Spatio-temporal coupling of RMS errors in laser amplification.

We developed a theoretical model for the relationship between the input and amplified laser beams of energy stability and spatial uniformity in the amplification process. 10 Hz, 8 ns, 1064 nm Nd:YAG Q-switched resonator with Nd:YAG main amplifier was employed for the experiment. The theoretical model simulation and Frantz-Nodvik simulation were performed by utilizing the obtained beam image, acquired energy from the experiment, and stored fluence from the gain medium. The result indicated that the fluctuation of the spatial distribution in a single beam influences the stability of temporally distributed energy during the amplification process of the laser beam, thereby improving energy stability.

Simultaneous Measurement of Group Refractive Index Dispersion and Thickness of Fused Silica Using a Scanning White Light Interferometer.

In this study, we simultaneously measured the group refractive index dispersion and thickness of fused silica using a scanning white light interferometer on a spectral range from 800 to 1050 nm. A delay error correction was performed using a He-Ne laser. The accuracy of the measured group refractive index dispersion of fused silica, when compared to the temperature-dependent Sellmeier equation, is within 4 × 10-5.

Performance of zoom homogenizer to control the size of illumination field.

We performed an illumination simulation, wave-optical simulation, and experiment on a zoom homogenizer and conventional beam homogenizer. The wave-optical simulation was performed for each lenslet using the shifted angular spectrum method for effective memory use. In the experiment, the parameters of the zoom homogenizer and beam homogenizer at all zoom positions were set using a system matrix. The uniformity and peak effect of the beam homogenizer were 16.57% and 16.63%, respectively, but those of the zoom homogenizer were 7.15% and 1.46%, respectively. The illumination field generated by the zoom homogenizer had a higher uniformity and lower peak effect at all zoom positions than the conventional one.

Clinical efficacy of herbal extract cream on the skin hydration, elasticity, thickness, and dermis density for aged skin: A randomized controlled double-blind study.

BACKGROUND: Traditional medicine herbal prescriptions used for the treatment of skin disease have been developed into cosmetics. Sang-Hyul-Yun-Boo-Em (SHYBE) is a mixed herbal formula prescribed for patients with yin or blood deficiency patterns of skin disease. A previous study reported that SHYBE exercises anti-allergic and anti-inflammatory effects. To date, no study has reported the efficacy of cosmetics containing the SHYBE extract. AIMS: To observe the efficacy of SHYBE extract cream on hydration, elasticity, thickness, and dermis density in aged skin. METHODS: This was a double-blind randomized placebo-controlled parallel-group trial. The trial consisted of an 8-week topical application of the test or placebo products with two visits at 4-week intervals. A total of 46 healthy Korean females, aged 40-59, were enrolled in this study. Objective skin assessments for hydration, elasticity, thickness and dermis density, self-assessment, and safety assessment were conducted. RESULTS: Sang-Hyul-Yun-Boo-Em extract cream improved skin hydration, elasticity, and dermal density in Asian middle-aged females compared with placebo cream, which excluded SHYBE extract and contained other cosmetic materials. CONCLUSIONS: Sang-Hyul-Yun-Boo-Em extract cream showed anti-aging properties in middle-aged women. It could be recommended for aging skin with dryness, and loss of elasticity and density.

Design of square-shaped beam homogenizer for petawatt-class Ti:sapphire amplifier.

We have designed a square-shaped beam homogenizer using a lens array for pumping a petawatt-class Ti:sapphire amplifier. The designed beam homogenizer generated a flat-top uniform square pump beam with 5.1% of edge steepness and 2.7% of RMS spatial uniformity, respectively. This pump beam generated an output beam with 74 J of energy and 56.8% of extraction efficiency, respectively. A scalar diffraction and two-dimensional amplification simulation were performed for optimization. The results indicate the possibility of improving an amplification efficiency and developing a compact square petawatt-class laser system.