Display system, spatial filter and method

A display system comprising:

• an illumination system configured to emit at least partially coherent light;
• a spatial light modulator, SLM, illuminated by the illumination system and for applying a modulation pattern to illuminating light;
• an optical system arranged to receive the light modulated by the SLM and to produce a Fourier plane of the SLM;
• and
• a spatial filter positioned substantially in the Fourier plane of the SLM;
• wherein:
• the SLM is configured to form a single modulation pattern, H, simultaneously representing at least a first image field occupying a first portion of the Fourier Transform of H, F(H), and a second image field occupying a second, different portion of F(H), and
• the spatial filter is configured such that light corresponding to the first portion of F(H) does not interfere coherently, or interferes partially coherently, with light corresponding to the second portion of F(H).

A display system comprising:

• an illumination system configured to emit at least partially coherent light;
• a spatial light modulator, SLM, illuminated by the illumination system and for applying a modulation pattern to illuminating light;
• an optical system arranged to receive the light modulated by the SLM and to produce a Fourier plane of the SLM;
• and
• a spatial filter positioned substantially in the Fourier plane of the SLM;
• wherein:
• the SLM is configured to form a single modulation pattern, H, simultaneously representing at least a first image field occupying a first portion of the Fourier Transform of H, F(H), and a second image field occupying a second, different portion of F(H);
• and
• the spatial filter comprises:
• first and second shutters that can be switched between a state that allows light to pass and a state that blocks light, the first shutter corresponding to the first portion of F(H) and the second shutter corresponding to the second portion of F(H), wherein in use:
• a single one of the first and second shutters is in the state that allows light to pass at any given time, and
• both the first and second shutters are configured to be in the state that allows light to pass for respective periods within a duration that the SLM is forming the single modulation pattern.

A method comprising:

• determining a first modulation pattern, H1, corresponding to a first image field, wherein the Fourier transform of H1, F(H1) occupies a first portion of the Fourier domain;
• determining a second modulation pattern, H2, corresponding to a second image field, wherein the Fourier transform of H2, F(H2) occupies a second portion of the Fourier domain which is different from the first portion
• displaying H1 and H2 simultaneously via a single modulation pattern on an SLM;
• illuminating the SLM with at least partially coherent light to produce a modulated output;
• and
• filtering the modulated output using a spatial filter substantially positioned in a Fourier plane of the SLM and configured such that light corresponding to F(H1) does not interfere coherently, or interferes partially coherently, with light corresponding to F(H2).

A display system comprising:

• a first illumination system configured to generate a first set of beams of at least partially coherent light;
• a second illumination system configured to generate a second set of beams of at least partially coherent light and spatially offset from the first illumination system;
• a spatial light modulator, SLM, arranged to be illuminated by the first and second sets of beams of light, wherein each of the first and second sets of beams of light are incident on the SLM at a different angle;
• an output optical system arranged to receive light modulated by the SLM;
• a pupil tracking system configured to determine a location of a viewer's pupil;
• and
• a processing system configured to:
• determine at least one active beam of the first and second sets of beams that corresponds to the determined location of the viewer's pupil;
• and
• control the first and second illumination systems so that the at least one active beam is used to illuminate the SLM.