• Medical Lasers
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• v.9 no.2
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• pp.110-118
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• 2020

The non-ablative fractional dual laser is equipped with two types of lasers, 1550 nm and 1927 nm in one device, and was approved by the United States Food and Drug Administration in 2013. The advantages of the non-ablative fractional laser (NAFL) include fewer side effects such as erythema, edema, post-laser pigmentation, and scab formation. Thus, the NAFL is preferred by both practitioners and consumers because it is convenient and safe for use. The 1550 nm erbium glass and 1927 nm thulium lasers are representative NAFLs that have been developed separately and are often used as a single-wavelength laser with proven clinical efficacy in various indications. The 1550 nm wavelength laser penetrates the dermis layer and the 1927 nm wavelength laser is effective for epidermal lesions. Therefore, targeting the skin layer can be easily achieved with both the 1550 and 1927 nm lasers, respectively, or in combination. Clinically, the 1550 nm laser is effective in the treatment of mild to moderate sagging and wrinkles, scars, and resurfacing. The 1927 nm laser improves skin texture and treats skin pigmentation and wounds. It can also be used for drug delivery. The selection and utilization rate of NAFL has been increasing in recent times, due to changes in lifestyle patterns and the need for beauty treatments with fewer side effects and short downtime. In this study, we present a plan for safe and effective laser therapy through a review of literature. Clinical applications of the multifunctional NAFL are also described.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2006.05a
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• pp.663-664
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• 2006

In the electronic, medical, aerospace and automobile industries, many products and parts are manufactured by joining. Recently, as these get smaller, micro joining is becoming more and more important. In this study, micro wire-to-micro wire parallel joining was performed using single mode fiber laser. Maximum power of the fiber laser is 100 W. The CCD(Charge- Coupled Device, CCD) camera to observe the specimen was made up. The objective was applied to micro joining system to make a small spot size of laser beam. In order to control the target position, micro-multi-axis-stage was set up. This paper presents results for the single mode fiber laser joining of micro wires.

• Journal of Biomedical Engineering Research
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• v.10 no.2
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• pp.94-96
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• 1989

Explosive evaporative removal process of biological tissue by absorption of a CW laser has been simulated by using gelatin and a multimode Nd:YAG laser. Because the point of maximun temperature of laser-irradiated gelatin exists below the surface due to surface cooling, evaporation at the boiling temperature is made explosively from below the surface. The important parameters of this process are the conduction loss to laser power absorption (defined as the conduction-to-laser power parameter, Nk), the convection heat transfer at the surface to conduction loss (defined as Bi), dimensionless extinction coefficient (defined as Br.), and dimensionless irradiation time (defined as Fo). Dependence of Fo on Nk and Bi has been observed by experiment, and the results have been compared with the numerical results obtained by solving a 2-dimensional conduction equation. Fo and explosion depth (from the surface to the point of maximun temperature) are increased when Nk and Bi are increased.To find out the minimum laser power for explosive evaporative removal process, steady state analysis has been also made. The limit of Nk to induce evaporative removal, which is proportional to the inverse of the laser power, has been obtained.

• Medical Lasers
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• v.9 no.1
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• pp.76-78
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• 2020

Verruca plana is a cutaneous infection caused by the human papilloma virus. Although various treatment methods are currently available, most have limitations due to the risk of complications such as hyperpigmentation, edema, and scarring. Moreover, as the infection tends to spread easily, new verrucae can potentially develop, and treatment procedure times tend to be lengthy. Thus, novel treatment methods are required. The 2790-nm wavelength erbium:yttrium-scandium-gallium-garnet (Er:YSGG) laser is a superficial resurfacing laser. Here, we present a case of a 25-year-old woman with multiple verrucae treated using a 2790-nm Er:YSGG laser. Compared to traditional methods, this novel laser is convenient, produces better cosmetic outcomes, and is less time-consuming; it is therefore suitable for the treatment of facial verruca plana.

• Medical Lasers
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• v.9 no.2
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• pp.179-183
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• 2020

The picosecond laser has been widely used to remove tattoos, and improve wrinkles, acne scarring, and pigmented scars. This study was performed to investigate the efficacy and safety of a 1,064-nm fractional picosecond laser treatment for depressed traumatic scars. A total of twenty Korean patients with depressed scars were treated with a 1,064-nm fractional picosecond laser at a two-week interval with a spot size of 3 mm, fluence of 3.5 to 5.5 J/cm², and frequency of 2 Hz with a combination of microlens arrays. At 4 weeks after the final treatment, there was a statistically significant improvement in the modified Vancouver Scar Scale (mVSS) and the patient satisfaction score without any significant complication. A 1,064-nm fractional picosecond laser treatment is a safe and effective method to improve traumatic wound scars with depression.

