q switched laser

OBJECTIVE: To evaluate the efficacy and safety of 585 nm Q-switched laser in the treatment of acne inflammatory lesions and postinflammatory erythema. METHODS: A total of 25 patients with moderate facial acne, symmetrical distribution of inflammatory lesions and postinflammatory erythema on both sides of the face, were enrolled. Among the 25 patients, 22 patients completed all the treatment and evaluation, and 3 patients were lost to follow-up. 585 nm Q-switched laser was used on a randomly selected side of the face for three times of treatment at a 2 week interval...

A femtosecond Mamyshev fiber oscillator in normal dispersion mode at 1 µm was started reliably and safely by an inexpensive diode-pumped passively Q-switched monolithic microchip laser emitting 300-ps pulses. Four-wave mixing spectral broadening is shown to play a pivotal role in starting the Mamyshev oscillator, owing to the random short and intense temporal fluctuations allowed by its ∼10-nm bandwidth. Systematic studies of the starting dynamics show that a success rate of 100% of the attempts is achieved with modest seed energy, as low as ∼30 nJ from the sub-nanosecond laser, corresponding to ∼100 pJ for the total four-wave mixing signal required to start the oscillation...

Labial lentigines associated with Peutz-Jeghers syndrome are challenging and represent a cosmetic problem. Laser and intense-pulsed light sources (IPLS) can be used to treat these macules. However, there are few guidelines regarding the different types of protocols found in the literature. Thus, the purpose of this study was to review the pertinent literature on lasers and IPLS as therapy for labial lentigines in patients with Peutz-Jeghers syndrome. A detailed literature search was conducted in seven databases (Cochrane Library, Embase, Lilacs, PubMed, SciELO, Scopus and Web of Science) to November 2020...

We developed a customized doubly Q-switched laser that can control the pulse width to easily find weak acoustic signals for photoacoustic (PA) systems. As the laser was constructed using an acousto-optic Q-switcher, in contrast to the existing commercial laser system, it is easier to control the pulse repetition rate and pulse width. The laser has the following control ranges: 10 Hz-10 kHz for the pulse repetition rate, 40-150 ns for the pulse width, and 50-500 μJ for the pulse energy. Additionally, a custom-made modularized sample stage was used to develop a fully customized PA system...

Laser-induced camera damage thresholds were measured for several sensors of three different sensor architectures using a Q-switched Nd:YAG laser in order to determine their pulsed laser-induced damage thresholds. Charge coupled device (CCD), front-side illuminated complimentary metal-oxide semiconductor (FSI CMOS), and back-side illuminated (BSI) CMOS sensors were assessed under laboratory and outdoor environments by increasing the focused laser intensity onto the sensors and recording the sensor output. The damage sites were classified qualitatively into damage types, and pixel counting methods were applied to quantitatively plot damage scale against laser intensity...

To date, there has been little study of comparison between picosecond 532 nm laser and 755 nm Q-switched Alexandrite lasers in the treatment of freckles. To evaluate the efficacy and safety of picosecond 532 nm laser (PS 532) and 755 nm Q-switched Alexandrite laser (QSAL) for treatment of freckles in a split-face manner. Eighteen patients with freckles were enrolled in the study. The right and left sides of their faces were randomly assigned to either a QSAL-treated group or PS 532-treated group. The degree of pain, satisfaction with the results, and adverse events associated with the laser treatment were evaluated using a questionnaire...

Synchronization is important for photoacoustic tomography but some fixed delays between the data acquisition and the light pulse are a common problem degrading imaging quality. Here, we present a simple yet versatile method named "Scissors" to help synchronize ultrasound open platforms (UOPs) for photoacoustic imaging. Scissors is a programmed function that can cut or add a fixed delay to RF data and thus synchronize it before reconstruction. Scissors applies the programmable metric of UOPs and has several advantages: It is compatible with many setups regardless of the synchronization methods, light sources, transducers, and delays...

The past decade has witnessed major advances in the development and system-level applications of photonic integrated microcombs, that are coherent, broadband optical frequency combs with repetition rates in the millimeter-wave to terahertz domain. Most of these advances are based on harnessing of dissipative Kerr solitons (DKS) in microresonators with anomalous group velocity dispersion (GVD). However, microcombs can also be generated with normal GVD using localized structures that are referred to as dark pulses, switching waves or platicons...

Molybdenum carbide (Mo2 C) exhibits enormous potential applications in various optoelectronic and photonic fields due to its remarkably electrical and optical characteristics. Here, we fabricate a high-quality Mo2 C film by the radio frequency magnetron sputtering deposition method. The nonlinear optical response and ultrafast dynamics are thoroughly studied based on open-aperture Z-scan and nondegenerate pump-probe experimental measurements. The open-aperture Z-scan experimental result exhibits a modulation depth of 8...

