Display apparatus for providing an enlarged display area

A method for displaying a virtual image (VIMG1), the method comprising:

• providing a plurality of input light beams (B0P0,R,B0P1,R) of input light (IN1) such that the input light beams (B0P0,R,B0P1,R) correspond to image points (P0, P1) of an input image (IMG0),
• forming output light beams (B3P0,R,B3P1,R) of output light (OUT1) by using an expander device (EPE1) to expand the input light beams (B0P0,R,B0P1,R) of the input light (IN1), and
• causing a rotary motion of the expander device (EPE1),
• the expander device (EPE1) comprising:
• a waveguide plate (SUB1),
• an in-coupling element (DOE1) to form first guided light (B1a) and second guided light (B1c) by coupling input light (IN1) into the waveguide plate (SUB1),
• a first main out-coupling element (DOE3a) to form output light (OUT1) by coupling the first guided light (B1a) out of the waveguide plate (SUB1), and
• a second main out-coupling element (DOE3c) to form output light (OUT1) by coupling the second guided light (B1c) out of the waveguide plate (SUB1), wherein the in-coupling element (DOE1) has a first input grating vector (V1a) and a second input grating vector (V1c),
• wherein the first main out-coupling element (DOE3a) has a first output grating vector (V3a),
• wherein the second main out-coupling element (DOE3c) has a second output grating vector (V3c),
• wherein the sum of the first input grating vector (V1a) and the first output grating vector (V3a) is equal to zero,
• wherein the sum of the second input grating vector (V1c) and the second output grating vector (V3c) is equal to zero,
• wherein positions of diffractive features (F1,F1a,F1c) of the in-coupling element (DOE1) are selected such that an angle (α1ac) between the first input grating vector (V1a) and the second input grating vector (V1c) is in the range of 60° to 120°.