of the laser at the first stage are 1 TW in power and 50 fs in pulse duration. We expect to generate protons with their maximum energy of approximately 3 MeV and the flux of at least $10^6$ per pulse using a 10 $\mu$m Al target. A prototype target chamber with eight 8-inch flanges, including target mounts, has been designed and fabricated. For laser diagnostics, an adaptive optics based on the Shack-Hartmann type, beam monitoring, and alignment system are all under development. For a charged particle, CR-39 detectors, a Thomson parabola spectrometer, and Si charged-particle detectors will be used for the density profile and energy spectrum. In this paper, we present the preliminary design for laser-induced proton generation. We also present plans for future work, as well as theoretical simulations.