Level Laser Research Articles

Low- level laser: cost of therapy fornipple trauma

Abstract Objectives: to measure the micro-cost of local laser therapy (LL) and transcutaneous laser therapy application by Irradiation Laser Intravascular of Blood (ILIB) to treat nipple trauma and compare the most effective and efficient alternative treatment. Methods: a cross-sectional analytical and quantitative study with analysis on the micro absorption cost, implemented as a clipping, from a randomized clinical trial that used two types of laser therapy to treat nipple trauma due to breastfeeding. The sample consisted of 101 nipple lesions. Patients were randomized into three groups (Control - CG, Local Laser -LLG and ILIB-ILIBG). Materials used, direct labor (DL) and laser equipment were predictors of costs. The delta calculation (effect size) was the indicator for measuring effectiveness and efficiency. Results: after three sessions, the average final cost was R$ 40.04for CG, R$ 53.55for LLG and R$ 67.29for ILIBG. After three sessions of treatment, ILIBG showed a great reduction in the lesion area, but with a higher cost (p<0.05). Conclusions: ILIBG had a better effect on healing the nipple trauma when compared to CG and LLG, even though it is more expensive, it suggests a positive cost-benefit and the most effective and efficient alternative treatment.

The thermal effect of cladding power stripper for high power fiber lasers

Lasers have been widely used in many fields such as machinery, medicine, and military. With the development of fiber lasers, high power lasers become more and more desirable. Although lasers with power level of kilowatt or even million watt have been fabricated, there could be many problems associated with the increased power. The most important problem needed to be solved is how to strip unnecessary pump light before laser emit out from the devices. With the progresses in the past years, people have developed some methods to overcome this problem. However, these methods also have some disadvantages, such as too small stripping area to achieve high power light emission, and unsuitability of the technology for mass production. Glue method is the earliest proposed way for stripping the unnecessary light. Its biggest advantage is the simple process. But it also has a big disadvantage that glue cannot endure underhigh temperature in the range of 60°C to 70°C. To solve this problem, people have made attempts for years by either forced cooling or rasing the bearing temperature of glue, however, there is still no good solution. In fiber lasers, the superfluous pump light is dense, which has contributions from the pump light that is not fully absorbed by gain fiber and from high order laser due to misalignment elements. To efficiently strip the inner cladding light, and to get higher stripping power and more uniform heat distribution, we have used an optimized high index glue to fabricate the cladding power stripper. The basic idea is to improve the heat distribution in cladding power stripper by handle the structure of double clad fiber. The specific method is to rotate the cutting area at outsourcing, so the pump light can emit out uniformly, and the glue will have a low working temperature. Experiments and FE simulation are conducted to study the thermal effect of cladding power stripper. The results show that the highest stable operating temperature is 50.0°C when the cladding power is 132 W, and the temperature of cladding power stripper increases linearly with the increase of the stripping power. There is no overheating point in the stripper in the test indicating that the proposed method is applicable for kilowatt level fiber lasers. The experimental results are consistent with FE simulations, which verifies the correctness of simulation model and parameters. As the working temperature is much lower than 60°C, the results demonstrate that such stripper structure is reliable and its properties can be well described by simulations. Such a cladding power stripper only changes the structure of the double clad fiber to optimization the heat distribution, and the result shows this method are useful. The cooling effect of heat source was not perfect, which is the reason why the stripper temperature is 50.0°C when stripping power are only 132 W. So there is an opportunity to change the structure of heat source or use water-cooling or air-cooling to auxiliary heat dissipation for heat source. If both the structures of double clad fiber and heat source are optomized, this cladding power stripper can be used for million watts level lasers without problem. In addition, the simple structure of glue method cladding power stripper, enables its mass production, therefore, this stripper has a great application potential.

The M1/M2 Pattern and the Oxidative Stress are Modulated by Low- Level Laser in Human Macrophage

Objective: This study investigated the phototherapy (PhT) effect on U937 cells activated by lipopolysaccharide (LPS) from E. coli. PhT has been reported to control the release of inflammatory mediators from different cells activated by LPS. It is unknown if the macrophage M1/M2 pattern as well as the reactive oxygen species (ROS) generation and the pro- and anti-inflammatory cytokines secretion from U937 cells can be influenced by PhT. Methods: The U937 cells, a human monocytic cell line, were cultured and matured to macrophages in a medium with LPS and irradiated (660 nm) at 4.5 J/cm2. Apoptosis was standardized with Annexin-V and propidie iodate (PI) and the cytotoxicity assay evaluated by MTT. ROS was measured by DCFH-DA. The cytokines, chemokines, NF-κB and Sp1 activity were measured by ELISA. PhT was studied in the presence of a Sp1 inhibitor, mithramycin. Results: The pro-inflammatory cytokines and chemokines, ROS and NF-κB were downregulated by PhT. On the contrary, IL-10, arginase, PGC-1β and glutathione were upregulated. The Sp1 activity was increased after PhT to values higher than those from cells only LPS-treated; oppositely the mithramycin abrogated this effect. Conclusion: The PhT restored the macrophage polarization toward M2 pattern as well as balanced the oxidative stress and modulated the immune response upregulating the IL-10 secretion by a mechanism in which Sp1 transcription factor has a crucial role.

