• Biomedical Science Letters
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• v.6 no.2
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• pp.119-129
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• 2000

The skin is an organ that has many important roles, including protection against infection, regulation of temperature and fluid loss, and sensory function. Injury to the skin, wound repair normally involves: (1) balanced activity of inflammation, (2) the re-epithelial phase and (3) the matrix formation of remodeling phase. Thus, skin wound healing is a finely controlled biological process involving a series of complex cellular interactions. Laser therapy is being implemented with increasing frequency in medicine. Low intensity laser is one that is capable of producing an energy density so low that any biologic alterations are the result of direct irradiation effect, not thermal events. This study was designed to evaluate the efficacy of low intensity laser therapy on skin wound healing in rabbits. A total of 10 male rabbits (New Zealand White Rabbit), age 8 weeks were used. Skin wound were surgically created dorso-lateral on the flank of 10 rabbits (2$\times$2 cm/damage areas). The experimental animals were treated with 5Hz (830 nm wave length) low-intensity laser (MILTA-01 Model) daily for 10 min (1.6 J/$cm^2$) for 12 days. Control animals were sham treated with the laser head. Laser irradiation animals showed a complete remodeling of the epithelial layer, a positive repair of connective tissues, and enhanced the wound closure rate over time as compared to the control animals. Especially, laser irradiation groups improved fibroblast activity, cellular content, granulation tissue formation, and collagen deposition which is resulted in improving the tensile strength of the wound. These findings suggest that laser photostimulation could accelerate healing of open wound in rabbits, and may be benefit in the treatment of open wound, including decubitis ulcers.

• Journal of Korean Physical Therapy Science
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• v.7 no.2
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• pp.533-543
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• 2000

This study was designed to evaluate the analgesic effect of low power GaAsAl laser on the pain threshold of mechanical stimulation using different treatment points, acupuncture point (zusanli) and non-acupuncture points(back). Furthermore, we investigated the analgesic effect of low power GaAsAl laser using the different duration and intensity of laser in mechanical stimulation induced pain behavior. The results were summarized as follows: 1. The threshold of mechanical stimulation was significantly increased by GaAsAl laser stimulation into zusanli point after 15 and 30 min after laser stimulation(P<05). However, the laser stimulation into non-acupoint did not affect the pain threshold of mechanical stimulation. with dose dependent manner. 2. In order to investigate the analgesic effects of BV depending upon different intensities of laser stimulation, the experimental animals were divided into three groups: 3 mW treated group, 6 mW treated group and 10 mW treated group. The low power GaAsAl laser stimulation was applied into zusanli acupoint for 30 min with different intensity of laser stimulation. Six and ten mW of laser stimulation significantly increased the pain threshold of mechanical stimulation at 15 min after laser stimulation as compared to that of control group(P<.05). Moreover, the analgesic effect of 10 mW laser stimulation was maintained for 30 min after laser stimulation (P<.05). 3. Finally, we tested the analgesic effect of 10 mW laser stimulation using different duration such as 10 min, 30 min or 1 hr after application of mechanical stimulation. In 30 min treatment group, the pain threshold of mechanical stimulation was increased at 15min and 30min after laser stimulation(P<.05). However, laser stimulation for 60 min dramatically increased the pain threshold of mechanical stimulation at 0 min after laser stimulation and the analgesic effect of laser stimulation was observed until 1 hr after laser stimulation. In conclusion, these data apparently demonstrate that low power GaAsAl laser has analgesic effect on mechanical induced pain model in rats. In addition, the treated point, intensity and duration of laser stimulation should be concerned before clinical application for pain management purpose.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2012.05a
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• pp.861-862
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• 2012

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2008.06a
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• pp.391-392
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• 2008

• Bulletin of the Korean Chemical Society
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• v.35 no.11
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• pp.3294-3298
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• 2014

We theoretically investigated the coherent control of Autler-Townes splitting in photoelectron spectroscopy of K2 molecule within an ultrafast laser pulse by solving the time-dependent Schrodinger equation using a quantum wave packet method. It was theoretically shown that we can manipulate the splitting of photoelectron spectroscopy by altering the laser intensity. Furthermore, it was found that the percentages of each peak in photoelectron spectroscopy can be controlled by changing the envelope of the laser pulse.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2003.06a
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• pp.640-643
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• 2003

We present investigations of the surface micromachining for transparent glass substrate, e.g. soda lime glass using tightly focused 800nm Ti:sapphire femtosecond laser. In this study, experiment conditions such as laser intensity, scanning speed, focus position were controlled as variable parameters to decide optimal machining conditions. This study shows clearly that laser intensity and scanning speed are dominant factors for good surface morphology. Using the optimal conditions, grooves with 50${\mu}{\textrm}{m}$ line width were fabricated on glass substrate and their surface morphologies were investigated from SEM image.

