Backlighting for backlighting of a display unit for a head-up display, head-up display and method of backlighting a display unit for a head-up display

The invention relates to a backlighting device (400) for backlighting of a display unit (402) for a head-up display (100). The backlighting device (400) comprises at least one light source (404) for emitting a light beam (406) and at least one between the light source (404) and the display unit (402) or can be arranged aperture (408) having at least one aperture (410) for generating a jet cone (412) with a predetermined width by using the light beam (406). Here, the aperture (408) and / or the aperture (410) in at least one direction is movable to change an incident angle of the jet cone (412) on the display unit (402).