Experimental Investigations on Wavefront Distortion of LD-Pumped Neodymium-Doped Silica-Glass Rod with High Thermal Shock Parameter

The characterization of a laser diode (LD)-pumped neodymium-doped silica glass (NDSG) laser is here described. The gain performance and wavefront distortion were measured, and the thermal toughness and uniformity distribution of the material were experimentally observed. At a pumping frequency of 1 Hz and energy 7.79 J, a small-signal gain of 1.16 was measured, and the wavefront distortion reached 2.67 λ (wavelength λ = 1053 nm). At a pumping frequency of 25 Hz with 194 W power, the NDSG was still not cracked, which is consistent with its high thermal shock parameter. However, the material uniformity was relatively poor. These results indicate good prospects for the application of NDSG lasers at high energy and high repetition frequency, but the gain performance, uniformity, and other aspects affected by the manufacturing process need to be improved.

A Method to Evaluate Mixture Segregation Based on Space Grid of Image Processing Technology

A space grid method, based on image processing technology, was proposed to evaluate asphalt mixture segregation, which used the ratio of statistical data variance and its square of mathematical expectation to describe material uniformity by statistics of distribution of particles on space grid. Computer procedure was developed and some experiments are made. The results indicate that this method is simple and can be used to evaluate asphalt mixture uniformity quantitatively with a good adaptability.

A DC Comparison Study between H-Intercalated and Native Epi-Graphenes on SiC Substrates

The aim of this study is to compare DC characteristics of ‘as-grown’ and hydrogen (H)-intercalated epitaxial graphenes on SiC substrates [1,2]. Epitaxial graphene is grown on SiC at 1400-1600C, and H-intercalation is performed via in-situ introduction of Hydrogen during the graphitization process [6]. The fabrication processing steps used to define test structures are identical for the two materials. Results on the DC behaviour and uniformity issues with respect to both materials are reported. As-grown material behaves as a linear resistance, while H-intercalated demonstrates a non-linear characteristic. Hysteresis effects and time dependent behaviors are also observed in both materials. Extensive Hall measurements are performed on both materials with the aim of providing a qualitative understanding of material uniformity in both epi-graphenes.