Field lens and display device

A field lens comprising a lens body and an optical structure, wherein:

• the lens body includes at least two layers of gratings;
• along a direction perpendicular to a plane where the lens body is located, the lens body includes a first side and a second side;
• the optical structure is located on a side of at least one grating layer close to the second side;
• the optical structure is used to block at least part of visible light from being incident on one side of the lens body and/or to block at least part of the visible light from being emitted toward the second side of the lens body after being reflected by the gratings;
• along a direction from the first side to the second side, the lens body includes a pre-deflection grating and a converging grating stacked in layers;
• the converging grating includes a plurality of converging sub-gratings stacked in layers and the pre-deflection grating includes a plurality of pre-deflection sub-gratings stacked in layers, the plurality of converging sub-gratings include a first converging sub-grating, a second converging sub-grating, and a third converging sub-grating, the plurality of pre-deflection sub-gratings includes a first pre-deflection sub-grating, a second pre-deflection sub-grating, and a third pre-deflection sub-grating, and along the direction from the first side to the second side of the lens body, light that is able to pass through the lens body and the optical structure includes a first color light ray, a second color light ray, and a third color light ray;
• the first converging sub-grating and the first pre-deflection sub-grating are used to deflect the first color light ray;
• the second converging sub-grating and the second pre-deflection sub-grating are used to deflect the second color light ray;
• and
• the third converging sub-grating and the third pre-deflection sub-grating are used to deflect the third color light ray.

A field lens, comprising a lens body and an optical structure, wherein:

• the lens body includes at least two layers of bulk holographic gratings, each grating layer disposed on a respective substrate;
• along a direction perpendicular to a plane where the lens body is located, the lens body includes a first side and a second side;
• the optical structure is located on a side of at least one grating layer close to the second side;
• a minimal expected diffraction angle at which the lens body diffracts a first color light ray is θ1, wherein θ1 is a minimum angle among angles formed between diffracted first color light and a normal line at which diffraction by the lens body occurs for the first color light ray, and a maximum allowed exit angle at which the optical structure allows the first color light ray to exit is α1, wherein α1<θ1;
• and
• a minimum angle at which the lens body diffracts the first color light ray is A1, wherein α1<A1, such that the optical structure blocks all diffracted first color light emitted toward the second side after reflection by the gratings.