Q-switched Neodymium-doped Yttrium Aluminum Garnet Research Articles

Comparison of Q-Switched Nd:YAG LASER with 10% Azelaic Acid versus Fractional CO2 LASER with 10% Azelaic Acid in the treatment of Post Inflammatory Hyperpigmentation secondary to Acne

Background:Post inflammatory hyperpigmentation (PIH) secondary to acne is a common undesirable sequela following acne that leads to psychological distress and a sense of incomplete treatment among the patients with acne. Few studies have been done in regard to address this condition, and no definite treatment or clear ranking of treatment modalities is available as of yet.Aims:The aim of our study was to assess and compare the efficacy and safety of 1,064-nm Q-switched neodymium-doped yttrium aluminum garnet (QSNY) laser with 10% azelaic acid versus Fractional carbon dioxide (FCO2) laser with 10% azelaic acid in the treatment of post acne pigmentation.Materials and Methods:Seventy patients with PIH secondary to acne were recruited in this study. The patients were randomized into two groups, Group A and Group B, of thirty-five patients each. Patients in group A underwent QSNY laser, while Group B received FCO2 laser. 10% azelaic acid cream was administered to both groups. Both groups received a total of 5 treatment sessions, with 3 weeks interval between each setting. The efficacy and safety of both modalities were assessed using the quartile grading score(QGS), post acne hyperpigmentationindex(PAHPI), patient satisfaction score, and documentation of adverse effects.Results:At the end of five sessions, significant improvement in QGS, PAHPI and patient satisfaction (P < 0.001, respectively) was seen in both groups. The mean PAHPI significantly reduced after the third setting and was followed by drastic reduction in the following settings. However, significantly superior results were noted in Group A with respect to all assessments. Side effects noted were mild and transient, except two patients of Group B who developed further pigmentation over the treatment areas.Conclusion:This study shows that both QSNY laser and FCO2 laser can be used to treat post-acne pigmentation; however, QSNY laser should be preferred with respect to efficacy and safety, especially in the Indian population, owing to the higher risk of pigmentation following FCO2 laser.

Melasma removal using Q-Switched Neodymium-doped Yttrium Aluminium Garnet laser toning and high-intensity focussed ultrasound.

To evaluate the effectiveness of combining high-intensity focussed ultrasound and a Q-switched neodymium-doped yttrium aluminium garnet 1064nm low-fluence toning laser in the treatment of melasma. The experimental study was conducted from November 2020 to August 2021 at the medical physics laboratory, College of Medicine, Mustansiriyah University, Baghdad, Iraq, and comprised individuals of either gender aged >25 years having mixed form melasma in malar and forehead areas. Each participant received high-intensity focussed ultrasound treatment on the right side. After 2 weeks, Q-switched neodymium-doped yttrium aluminium garnet 1064nm low-fluence toning laser was applied to the melasma patches 4 times at one-week intervals. Melasma area and severity index scores were noted at baseline and at each visit for each patient. Visual analogue scale was used for objective evaluation. After the 4 laser sessions, all the patients completed a 3-month follow-up. Data was analysed using SPSS 24. Of the 25 subjects, 15(60%) were females and 10(40%) were males. The overall mean age was 41.6±8.46 years (range: 22-60 years). There was a significant improvement with high-intensity focussed ultrasound (p<0.05). In the 3rd laser session, there was a significant difference in melasma area and severity index score of 2.48 for the right side and 3.12 for the left side (p<0.05). In the 4th session, there was a significant difference in melasma area and severity index score of 1.68 for the right side and 2 for the left side (p<0.05). No post-inflammatory hyperpigmentation or rebound was noted. High-intensity focussed ultrasound combined with toning laser was more effective than Q-switched neodymium-doped yttrium aluminium garnet 1064nm low-fluence laser alone in removing difficult melasma from the malar area in the 2nd, 3rd and 4th sessions, and from the forehead in the 3d and 4th sessions.

