Optical System

A picture generating unit comprising:

• an optical system comprising (i) a viewing window, (ii) a display device arranged to spatially modulate light in accordance with a first hologram of a first picture displayed thereon to form a holographic wavefront, the optical system being arranged such that a first holographic reconstruction of the first picture is formed substantially on a replay plane, and (iii) an active mask at the replay plane, the active mask comprising an array of optical elements wherein each optical element is arranged to (a) receive a portion of the holographic wavefront from the display device, and (b) be operable between a first optical state and a second optical state wherein, in the first optical state, the optical element is arranged to relay the respective portion of the holographic wavefront to be receivable at the viewing window and, in the second optical state, the optical element is arranged such that the respective portion of the holographic wavefront is not receivable at the viewing window;
• a light source arranged to illuminate the display device of the optical system;
• wherein the first holographic reconstruction comprises first picture content in a first content area and a first artifact of the first picture content formed outside of the first content area in the holographic reconstruction, wherein the first artifact comprises a ghost of the first picture content, and wherein the first artifact is not present in the first picture;
• and
• wherein the optical system further comprises a driver arranged to drive the active mask such that optical elements in correspondence with the first content area of the first holographic reconstruction are driven in the first optical state and at least some optical elements in correspondence with the first artifact are driven in the second optical state.

A head-up display for a vehicle, wherein the head-up display comprises:

• an optical system comprising (i) a viewing window, (ii) a display device arranged to spatially modulate light in accordance with a first hologram of a first picture displayed thereon to form a holographic wavefront, the optical system being arranged such that a first holographic reconstruction of the first picture is formed substantially on a replay plane, and (iii) an active mask at the replay plane, the active mask comprising an array of optical elements wherein each optical element is arranged to (a) receive a portion of the holographic wavefront from the display device, and (b) be operable between a first optical state and a second optical state wherein, in the first optical state, the optical element is arranged to relay the respective portion of the holographic wavefront to be receivable at the viewing window and, in the second optical state, the optical element is arranged such that the respective portion of the holographic wavefront is not receivable at the viewing window;
• wherein the first holographic reconstruction comprises first picture content in a first content area and a first artifact of the first picture content formed outside of the first content area in the holographic reconstruction, wherein the first artifact comprises a ghost of the first picture content, and wherein the first artifact is not present in the first picture;
• and
• wherein the optical system further comprises a driver arranged to drive the active mask such that optical elements in correspondence with the first content area of the first holographic reconstruction are driven in the first optical state and at least some optical elements in correspondence with the first artifact are driven in the second optical state.

A method of holographic image formation that is viewable at a viewing window, wherein the method comprises:

• spatially modulating light in accordance with a first hologram of a first picture displayed on a display device to form a holographic wavefront;
• forming a first holographic reconstruction of the first picture substantially on a replay plane, wherein the holographic reconstruction comprises first picture content in a first content area and a first artifact of the first picture content formed outside of the first content area in the holographic reconstruction, wherein the first artifact comprises a ghost of the first picture content, and wherein the first artifact is not present in the first picture;
• driving an active mask, positioned at the replay plane, in correspondence with the first picture;
• wherein the active mask comprises an array of optical elements, wherein each optical element is arranged to receive a portion of the holographic wavefront;
• wherein driving the active mask comprises driving the optical elements in correspondence with the first content area of the holographic reconstruction in a first optical state and driving at least some optical elements in correspondence with the first artifact in a second optical state;
• and
• wherein, in the first optical state, the optical element is arranged to relay the respective portion of the holographic wavefront to be receivable at the viewing window and, wherein in the second optical state, the optical element is arranged such that the respective portion of the holographic wavefront is not receivable at the viewing window.