Shift and broadening of quasi three level emission lines in Nd3+:YAG laser crystal influenced by input energy

The pumping energy effect on fluorescence emission properties of Nd3+:YAG laser host pumped by flashlamp was studied over the range of 18–75J. The spectral widths and shifts of the quasi three level inter-Stark transitions at 938.5 and 946.0nm lines within the respective intermanifold transitions of 4F3/2→4I9/2 were investigated. The quasi three level emission lines shifted toward the longer wavelength (red shift) and broadened by increasing pumping energy. This was attributed to the thermal population as well as one-phonon and multi-phonon emission process in the ground state. These phenomena obstruct the output performance of quasi three level lasers.

Two Level Metal Vapor Lasers with Thermal Creation of Population Inversion

We present a new technique for direct conversion of thermal energy into coherent radiation. The near-surface layer of evaporated excited atoms of rare earth metals is proposed to be used as a converter. There is an inverted population in this layer. Operation principles of two level lasers on the transitions to the ground state using Eu are considered. The fact of detachment of Sm atoms in the excited 4f(N-1)5d6s2 state during the thermal evaporation process has been proved experimentally.

Corner-pumped Yb:YAG lasers

A corner_pump method for high_power quasi_three_level lasers is reported. The de sign uses a slab laser configuration with the incident pump light from the slab corner. We present an analytic description of pumping absorption, pumping bright ness, doping concentration and crystal dimension for the corner_pumped composite Yb:YAG laser. In the experiments a maximum continuous-wave output power of 400 W with slope efficiency 28% was achieved. This result shows the validity of corn er_pumping concept and its feasibility in the development of high_power solid_st ate lasers.

Dynamic behavior analysis of the 3μm and 2μm cascade Ho3+:ZBLAN fiber lasers

A numerical study of the transient behavior, including upper level ions and laser power relaxation oscillation, of Ho3+:ZBLAN fiber laser is presente d based on the propagation-rate equations. The power propagation equations for pump a nd signal have been treated differently by neglecting the z-dependence of t he fiber laser parameters, for the sake of numerical simplicity. The results sho w that upper level ions of 5I6 and 5I7 manifolds relax alternati vely and go to steady state after the first relaxation oscillation and monotonou s decline. Similarly, the 3μm and 2μm laser powers relax alternatively first, then the 3μm laser power declines monotonously while the 2μm laser power incre ases monotonously, both of them go to steady state after the second relaxation o scillation. Moreover, peak powers of the 3 μm and 2 μm lasers in the course of relaxation oscillation are far larger than that when steady state is reached.

Lipids and fatty acids of the benthic marine harpacticoid copepod Heteropsyllus nunni Coull during diapause: a contrast to pelagic copepods

Many free-living copepods produce and store lipids prior to entering diapause (long-term dormancy). Heteropsyllus nunni Coull is the only marine harpacticoid copepod known to undergo any form of diapause. This study presents the first information on the types of lipids and fatty acids produced for long-term diapause in this benthic species. Sexually immature adults of H. nunni undergo diapause within a pliable self-made cyst. Prior to entering diapause (which lasts 3–4 months), they produce and store large amounts of orange lipid. The lipids apparently are utilized during diapause. Although some residual lipids remain, chiefly around the gonads, after the copepods emerge from their cysts, the lipid stores are visibly reduced. Typically, the copepods mate and produce eggs within 48 h after diapause is terminated. Light level and confocal laser scanning microscopy revealed that the lipid stores are distributed throughout the body in numerous oil droplets and not as a single oil sac, as seen in many marine calanoid copepods prior to overwintering (winter diapause). Transmission electron microscopy showed lipid spheres within the gut epithelium and large droplets of lipids stored extracellularly. Confocal laser scanning microscopy of copepods in pre-diapause, during diapause (encysted), post-diapause (recently excysted), and in reproductive condition, revealed that lipid stores are reduced following diapause, but are not totally absent. Analysis of lipid classes showed that H. nunni store predominantly wax esters/sterol esters (83% of total lipids) during diapause. The predominant lipid is most likely wax esters, as sterol esters typically are found only in small amounts in copepods. Fatty acid (FA) profiles of the copepods in diapause showed 16:0 to be most abundant followed by 16:1n-7 and 18:0; other FA occurred at concentrations <10% of total FA. Three polyunsaturated fatty acids (PUFA), 20:5n-3, 18:2n-6 and 20:4n-6, were found at concentrations <2% of total FA. These PUFA are "essential fatty acids" in H. nunni, obtained through dietary sources. The lipid classes and fatty acids present in H. nunni during diapause are compared to those of other copepods, some in a state of diapause and others not. It appears that lipid class and FA profiles are indicative of genetic makeup, type of diet or amount of food consumed prior to dormancy. Some classic paradigms of lipids and their association with copepod diapause are re-evaluated.