• Journal of the Optical Society of Korea
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• v.11 no.1
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• pp.34-39
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• 2007

Laser-induced breakdown of colloidal suspensions, such as polystyrene, $ZrO_2$, and $SiO_2$ particles in diameters of 100-400 nm in water is investigated by nanosecond flash-pumped Nd:YAG laser pulses operating at a wavelength ${\lambda}$= 532 nm. The breakdown threshold intensity is examined in terms of breakdown probability as a function of laser pulse energy. The threshold intensity for $SiO_2$ particles ($1.27{\times}10^{11}\;W/cm^2$) with a size of 100 nm is higher than those for polystyrene and $ZrO_2$ particles with the same size, namely $5.7{\times}10^{10}$ and $5.5{\times}10^{10}\;W/cm^2$, respectively. Results indicate that the absorption of five photons is required to induce ionization of $SiO_2$ particles, whereas the other particles necessitate four-photon absorption. These breakdown thresholds are compared with those measured by nanosecond pulses from a diode-pumped Nd:YAG laser having a different focusing geometry.

• Current Optics and Photonics
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• v.8 no.4
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• pp.355-365
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• 2024

Wavefront coding (WFC) imaging systems can redistribute the energy of an interference laser spot on an image plane sensor by wavefront phase modulation and reduce the peak intensity, realizing laser protection while maintaining imaging functionality by leveraging algorithmic post-processing. In this paper, a spiral axicon WFC imaging system is proposed, and the performance for laser protection is investigated by constructing a laser transmission model. An Airy disk on an image plane sensor is refactored into a symmetrical hollow ring by a spiral axicon phase mask, and the maximum intensity can be reduced to lower than 1% and single-pixel power to 1.2%. The spiral axicon phase mask exhibits strong robustness to the position of the interference laser source and can effectively reduce the risk of sensor damage for an almost arbitrary lase propagation distance. Moreover, we revealed that there is a sensor hazard distance for both conventional and WFC imaging systems where the maximum single-pixel power reaches a peak value under irradiation of a power-fixed laser source. Our findings can offer guidance for the anti-laser reinforcement design of photoelectric imaging systems, thereby enhancing the adaptability of imaging systems in a complex laser environment. The laser blinding-resistant imaging system has potential applications in security monitoring, autonomous driving, and intense-laser-pulse experiments.

• Physical Therapy Korea
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• v.10 no.2
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• pp.61-70
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• 2003

The purposes of this study was to evaluate the effect of low power GaAsAl laser on tissue contraction in a linear incision wound on rat skin. The linear incision wound was made on the midline of the backside in the experimental animals. Low power laser applications with different intensities such as 3, 6, or 10 mW were applied to the experimental animals twice a day for 10 days. On either the seventh or tenth postoperative day, the quantitative analysis of the inflammatory reaction surrounding the linear incision wounds on the rats were performed using enzymatical analysis of myeloperoxidase (MPO) activity. The number of neutrophil was $.07-1.0{\times}106/m{\ell}$ from a normal blood sample that was obtained from the normal experimental animals. Each concentration of neutrophil showed .04-.62 unit activity of MPO. Therefore, the 6 unit activity of MPO per neutrophil was $.57{\pm}.014{\times}10^{-6}$ unit. On the 7th and 10th post operative day, non treated tissues demonstrated increased MPO activity as compared to that of normal tissue. These data indicated that the inflammatory reaction of tissue was induced after wound induction and the MPO activity were increased in the inflammed tissues. While both 3 mW or 6 mW intensity of laser treatments did not affect the tissue MPO activity, 10 mW intensity of laser treatment significantly decreased the tissue MPO activity on the 7th and 10th post operative day. These data demonstrated that only 10 mW intensity of laser treatment successfully suppressed tissue inflammatory reaction after wound induction. In conclusion, these findings suggested that 10 mW of GaAIAs laser treatments effectively suppressed the inflammatory reaction of tissue that was induced during the wound healing process.

• Korean Journal of Optics and Photonics
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• v.12 no.3
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• pp.177-183
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• 2001

The KrF laser was employed to study NO fluorescence in lean-bum as well as in soot-bum flames. Blue-shifted NO fluorescence was observed in both of the flames. For both of the flames, the fluorescence intensity of NO and its relative background noise signal were measured with respect to the concentration of seeded NO molecule in the flame and the laser intensity. The results were analyzed qualitatively. Also, NO concentration distribution in the lean-bum flame was qualitatively determined from the intensity of the NO fluorescence. cence.