High-energy Q-switched master oscillator power amplifier systems based on rod-type 4 × 4 multicore fibers are demonstrated, achieving energy up to 49 mJ in ns-class pulses. A tapered fiber geometry is tested that maintains low mode order in large multimode output cores, improving beam quality in comparison to a similar fiber with no taper. The tapered fiber design can be scaled both in the number of amplifying cores and in the dimensions of the cores themselves, providing a potential route toward joule-class fiber lasers systems...

Tantalum aluminum carbide ( T a 4 A l C 3 ) phase ceramic (MAX) material has attracted much attention because of its high conductivity, high strength, corrosion resistance, and good optical properties. However, there are too few reports on lasers with T a 4 A l C 3 -based saturable absorbers (SAs). We prepared and characterized a T a 4 A l C 3 -based SA whose nonlinear absorption performances were achieved at a 2 µm waveband range and which was used in a passively Q -switched (PQS) Tm:YAP laser. In the PQS mode, a maximum average output power of 0...

Quinoline derivative i.e. quinilone yellow with the scientific name [sodium 2-(2, 3-dihydro-1,3-dioxo-1H-inden-2-yl) quinoline-6,8-disulfonate] (SQDS) is analysed for fluorescence resonance energy transfer (FRET). Fluorescence quenching mechanism is studied by employing steady state and transient state spectroscopic measurements. Cobalt Chloride is used as quencher in the present study. Linearity was observed in Stern-Volmer plots for transient state as well as steady state. This was further attributed to a mechanism of collisional quenching...

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Laser therapy is the gold standard method to remove unwanted tattoos. It is available and widely accessible. This study was done to assess the efficacy of the R20 method (multi-time separated passes in one session for 20 min) using Q-switched ND: YAG laser for the removal of tattoos and was compared with the traditional method. Forty patients with 40 Tattoos were included. These tattoos were separated into two halves left and right. One half was treated with a single pass and the other half with R20. Both halves were treated using Q-switched ND-YAG laser with 10 J/cm2, 1...

Melasma is a highly prevalent and cosmetically disfiguring pigmented skin disease. The post-treatment results are often unsatisfactory. A large number of clinical trials have tried to prove the effectiveness of the combination therapy involving laser therapy, but the results have been indeterminate. This study aimed to evaluate the effectiveness of laser treatment for melasma via a systematic review and meta-analysis. We respectively searched 4 databases and clinicaltrials.gov as of June 8, 2021. Two researchers independently searched for literature and extracted data...

Burn injury is a common type of trauma which causes significant morbidity and mortality. Wound healing following burns can be complicated by the formation of hypertrophic scars and the occurrence of post-inflammatory hyperpigmentation (PIH). Neodymium:yttrium aluminum garnet (Nd:YAG) laser might become one of the treatments of choice for hypertrophic scars and PIH. We report a case of post-burn hypertrophic scars and hyperpigmentation in a 20-year-old man. The patient was consulted from the Department of Plastic Surgery and Reconstruction after scar revision...

Flat-top beams have plenty of applications in theoretical and applied research, but they are not eigenmodes of the wave equation. Here, we propose an effective strategy for generating flat-top beams in fibers, which originates from the incoherent superposition of orbital angular momentum (OAM) and fundamental (LP01 ) modes. The designed all-fiber passively Q-switched laser can realize high-quality pulsed flat-top and OAM beam emissions. The normalized root mean square of the flat-top beam is around 4.7%, and the purity of the OAM mode is calculated to be higher than 98%...

Hyperpigmentation of split-thickness skin grafts (STSGs) is commonly found among Asians, and it is also challenging to treat. Although the 1064-nm Q-switched Nd:YAG laser has been used as a standard treatment for skin hyperpigmented lesions, there are limited number of reports focusing on the treatment of hyperpigmentation of STSGs. We aimed to evaluate the efficacy of 1064-nm Q-switched Nd:YAG laser for treatment of hyperpigmented STSGs. Half of each STSGs was treated with the 1064-nm Q-switched Nd:YAG laser, while the remaining was left untreated as comparison...

Rhinophyma is characterized by progressive enlargement of the nasal skin, which is considered to be an advanced stage of phymatous rosacea. Esthetic disfigurement makes surgical treatment necessary for this condition. Hypertrophic scars are the consequence of alterations in the skin's healing process following surgical interventions. Laser may be the treatment of choice in hypertrophic scars. We reported a case of hypertrophic scars following excisional surgery and full-thickness skin grafting due to rhinophyma in an 18-year-old male who was consulted from the Department of Plastic Surgery and Reconstruction...

BACKGROUND: Recently, a low-fluence picosecond (ps) laser is an emerging option for removing pigmented lesions. OBJECTIVES: We aimed to evaluate the efficacy and safety of a 1,064-nm ps Nd:YAG laser as compared to a 1,064-nm Qs Nd:YAG laser for melasma treatment in an Asian. METHODS: Twenty Korean patients with facial melasma were enrolled and randomly treated with a 1,064-nm ps Nd:YAG laser on one side of the face and 1,064-nm Qs Nd:YAG on the other side at 2-week intervals for five sessions...