Retinal injury from a laser skin resurfacing device during medical tourism: a public health concern

BackgroundLaser skin resurfacing is a popular cosmetic procedure for noninvasive skin rejuvenation. Since health insurance plans often do not cover these types of procedures, patients often pay out of pocket. Consequently, there is an incentive to go abroad, where prices are more affordable. However, practitioners in destination countries may lack rigorous training on laser safety, regulatory oversight, or licensing, especially on devices used for “cosmetic” procedures. In certain cases, this can lead to tragic outcomes, especially when underqualified practitioners operate medical-grade laser devices.Case presentationA 29-year-old woman suffered a retinal burn from a handheld Q-switched neodymium-doped yttrium aluminum garnet (Nd:YAG) laser pulse device used to perform skin resurfacing treatment at a medical spa in Vietnam. The patient was not adequately informed about the potential risk to her vision and was not provided with any eye protection. A momentary, unintended laser exposure to the patient’s right eye led to irreversible vision loss due to a macular burn. This incident caused immediate pain, followed by the sudden appearance of floaters, along with a retinal and vitreous hemorrhage. Despite treatment with off-label bevacizumab for the development of a choroidal neovascular membrane, vision remained at the level of counting fingers because of the presence of the macular scar.ConclusionWhen utilizing laser-based devices, it is crucial to employ safety measures, such as the wearing of safety goggles or the use of eye shields to protect ocular tissues from potential damage. The growing availability of cosmetic laser devices presents a substantial public health risk, because numerous operators lack adequate training in essential safety standards, or they neglect to follow them. Furthermore, patients seeking services abroad are subject to the regulatory practices of the destination country, which may not always enforce the requisite safety standards. Further research is needed to determine regional and global incidence of laser-related injuries to help direct educational and regulatory efforts.

Temperature Distribution Within an Ignition Kernel Initiated by a Laser-Induced Plasma

The sizes of, and temperature distributions within, ignition kernels initiated by a Q-switched neodymium-doped yttrium aluminum garnet laser-induced plasma in an unconfined lean premixed hydrogen-air upward jet flow are investigated. The experiments involved a range of jet velocities and a range of deposited laser energies at a fixed height above the exit along the axis of a burner. The growth of, and the temperature distributions within, the ignition kernels, as affected by the size and the energy distribution of the laser-induced plasma, are monitored with an infrared camera. The initial ignition kernels’ areas are larger with higher laser pulse energies and remain unchanged up to 20 μs and then increase by factors of up to 3 at 100 μs. The change in the kernel area caused by the jet velocities is less than 1.5%. An increase of the bulk velocity by 190% decreases the ignition kernel temperature by 6%. This reduction in the ignition kernel temperatures is because of an increase in energy losses by a factor of 2 and decreases in heat releases by 2% at 10 μs and by 11% at 100 μs. The present contributions are: measurements of and insights into temperature distributions and kernel development rates during the laser-induced plasma ignition process at different deposited energies and flow velocities.

Pilot Study to Demonstrate Improvement in Skin Tone and Texture by Treatment with a 1064 nm Q-Switched Neodymium-Doped Yttrium Aluminum Garnet Laser.

The 1064 nm Q-switched neodymium-doped yttrium aluminum garnet (QS Nd:YAG) laser was developed to treat unwanted pigmentation in the skin such as lentigines caused by photoaging, and tattoos from dye/ink insertion. This laser has also been used for non-ablative epidermal rejuvenation (skin toning). To evaluate changes in skin tone, skin texture and overall improvement after a series of treatments with the QS Nd:YAG laser. Participants received seven full-face treatments with M22 or Stellar M22, a 1064 nm QS Nd:YAG laser, at 2-week intervals. The investigators and participants evaluated the improvement in skin tone and texture at 1, 3 and 6 months after the last treatment. Patient satisfaction, patient discomfort, downtime and adverse events were recorded. Histological changes in the treated area were also evaluated. Thirteen women with a median age of 45 years (range, 34-61 years) were included in the study. The majority of the participants (53.9%) had skin type VI. One month after the last treatment session, 38% of participants reported good to very good improvement. This value increased to 100% participant improvement at both the 3-month and 6-month follow-up visits. The reduction in melanin index and the histological analysis demonstrated that the laser procedure contributed to a reduction in epidermal melanin content. Treatments were not associated with high levels of pain or discomfort. The most common immediate post-treatment response was erythema and edema. Most participants were satisfied with the resulting treatment outcome. Skin treatment with the 1064 nm QS Nd:YAG laser module on the M22 and Stellar M22 devices, using a large spot size, low fluence, moderately high repetition rate, improves skin tone and texture in patients with skin types II-VI.

