Abstract: A fuel injection device (100) includes a control body (40) provided with an injection hole (44), a nozzle needle (60) that opens or closes the injection hole (44), a pressure control chamber (53) controlling a movement of the nozzle needle (60), an inflow channel (52) through which high-pressure fuel is introduced to the pressure control chamber (53), an outflow channel (54) through which the fuel from the pressure control chamber (53) is discharged, and a floating plate (70) that opens or closes the inflow channel (52).

Abstract: A grating lens is disclosed in which diffraction efficiency varies in the focusing direction of light on a surface of the lens. Also disclosed is a focusing grating coupler in which the diffraction efficiency of a grating formed on an optical waveguide, which is formed on a substrate, varies in the focusing direction of light.

Abstract: An optical element having a substrate and a composite grating pattern formed thereon. The pattern is constituted with two different kinds of grating patterns superimposed on the substrate. When one of the two kinds of grating patterns is formed in a Fresnel lens pattern, a light focusing or collimating function (i.e. a lens function) is implemented. When the other pattern is formed in an equally separated linear grating pattern, the optical element develops the lens function and a function to diffract lights through the linear grating. When one of the two kinds of grating patterns is formed in a Fresnel lens pattern and the other pattern is implemented in an unequally separated linear grating pattern, a lens function to focus lights onto a point and a cylindrical lens function to focus lights in a linear contour are obtained. Consequently, when parallel lights are incident to the optical element, there occurs astigmatism.