In recent years, we have known that LED becomes a reliable source of a projection system due to its flux enhancement, high pure color and the compact size. In this paper, we will discuss a new simple single micro‐display projection system with a high efficiency collimator in it. Due to the LED is emitting to the semi‐sphere space, the collimator is specially designed for its emitting properties. With the novel collimator, a prototype of LED projection display is finished and has over 50% optical system efficiency in it.

Parameter analysis for laser welding, optical measurement tests and tension shear tests are conducted on materials for fuel cell stack bipolar plates, and seven groups of welding parameters are chosen and tested. The optical measurement tests reveal that at the same power and duration time, specimens 1 (20 PPR, 5 mm/s) and 4 (50 PPR, 10 mm/s) obtained greater welding quality with proper welding frequency and velocity. The tension shear tests demonstrate that the bonding strength of both specimen 1 and 4 exceeded 0.4 MPa, the result of which are proper applied to high power fuel cell systems. A new fuel cell stack structure is subsequently designed for this high strength and accuracy modular sealing technique.