Novel 532-nm Q-switched Nd: YAG laser for the treatment of melasma and rejuvenation: a prospective, randomized controlled comparison with 1,064-nm Q-switched Nd: YAG laser.

Melasma is a common pigmentary and photoaging disorder. Although various treatments, including 1,064-nm Q-switched neodymium-doped yttrium aluminum garnet (QS-Nd: YAG) laser toning, are available for melasma, results are often unsatisfactory. We aimed to determine the efficacy and safety of 532-nm QS-Nd: YAG laser (shortwave toning) in patients with melasma and facial rejuvenation. Fifty-two patients were recruited to receive either 1,064-nm QS-Nd: YAG laser or 532-nm QS-Nd: YAG laser every 2 weeks for 8 sessions and a 2-month follow-up visit in a randomized controlled double-blinded study. The primary outcome measure was the Melasma Area and Severity Index (MASI) score. Dermoscope and high-frequency ultrasound (HFUS) were used to assess the improvement of melasma and photoaging. 532-nm QS-Nd: YAG laser achieved significantly higher improvement in the MASI score (P = 0.000). The Dermoscopic melasma score (DMS) displayed significant change and confirmed the improvement. HFUS showed a significant decrease in the thickness of the subepidermal low-echogenic band (SLEB) and increases in dermal thickness and dermal density in both groups (P = 0.000 for all). The rate of very satisfied responses was significantly higher in the 532-nm laser group (P = 0.001). There was no significant difference in the visual analog scale pain assessment score (P = 0.248) and recurrence rate (P = 0.734) between the two groups. 532-nm QS-Nd: YAG laser (shortwave toning) proved to be an effective and safe treatment for melasma and rejuvenation. Shortwave toning was significantly better for pigmentation clearance, while 1,064-nm laser showed better improvement in skin rejuvenation.

Nevus of Ota: Combination Treatment with Q-Switched Neodymium-Doped Yttrium Aluminum Garnet Laser and Fractional CO2 Laser.

Nevus of Ota is a facial dermal melanocytic hamartoma occurring more commonly in Asians. The mainstay of treatment is 1064-nm Q-Switched neodymium-doped yttrium aluminum garnet (Nd:YAG) laser, which has shown variable results in pigmented skin. The aim of this study was to determine whether Q-Switched Nd:YAG laser treatment combined with fractional CO2 laser is more efficacious than Q-Switched Nd:YAG laser alone. This was a prospective study with 81 patients. The patients were randomly divided into two groups. Group 1 received 1064-nm Q-Switched Nd:YAG laser alone and group 2 in addition received a fractional CO2 laser as well. Both groups received six sittings at monthly intervals. The treatment response was documented with physician global assessment (PGA) and patient's treatment satisfaction on Wong-Baker Facial Pain Scale (WBFPS). Dermoscopic evaluation was done to see subsurface pigment clearance. In the combination group, 25% of patients had more than 50% improvement as compared with 5.71% in group 1. To achieve a mean PGA score of 1.4, it took six sessions for group 1 versus only four for group 2. Dermoscopic evaluation showed faster pigment clearance in the combination group. Combining two lasers shows statistically significant faster and greater degree of improvement as compared with Q-Switched Nd:YAG laser monotherapy in nevus of Ota.

Magnetic-Field-Confined Laser Induced Kohl Plasma: Elemental Analysis and Plasma Characterization.

In this study, the laser-induced kohl plasma is produced in the vicinity of the transverse magnetic field (B) of 0.8 T. A Q-switched neodymium-doped yttrium aluminum garnet (Nd:YAG) pulse laser (λ = 1064 nm, E = 100 mJ, τl = 8 ns) is focused to produce the kohl plasma with and without a B, and the plasma emissions are recorded using a laser-induced breakdown spectroscopy (LIBS) spectrometer. The comparison of the emission spectra shows that most of the emission line intensities are reduced due to the field. However, except for a few lines which are enhanced up to three times. However, the plasma parameters such as electron temperature (Te), electron number density (Ne), and plasma frequency (ʋp) have been increased. Furthermore, thermal beta (βt) is also estimated analytically, and its value is smaller than one (β < 1) for all samples, which confirmed the evidence of magnetic confinement effects. According to the analysis of the kohl emission spectrum, several elements were detected (Pb, Ca, Mg, Fe, Cr, and Zn), among which lead (Pb) and chromium (Cr) may cause chronic health effects like contact dermatitis and neurological diseases. A calibration-free LIBS (CF-LIBS) method is used for the quantitative elemental analysis of the detected elements, which yields Pb as 15-74% and Cr as 3%, which exceed the permissible limit for kohl.

