LiF: F(2)- as a high repetition rate Ng: YAG laser passive modulator.
30-pps 30-mJ 10-ns FWHM pulses have been obtained in Nd:YAG laser systems with LiF crystal containing F(2)- color centers as the passive Q-Switch modulator. The saturation level of F(2)- color centers in the host crystal and the annealing phenomena of LiF: F(2)-(2) crystal were investigated. These observations make this room temperature stable color center crystal superb as a high power, high repetition rate neodymium laser passive modulator.
Solid-state Laser Rangefinders
Describes the development of solid-state laser rangefinders, during the last thirty years. The laser rangefinders using solid-st3te laser materials operating in visible, near and mid.infrared spectrum of light are in use. Considering the cost, efficiency, atmospheric transmission and detection capability, neodymium laser rengefinders. operating in near-infrared region are still the state-of-the-art and are more in use as compared to rangefinders using other solid-state materials. The neodymium laser rangefinders in different configurations and use, developed in this Establishment are also described. The neodymium and diode lasers with improved detection capability in multiple pulse operation with pulse correlation techniques are under development to make these rangefinders eyesafe.
EFFECT OF SAMPLE PREPARATION ON WATER TREE RESISTANCE OF XLPE/SEBS BLENDS
The effects of an aromatic polymer, such as poly[styrene-b-(ethylene-co-butylene)b-styrene] (SEBS), and its preparation processes on water tree resistance, morphology, crystallinity, dielectric constant and dielectric loss tangent of crosslinked polyethylene (XLPE)/SEBS and XLPE/SEBS/ethylene vinyl acetate (EVA) blends were investigated. The XLPE/SEBS samples were characterized by means of differential scanning calorimetry, scanning electron microscopy, dielectric spectral analysis and the accelerated water treeing experiment. The results clearly showed that although SEBS was partially compatible with LDPE and it was dispersed evenly in XLPE matrix, the blends demonstrated excellent dielectric performances, such as dielectric constant and dissipation factor. The crystallinity of XLPE/SEBS blends was decreased with increase in SEBS content and it was further decreased with the addition of EVA. SEBS could effectively improve the water-tree resistance of XLPE and both SEBS and EVA were found to improve the water tree resistance of XLPE synergistically as expected. The differences in sample preparation processes could change the phase morphology and dielectric performance of the blends, and could also influence the dispersion of SEBS in XLPE matrix as well as the crystallinity of the blends. Different preparation processes led to different water tree resistance behaviours of the samples. The improvement of SEBS dispersion in XLPE matrix helped to improve the water tree resistance of XLPE.