DensMat: fully time-resolved simulation of two-step pulsed laser excitation of atoms in highly collisional media

A program that simulates and displays the level populations of atomic systems exposed to dual-wavelength (i.e. two-colour) pulsed laser excitation in highly collisional media (such as flames and plasmas) has been developed. The program is based upon a previously published fully time-dependent density-matrix model that describes step-wise excitations of atoms with degenerate states under collision-dominated conditions, and which thus goes beyond the rate-equations formalism. This model can predict such phenomena as Rabi flopping and a.c.-Stark splitting, shifting and broadening. The program can be used as a prediction tool for laser-enhanced ionization, laser-induced fluorescence, fluorescence dip spectroscopy and other two-colour laser-based spectroscopic experiments. The program provides the user with a flexible four-level atomic system, configurable as a one- or two-step excitation ladder, along with an ionization continuum and non-laser-connected level(s) that may act as trap(s) or metastable level(s). Parameters such as level degeneracy, collisional rates and laser pulse widths, shapes, wavelengths, intensities and bandwidths are accessible to the user. The program can display both the time development of the level populations and also level populations versus laser wavelength. This article is an electronic publication in Spectrochimica Acta Electronica (SAE), the electronic section of Spectrochimica Acta Part B (SAB). The hardcopy text is accompanied by a disk containing the program DensMat, an associated on-line help file and manual, an installation program, and data files pertaining to the examples illustrated in this article. The program runs under Windows 3.1 on an IBM-compatible computer.

New room temperature CW laser at 2.82 µm: U3+/LiYF4

Recently, optical studies of U doped LiYF/sub 4/(YLF) have been made. The authors show that U/YLF is a promising IR laser because the crystal field Stark level splitting of the /sub 4/I/sub 9/2/ ground multiplet (1113cm/sup -1/) is larger than in U/sup 3+//CaF (609cm/sup -1/) which makes a four level laser possible at room temperature. However the valence state 3+ is not the most stable state for the actinide ion and the absorption spectra, as well as the pale green colour, show that usually both valence states U/sup 3+/ and U/sup 4+/ are present in the crystal. This Letter reports the first observation of CW laser emission of U/sup 3+/ in LiYF/sub 4/ at room temperature at 2.82 mu m. >

Influence of spatial mode matching in end-pumped solid state lasers

We present investigations on the influence of mode matching on the efficiency of longitudinally pumped solid state lasers. In a theoretical part we enhance an existing model for four level lasers from idealized cylindrical modes to arbitary pump and laser modes in a random relative position thereby neglecting beam deformation due to thermal effects. The theoretical predictions were confirmed experimentally with an end-pumped Nd:YAG rod operated at 1064 nm. To investigate the effect of misalignment on the efficiency we used a Ti-Sapphire pump laser which was displaced relative to the laser beam. To establish the influence of arbitary pump modes on laser performance a diode laser equipped with coupling optics served as pump source for the same resonator. The resulting decrease in slope efficiency compared to the Ti-Sapphire pumped system could be explained in terms of limited mode overlap due to the characteristic pump field distribution produced by the diode coupling optics.

Low-energy optical generation and detection of acoustic pulses in metals and nonmetals

Acoustic pulses have been generated in both metals and nonmetals using a low-energy tunable dye laser emitting 6-ns pulses with 20–210-μJ energies. The acoustic waveforms have been detected optically with a calibrated laser interferometer having improved signal-to-noise ratio. In this fashion, noncontact characterization of nonmetallic, as well as metallic samples of small size, has been shown to be feasible, using a potentially portable system. In addition between the relationship acoustic signal level and incident laser energy (and power density) has been measured for a polyimide-glass-fiber composite material.

Stability of an Idealized Two Level Laser

Stability of an Idealized Two Level Laser