Clinical Study of a Q-Switched Neodymium-Doped Yttrium Aluminum Garnet Laser with Different Parameters in the Treatment of Chloasma: A Randomized-Controlled Trial.

Objective: To explore the clinical efficacy of a Q-switched neodymium-doped yttrium aluminum garnet (Nd:YAG) laser with different parameters in the treatment of chloasma. Methods: In this study, 30 patients with chloasma, symmetrically distributed on the left and right sides of the face and who were treated with a Fayton Q-switched 1064 nm Nd:YAG laser, were recruited. The patients were randomly selected for the treatment of facial lesions on the left and right sides of the face using a spot diameter of 9 mm and an energy density of 0.8 J/cm2 on one side, and, on the opposite side, a spot diameter of 6 mm with an energy density of 1.2 J/cm2. The laser frequency was 5 Hz and treatment was conducted once every 7-10 days and repeated eight times as a course of treatment. At the end of the course of treatment, as well as 1, 3, and 6 months after treatment, front-facing images and 45° left- and right-side images were taken, respectively. The curative effect of the treatment was evaluated using the Melasma Area Severity Index (MASI) score. Results: The results of this study showed that the total effective rate of a Fayton Q-switched 1064 nm Nd:YAG laser in the treatment of chloasma was 60%. Conclusions: Using a Q-switched 1064 nm Nd:YAG laser represents a safe and effective approach for the treatment of chloasma. The therapeutic effects of the parameter sets, that is, a spot diameter of 9 mm and an energy density of 0.8 J/cm2, and a spot diameter of 6 mm with an energy density of 1.2 J/cm2, were similar. The treatment time and average effective times of the latter were relatively shortened. Clinical Trial Registration number researchregistry6799.

Treatment protocols and efficacy of light and laser treatments in post-acne erythema.

Post-acne erythema is described as erythema due to release of inflammatory cytokines, dilatation of microcapillaries within papillary dermis and thinning of epidermis. The erythema usually fades; however, it can persist for months. In this review, we decided to evaluate efficacy of light and laser treatments in acne-induced erythema. We searched PUBMED, Embase, Cochrane, and Google Scholar for relevant key words. Inclusion criteria were randomized clinical trials (RCTs) that evaluated efficacy of laser or light in PAE until September 2021. Twelve RCTs were selected for the final assessment. Light and laser treatments included pulsed dye laser (PDL), intense pulsed light (IPL), Q-switched neodymium-doped yttrium aluminum garnet (QS Nd:YAG), fractional photothermolysis, alexandrite, solid-slate 589-1319nm, and pro-yellow laser. Light and laser treatments are effective treatment modalities in reduction of acne-induced erythema along with active acne lesions and atrophic acne scars.

Comparison between the use of intense pulsed light and Q-switched neodymium-doped yttrium aluminum garnet laser for the treatment of axillary hyperpigmentation.

Axillary hyperpigmentation (AH) is a condition in which axillary skin is darker than the adjacent areas. To date, there is no standard treatment for AH. The Q-switched neodymium-doped yttrium aluminum garnet 1064-nm(QS) laser and intense pulsed light (IPL) are two effective modalities for the treatment of pigmentary disorders; however, the efficacy and safety levels of both treatments for AH have not yet been compared in a controlled study. To evaluate and compare the efficacy and safety of the QS laser and IPL in the treatment of AH. A randomized, split-side study was conducted on 22 subjects; all subjects received a total of five split-side treatments every 2weeks. The efficacy was determined using the melanin index (MI), color chart level using the Pantone SkinTone™ Guide, improvement grading scale (IGS), and patient satisfaction scores at weeks 2, 4, 6, 8, and 10. The results showed that there was no significant difference in MI, color chart level, IGS, and patient satisfaction scores between the two treatments. Both treatments significantly improved AH after three sessions. However, the pain score was lower for IPL treatment. The adverse effects were transient and were found after IPL treatment in one participant (4.45%) who developed hyperpigmentation and another participant (4.45%) who developed erythema. Intense pulsed light therapy is safe and effective for the treatment of AH, with no significant difference in the outcome compared with QS laser treatment.

