Electron beam surface remelting has been carried out on AISI D2 cold-worked die steel. The microstructure and hardening behavior of the electron beam surface remelted AISI D2 cold-worked die steel have been studied by means of optical microscopy and Vickers hardness testing. It was found that AISI D2 steel can be successfully surface hardened by electron beam surface remelting. This surface hardening effect can be attributed to microstructural refinement following electron beam surface remelting.
In traditional optical microsopy the uniformity of off-axis illumination is poor. In this paper we propose a novel LED optical system for near-field illumination in microscopy. The system includes a LED light source, an optical collimator and a freeform, micro-reflective lens array. The Monte Carlo method is used to simulate the system. The simulation results show that the illumination uniformity can be better than 85% in the observation zone. The optical system can be put at the side of the main optical axis of the microscope. The illumination uniformity is not varied when the observation distance changes so it has good stablilty.
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