Abstract: A method of producing a holographic optical element which is capable of imparting complex corrections to the holographic optical element and of effecting the exposure using a short optical path permitting little disturbance to be infiltrated. A correction holographic optical element 13 for correcting the characteristics of the holographic optical element is disposed in at least one of the optical paths of an object beam 35 and a reference beam 36 that fall on a photosensitive material 11. The object beam 35 may be one obtained by reflecting the reference beam 36 by a reflection-type holographic optical element such as a reflection-type master holographic optical element 12. In the case of a holographic optical element used for the head-up display, the correction holographic optical element 13 may be given characteristics for correcting the curvature of the windshield or characteristics for correcting color aberration.

Abstract: A fuel injection device includes an injection hole for injecting fuel therethrough, a needle movable between a first position to open the injection hole and a second position to close the injection hole, and a back-pressure chamber. The fuel injection device further includes a two-way solenoid valve for opening and closing a flow passage between the back-pressure chamber and a drain side so as to change a pressure in the back-pressure chamber. The needle is movable between the first and second positions depending on the pressure in the back-pressure chamber. A first flow restrictor and a second flow restrictor are provided in a flow passage, which introduces high-pressure fuel into the back-pressure chamber, so as to restrict a flow of the high-pressure fuel passing therethrough. The first and second flow restrictors may be arranged in series to each other.