Comparison of the efficacy and safety between a low-fluence 1064-nm Q-switched neodymium-doped yttrium aluminum garnet laser and a conventional Q-switched 532-nm laser for the treatment of cafe-au-lait macules in 40 Chinese children: a prospective, randomized, parallel-controlled, evaluator-blinded trial.

Cafe-au-lait macules (CALMs) affect the appearance of patients and can result in serious psychological problems. Successful treatments without adverse effects remain challenging. We designed a prospective, randomized, controlled, evaluator-blinded trial on 40 pediatric patients to compare the efficacy between a low-fluence 1064-nm Q-switched Nd:YAG laser and a Q-switched Nd:YAG 532-nm laser for the treatment of solitary CALMs in children. We randomly assigned participants into 2 groups. We treated those in the first group with 3 sessions of 532-nm QS laser at 1-month intervals, and those in the second group with 6 sessions of 1064-nm LFQS laser at 2-week intervals. We found no significant differences in treatment efficacy (p = 0.14). The 1064-nm laser group referred significantly less pain than the 532-nm laser group (p = 0.0001). Side effects were detected in 5 patients in the 532-nm laser group. The difference of the side effects was statistically significant (p = 0.04). Two patients in 532-nm laser group were recurred and none in 1064-nm laser group. On a univariate logistic regression analysis, lesions with brown color, small size, and irregular edges were significantly associated with better outcomes (> 50% clearance). Multivariate logistic regression analysis found that brown lesions and lesions with irregular edges had higher odds of getting > 50% clearance (p < 0.05). In conclusion, the 1064-nm LFQS laser produced fewer side effects, less pain, and shorter recovery time than the 532-nm laser. Irregular-bordered, smaller, brown lesions improved better than smooth-bordered, larger, light brown lesions. Moreover, the 1064-nm laser may be a better choice for treating large size CALMs. However, no significant differences were found in terms of the treatment efficacy and recurrence.

A study of Q-switched Nd:YAG laser versus itraconazole in management of onychomycosis

Context:Onychomycosis (OM) accounts for 20%–40% of all nail disorders. Slow growth of nails, resistance to antifungal drugs, their side effects, and drug interactions limit treatment options. Q-switched neodymium-doped yttrium aluminum garnet (Nd:YAG) laser is approved for nail clearance of OM, however conflicting reports exist in literature about its efficacy. This study was conducted to compare the efficacy of Q-switched Nd:YAG laser.Aim:The aim of this study was to find the efficacy of Q-switched Nd:YAG laser (1064 nm) management of OM as monotherapy in comparison to itraconazole.Settings and Design:A randomized parallel group, outcome assessor trial was conducted over 18 months from July 1, 2015 to December 31, 2016, at skin center of a tertiary care hospital.Subjects and Methods:In the first group, patients of OM were administered 12 weekly sessions of the laser. Second group was administered itraconazole 200 mg twice a day for 1 week per month for the 3 months. Confirmed cases of OM, who had not received treatment 6 months before presentation, were selected and randomly allocated to two groups of 50 each. Onychomycosis severity index (OSI) and visual analog scale (VAS) score were used to assess nail involvement at the start of study, 3 months and 1 year after enrollment.Statistical Analysis:Clinical profile of patients was analyzed by chi-square test for qualitative variables. For comparison of quantitative variables, Student t test was performed. A 5% probability level was considered as statistically significant (P < 0.05).Results:VAS and OSI showed statistically significant improvement at 3 and 12 months in Group I, while resulting in faster clearance with laser; OSI was comparable in both groups at 12 months. Mycological cure was significantly higher in Group I. Both dermatophytes as well as non-dermatophytes responded well to laser treatment, whereas non-dermatophytes responded better to laser.Conclusions:Q-switched Nd:YAG laser is effective in inducing nail clearance in OM and is better than itraconazole in managing non-dermatophyte OM.