• Medical Lasers
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• v.9 no.1
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• pp.6-11
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• 2020

Hydrogels have been developed and used in tissue engineering and regenerative medicine to deliver therapeutics to injured or diseased tissue because of their versatility and properties that can be tailored to match the natural extracellular matrix. Hydrogels can be made with a variety of physical and chemical properties combined with light responsiveness ideal for applications in different fields of medicine that require the spatiotemporal control of therapeutics. Light, as a stimulus, is relatively inexpensive, contact-free, noninvasive with high spatial resolution and temporal control, convenient and easy to use, and allows deep tissue penetration that is relatively harmless. Photoresponsive hydrogels are ideal candidates for on-demand drug delivery systems that are capable of sustained and controlled drug release, minimizing the side effects, and ensuring the activity and efficient delivery of drugs to the target tissue.

• Medical Lasers
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• v.10 no.4
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• pp.201-206
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• 2021

The recent development of new surgical techniques using lasers has increased the opportunities for open surgery involving minimal manipulation and faster and more accurate removal of lesions. The increasing use of laser technology requires nurses to play an extensive role. As assistants, nurses play an important role in maintaining the efficacy and safety of the laser device. In addition, they are also responsible for providing pre-and post-operative care to patients. Therefore, nurses should be aware of how to proceed with operative laser treatment for all surgical procedures and the steps for maintaining safety prior to, during, and after laser treatment. This review provides in-depth knowledge for nurses undertaking continuing education on lasers and patient care in the field of gynecology.

• Proceedings of the KWS Conference
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• 2002.10a
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• pp.187-192
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• 2002

Applicability of laser micro welding process to the fabrication of medical devices was investigated. Austenitic stainless steel wire (SUS304) was spot melted and crosswise welded, which is one of the most possible welding process for the fabrication of medical devices, by using a Nd-YAG laser. Effects of welding parameters on the microstructure, tensile strength and corrosion resistance were discussed. In the spot melting, melted metal width decreased with decreasing the input energy and pulse duration. Controlling the laser wave to reduce laser noise which occurred in the early stage of laser irradiation made reasonable welding condition wider in the welding condition of small pulse duration such as 2ms. The microstructure of the melted metal was a cellular dendrite structure and the cell size of the weld metal was about 0.5~3.5 ${\mu}{\textrm}{m}$. Tensile strength increased with the decrease of the melted metal width and reached to a maximum about 660MPa, which is comparable with that for the tempered base metal. Even by immersion test at 318K for 3600ks in quasi biological environment (0.9% NaCl), microstructure of the melted metal and tensile strength hardly changed from those for as melted material. In the crosswise welding, joints morphologies were classified into 3 types by the melting state of lower wire. Fracture load increased with input energy and melted area of lower wire, and reached to a maximum about 80N. However, when input energy was further increased and lower wire was fully melted, fracture load decreased due to the burn out of weld metal.

• Clinical Endoscopy
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• v.51 no.6
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• pp.513-526
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• 2018

White light imaging (WLI) may not reveal early upper gastrointestinal cancers. Linked color imaging (LCI) produces bright images in the distant view and is performed for the same screening indications as WLI. LCI and blue laser imaging (BLI) provide excellent visibility of gastric cancers in high color contrast with respect to the surrounding tissue. The characteristic purple and green color of metaplasias on LCI and BLI, respectively, serve to increase the contrast while visualizing gastric cancers regardless of a history of Helicobacter pylori eradication. LCI facilitates color-based recognition of early gastric cancers of all morphological types, including flat lesions or those in an H. pylori-negative normal background mucosa as well as the diagnosis of inflamed mucosae including erosions. LCI reveals changes in mucosal color before the appearance of morphological changes in various gastric lesions. BLI is superior to LCI in the detection of early esophageal cancers and abnormal findings of microstructure and microvasculature in close-up views of upper gastrointestinal cancers. Excellent images can also be obtained with transnasal endoscopy. Using a combination of these modalities allows one to obtain images useful for establishing a diagnosis. It is important to observe esophageal cancers (brown) using BLI and gastric cancers (orange) surrounded by intestinal metaplasia (purple) and duodenal cancers (orange) by LCI.

• Current Optics and Photonics
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• v.2 no.4
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• pp.356-360
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• 2018

We demonstrate continuous-wave operation of an all-fiber thulium-holmium codoped laser operating at a wavelength of 1706.3 nm. To realize laser operation in the short-wavelength region of the emission-band edge of thulium in silica fiber, we employ fiber Bragg gratings having resonant reflection at a wavelength around 1700 nm as a wavelength-selective mirror in an all-fiber cavity scheme. We first examine the performance of the laser by adjusting the central wavelength of the in-band pump source. Although a pump source possessing a longer wavelength is observed to provide reduced laser threshold power and increased slope efficiency, because of the characteristics of spectral response in the gain fiber, we find that the optimal pump wavelength is 1565 nm to obtain maximum laser output power for a given system. We further explore the properties of the laser by varying the fiber gain length from 1 m to 1.4 m, for the purpose of power scaling. It is revealed that the laser shows optimal performance in terms of output power and slope efficiency at a gain length of 1.3 m, where we obtain a maximum output power of 249 mW for an applied pump power of 2.1 W. A maximum slope efficiency is also estimated to be 23% under these conditions.