• Medical Lasers
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• v.10 no.1
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• pp.52-54
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• 2021

There is growing interest in minimizing postoperative scarring after a thyroidectomy. Among the many treatment types, laser therapy, especially picosecond-domain laser therapy, is accepted as a standard method. In the present case, a patient with a pigmented, contracted scar was treated using the combination of a picosecond laser and ablative fractional (AF) CO₂ laser. After 15 sessions of 1,064-nm picosecond with micro lens array (MLA) and AF CO₂ laser application, the patient showed significant improvement in their pigmented lesions and scar contracture with no noticeable side effects for 16 months. These results suggest that a combination of picosecond laser with MLA and AF CO₂ laser can treat pigmented, contracted scars safely and effectively.

• Medical Lasers
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• v.9 no.2
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• pp.142-149
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• 2020

Background and Objectives A picosecond-domain laser treatment using a microlens array (MLA) or a diffractive optical element elicits therapeutic micro-injury zones in the skin. This study examined the patterns of tissue reactions after delivering multiple pulses of 1,064-nm, MLA-type, picosecond neodymium:yttrium-aluminum-garnet laser treatment. Materials and Methods Multiple pulses of picosecond laser treatment were delivered to ex vivo human or brown micropig skin and analyzed histopathologically. A high-speed cinematographic study was performed to visualize the multiple pulses of picosecond laser energy-induced skin reactions in in vivo human skin. Results In the ex vivo human skin, a picosecond laser treatment at a fluence of 0.3 J/cm² over 100 non-stacking passes generated multiple lesions of thermally-initiated laser-induced optical breakdown (TI-LIOB) in the epidermis and dermis. In the ex vivo micropig skin, stacking pulses of 20, 40, 60, 80, and 100 at a fluence of 0.3 J/cm² generated distinct round to oval zones of tissue coagulation in the mid to lower dermis. High-speed cinematography captured various patterns of twinkling, micro-spot reactions on the skin surface over 100 stacked pulses of a picosecond laser treatment. Conclusion Multiple pulses of 1,064-nm, MLA-type, picosecond laser treatment elicit marked TI-LIOB reactions in the epidermis and areas of round to oval thermal coagulation in the mid to deep dermis.

• 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.

• Laser Solutions
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• v.16 no.2
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• pp.1-6
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• 2013

Picosecond lasers are a very effective tool for micromachining metals, especially when high accuracy, high surface roughness and no heat affected zone are required. However, low productivity has been a limit to broadening the spectrum of their industrial applications. Recently it was reported that in the micromachining of copper with a 1064nm picosecond laser, there exist the optimal pulse energy and repetition rate to achieve the maximum volume ablation rate. In this paper, we used a 515nm picosecond laser, which is more efficient for micromachining copper in terms of laser energy absorption, to obtain its optimal pulse energy and repetition rate. Theoretical analysis based on the experimental data on copper ablation showed that using a 515nm picosecond laser instead of a 1064nm picosecond laser is more favorable in that the calculated threshold fluence is 75% lower and optical penetration depth is 50% deeper.

• Medical Lasers
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• v.8 no.1
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• pp.19-23
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• 2019

Background and Objectives The picosecond 755 nm alexandrite laser was first approved by the US FDA in 2012. A previous study described the use of a 1,064 nm picosecond laser with a micro-lens array (MLA) in peri-areolar scarring from breast reconstruction surgery and reported significant improvement in the texture and aesthetic appearance of the scar without other wound complications. The purpose of this study was to evaluate the improvement of overall scarring, not just pigmentation, in the picosecond laser treatment of patients with pigmentations. Materials and Methods Sixteen patients who underwent 1,064 nm picosecond laser treatment from June 2016 to December 2018 were enrolled in this study. Patients received two to six sessions of picosecond laser treatment at intervals of 4 weeks. Before and after the laser treatment, the patients evaluated their own satisfaction score and a physician evaluated the Vancouver Scar Scale. To evaluate the satisfaction score and complication rate, a retrospective chart review was done. Results Seven were female and nine were male. The mean of the patients' satisfaction score before the treatment was 1.44 (interquartile range [IQR], 1-2) and 3.00 (IQR 2.25-3.75) six months after treatment. The mean of the Vancouver Scar Scale before the treatment was 9.69 (IQR 8-11), and 6.25 (IQR 5-7.75) six months after treatment. All the results were statistically significant (p<0.01). Conclusion This study provides evidence that the use of a 1,064 nm picosecond laser treatment for pigmented scars can be effective in improving the pigmentation and overall scar status, including vascularity, height, and pliability, with the results of a decrease in the VSS scores between treatments.