Compact long-working-distance laser-diode-based photoacoustic microscopy with a reflective objective

Photoacoustic microscopy (PAM) has quickly developed into a noninvasive biomedical imaging technique to achieve detection, diagnosis, and monitoring. Compared with Q-switched neodymium-doped yttrium aluminum garnet or optical parametric oscillator lasers, a low-cost and small-size laser diode (LD) used as an alternative light source is conducive to achieving the miniaturization and integration for preclinical transformation. However, the LD’s low peak output power needs the high numerical aperture objective to attain tight focus, which limits the working distance (WD) of the system in only 2–3 mm, resulting in not achieving the backward coaxial confocal mode. Here, we present a compact visible LD-based PAM system with a reflective objective to achieve a 22 mm long WD and a 10 µm lateral resolution. Different depth subcutaneous microvascular networks in label-free mouse ears have successfully reappeared in vivo with a signal-to-noise ratio up to 14 dB by a confocal alignment. It will be a promising tool to develop into a handy tool for subcutaneous blood vessel imaging.

A study on efficacy of high fluence Q-switched neodymium doped yttrium aluminium garnet laser in macular amyloidosis

&lt;p class="abstract"&gt;&lt;strong&gt;Background: &lt;/strong&gt;Macular amyloidosis (MA) typically presents as small, dusky-brown or greyish pigmented macules, treatment of which remains challenging with topical and systemic therapies, however Q-switched neodymium-doped yttrium aluminium garnet (Nd:YAG) laser has proven to be an effective treatment modality to reduce hyperpigmentation. The aim of the study is to study the efficacy of Nd:YAG laser in the management of MA.&lt;/p&gt;&lt;p class="abstract"&gt;&lt;strong&gt;Methods: &lt;/strong&gt;30 female patients were treated with Q-switched Nd:YAG laser at 1064 nm with a spot size of 3 mm at a fluence of 6-7 J/cm&lt;sup&gt;2&lt;/sup&gt;, frequency of 2 Hz, for 350-500 pulses. Total number of pulses decreased with each treatment session as the intensity of the hyperpigmentation decreased. The procedure was repeated at one-month intervals for a total of 6 treatment sessions.&lt;/p&gt;&lt;p class="abstract"&gt;&lt;strong&gt;Results: &lt;/strong&gt;After completion of treatment sessions with Nd-YAG laser 36.66% patients showed &amp;gt;50% improvement in the pigmentation. 66.6% patients were satisfied with the laser treatment. 33.3% patients showed &amp;lt;25% improvement and unsatisfied with the treatment.&lt;/p&gt;&lt;p class="abstract"&gt;&lt;strong&gt;Conclusion: &lt;/strong&gt;MA remains an enigma and a source of concern for the suffering patients and physicians. Q-switched Nd-YAG laser 1064 nm has shown positive response in the reduction of pigmentation in MA.&lt;/p&gt;

Efficacy of the combination of Q‐switched Nd:YAG laser and microneedling for melasma

Melasma is a common, multifactorial, and recurring disease which is not easy to treat. The purpose of this study is to evaluate the efficacy of microneedling in combination with Q-switched neodymium-doped yttrium aluminum garnet laser (QsNd-YAG laser) for treatment of melasma. Fifteen female patients with epidermal or mixed-type melasma on the face were included in the study. Patients were first treated with QsNd-YAG laser, and then with microneedling containing mesotherapy products of biomimetic peptides, at the same session. Modified Melasma Area Severity Index (mMASI) scores were calculated before the first session and again 2weeks after the last session. The same treatment protocol was repeated every 2weeks for five sessions within period of 3months of therapy. The evaluation was performed according to the before and after photographs taken from three angles including 90-degree front and 45 degrees from left and right with the VISIA device. Of the 15 patients included in the study, the mean mMASI scores before and after treatment were 9.2±5.7 (3.8-23.1) and 3.6±4.0 (0.6-16.8), respectively. mMASI scores were significantly reduced after completion of the protocol. Six (40%) patients had "very good response," 4 (26.7%) patients had "good response," and 5 (33.3%) patients were "unresponsive." Six (40%) patients were followed up for 1year, and only 1 patient had a recurrence (6.7%). In addition to the use of photoprotective measures, multimodality treatment including QsNd-YAG laser and microneedling with mesotherapy products containing biomimetic peptides is effective to treat melasma and they work synergistically.

Observation of dual-peak signal-to-noise ratios from plasmas produced in typical laser-induced breakdown spectroscopy (LIBS) experiments

In this work, emission properties of representative trace and major species in steel plasma plumes produced in typical laser-induced breakdown spectroscopy (LIBS) experiments under standard atmospheric conditions are investigated. The correlation between laser fluence and spatially integrated measurements of emission characteristics of the plasma at a typical delay time of 2 µs from the laser pulse onset is thoroughly explored. Q-switched neodymium-doped yttrium aluminum garnet (Nd: YAG) laser emitting at its fundamental wavelength of 1064 nm was employed to generate the plasmas under investigation. The results showed that the signal-to-noise ratio of all lines investigated exhibit irregular behaviour in which two maxima can be identified at specific laser fluence values. This behaviour is attributed to lower standard deviation of the background intensity indicating stable plasma conditions relevant for spectrochemical analysis. Plasma shielding of the incident laser energy, due to electron-atom inverse bremsstrahlung (IB), becomes more critical beyond laser fluencies larger than about 45 J cm-2.

Q-PTP is an optimized technology of 1064-nm Q-switched neodymium-doped yttrium aluminum garnet laser in the laser therapy of melasma: A prospective split-face study

Quickly-pulse-to-pulse (Q-PTP) is the latest dual pulse mode Q-switched neodymium-doped yttrium aluminum garnet [QS Nd:YAG (QSNY)] laser technology that improves efficacy and minimizes side effects. In this study, the safety, efficacy, and advantages of Q-PTP and single-pulse laser mode of 1064-nm QSNY in the treatment of melasma were compared. Twelve healthy women were enrolled in this split-face study. Q-PTP and single-pulse laser mode of 1064-nm QSNY were applied to the treatment side and the control side, respectively. Physician's global assessment, patients' self-assessment and the modified melasma area and severity index (mMASI) scores were used to quantify pigmentation changes. Side effects were recorded. Mean mMASI scores were decreased significantly at the 4th and 12th-week follow-up visit compared to the baseline. Melasma lesion clearance was more than 50% in 58% of patients compared with the baseline. However, both sides of the same patient showed similar therapeutic effect. Minor pain experience and slighter skin erythema reaction were reported in Q-PTP laser mode treatment side compared with the control. No serious complications were found in any of the patients. Q-PTP laser mode of 1064-nm QSNY is an optimal laser therapy in the treatment of melasma with greater safety and superiority.

Spectroscopic estimation of plasma parameters, in the 100–400 ns stage, of a laser-induced plasma in vacuum

This work is focused on the interpretation of the emission spectra in laser-induced plasma observed in the phase at 100–400 ns from after the laser pulse, when the discrete emission lines prevail on the continuum emission, can be important to retrieve the initial stage of expansion. A Q-switched neodymium-doped yttrium aluminum garnet laser has been used for the ablation of a lead sample in vacuum. The observed line profiles, corresponding to different species of lead, were analyzed in terms of delay time. Measurements of parameters of the produced plasmas are performed. The results obtained corroborate the importance of considering nonequilibrium effects in the initial stage of plasma expansion. Also, Stark width for two spectral lines of triply ionized lead is given.

Synthesis and Characterization of Gold-Silver Nanoparticles in Deionized Water by Pulsed Laser Ablation (PLAL) Technique at Different Laser Parameter

Gold and silver nanoparticles (NPs) are physically synthesized using Q-switched neodymium-doped yttrium aluminum garnet (Nd:YAG)-pulsed laser ablation in liquid (PLAL) technique which is a rapid, simple and efficient one-step synthesis. The gold and silver colloidal solutions are separately prepared by 1064[Formula: see text]nm of pulsed laser ablation of metallic target (gold and silver) which is immersed in deionized water. Ultraviolet–visible spectroscopy (UV–Vis) analysis shows the absorption band of gold and silver NPs at [Formula: see text][Formula: see text]nm and [Formula: see text][Formula: see text]nm, respectively. The absorption spectra and color variations of gold and silver NPs at three different laser parameters (output laser energies, target distances from focal point and laser time exposures). High-resolution transmission electron microscopy shows the spherical shape of gold and silver NPs with 34[Formula: see text]nm and 33[Formula: see text]nm diameter of size, respectively, are reported. The aggregation and particle sizes of gold and silver NPs due to minimum energy (75[Formula: see text]mJ) and maximum energy (311[Formula: see text]mJ) are observed.