• Medical Lasers
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• v.10 no.1
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• pp.31-36
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• 2021

Background and Objectives Several predicted optimal parameters for laser treatment have been suggested, making the settings subject to variation. Thus, picosecond lasers may require more data and studies to optimize the laser parameters, increase the efficacy of each session, and minimize the total number of sessions. This study evaluated the results of picosecond laser tattoo removal in variable locations, focusing on the aesthetic outcome, number of procedures, and adverse effects. Materials and Methods Nine patients who underwent picosecond laser treatment from February 2014 to July 2020 were enrolled. Before the procedures, the required number of sessions was estimated using the Kirby-Desai scale. At the end of the treatment, the patients assessed their satisfaction. The patient and two plastic surgeons assessed the clearance of the tattoo. Results The mean of the clearance was 86.6% in both the patient and investigators assessment. The patients reported satisfaction for an average score of 5.1 ± 0.78 for the aesthetic outcome, 4.5 ± 0.78 for pain, 4.1 ± 0.92 for the number of procedures, and 4.7 ± 0.97 for adverse effects. The average number of actual procedures was 6.7 ± 1.20. The average Kirby-Desai score was 7.1 ± 1.45. Their correlation coefficient was 0.803, which is considered a strong positive correlation. Conclusion Picosecond lasers have a remarkable ability to degrade smaller tattoo pigments through a photoacoustic effect. Moreover, a picosecond laser treatment for tattoo removal can be a safe and effective method. Picosecond lasers are a promising technology with the potential to optimize the treatment of tattoos.

• Journal of the Korean Society for Precision Engineering
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• v.27 no.2
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• pp.25-28
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• 2010

The micro fabrication on the mold material using picosecond laser ablation processing has been studied. We used the two kind of system with picosecond laser. First one is two mirror type scanner and telecentric f-theta lens. Second one is X-Y stage and objective lens. By using these system, the $100{\mu}m$ size chess patterning and $2{\mu}m$ size patterning was fabricated. Especially $2{\mu}m$ size patterning on the mold material can be used as the decorative rainbow color logo for industrial field. In this paper, it is proved the picosecond laser is effective tool for the laser ablation processing.

• Medical Lasers
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• v.9 no.1
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• pp.84-87
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• 2020

Post-acne erythema (PAE) is one of the major problems during or after treatment of acne vulgaris with any modality. A variety of therapeutic options have been described with various clinical outcomes and side effects. We report here on treating a patient with PAE using 595-nm picosecond-domain neodymium:yttrium-aluminum-garnet (Nd:YAG) laser. After four sessions of treatment, the patient displayed nearly complete improvement and no remarkable adverse effects. To the best of the authors' knowledge, this is the first case of the effective treatment of PAE using a 595-nm picosecond-domain Nd:YAG laser. We recommend that using a 595-nm picosecond-domain Nd:YAG laser can be both an effective and safe treatment option for treating PAE.

• Medical Lasers
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• v.8 no.1
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• pp.32-34
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• 2019

Postinflammatory hyperpigmentation (PIH) is a reactive hypermelanosis of the skin that occurs as a result of variable inflammatory processes, such as trauma, and many inflammatory conditions. Although a range of modalities of managing PIH have been reported, the treatment of PIH is challenging. In this report, a patient with PIH was treated using picosecond-domain Nd:YAG lasers. After three sessions of 1,064-nm picosecond-domain Nd:YAG laser treatment, the patient showed almost complete improvement with no remarkable side effects or recurrence over the duration of six months. Overall, 1,064-nm picosecond-domain Nd:YAG laser can be used effectively and safely for treating pigmented lesions in the dermis, particularly PIH, in Asian patients.

• Medical Lasers
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• v.8 no.2
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• pp.87-89
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• 2019

Post inflammatory hyperpigmentation (PIH) is a reactive hypermelanosis of the skin that occurs as a result of various inflammatory responses such as surgical procedure, trauma, and many inflammatory conditions. There are several reported studies of various modality in managing PIH. However, the treatment of PIH can prove to be challenging. In this report, we treated a patient with PIH using picosecond-domain Nd:YAG lasers. After ten sessions of 1,064-nm picosecond-domain Nd:YAG laser treatment, the patient presented considerable improvement with no remarkable side effects or recurrence over the duration of 6 months. We suggest that a 1,064-nm picosecond-domain Nd:YAG laser can be effectively and safely used for treating pigmented lesions resulting from surgical procedure in the skin of Asian patients.