Optical writing device
To provide an optical writing device that outputs image light to be recorded to a display recording medium. An optical element thereof includes a two-dimensional periodic structural body including periodic structure sections sectioned along a direction orthogonal to the direction along which transparent layers and light absorption layers are arranged alternately in a repeated manner. At least a part of the periodic structure sections is in a periodic structure in which the transparent layers and the light absorption layers are arranged alternately by varying phases of spatial frequencies of the transparent layers neighboring in the orthogonal direction. Repeated period pitches of the transparent layers and the light absorption layers in the two orthogonal directions of the two-dimensional periodic structural body are set to match with each other, and the repeated period pitches are set to be narrower than a layout pitch of the pixels of the spatial light modulating element.
1. An optical writing device which outputs image light to be recorded to a display recording medium, comprising
a spatial light modulating element in which a plurality of pixels that spatially modulate image forming light emitted from a surface-type light source section into the image light are arranged in matrix within a plane, and
an optical element which allows the image light to make incident on the display recording medium by restricting an emission angle range of the image light emitted from the spatial light modulating element, wherein:
the optical element includes a two-dimensional periodic structural body in which transparent layers that transmit the image light and light absorption layers that restrict a range of emitted directions of the image light that transmits through the transparent layer are alternately arranged within the plane in a repeated manner;
the two-dimensional periodic structural body includes a plurality of periodic structure sections along a direction that is orthogonal to the direction along which the transparent layers and the light absorption layers are arranged alternately in a repeated manner;
at least a part of the plurality of periodic structure sections is in a periodic structure in which the transparent layers and the light absorption layers are arranged alternately in a repeated manner by varying phases of spatial frequencies of the transparent layers that are neighboring to each other in the orthogonal direction; and
repeated period pitches of the transparent layers and the light absorption layers in the two orthogonal directions of the two-dimensional periodic structural body are set to match with each other, and the repeated period pitches are set to be narrower than a layout pitch of the pixels of the spatial light modulating element.
2. The optical writing device as claimed in claim 1 , wherein
at least a part of the plurality of periodic structure sections includes a periodic structure in which the transparent layers and the light absorption layers are arranged alternately in a repeated manner by varying the phases of the spatial frequencies of the transparent layers by 180 degrees.
3. The optical writing device as claimed in claim 1 , wherein
the repeated period pitches are set to be an integral submultiple of a period pitch at which the pixels are arranged within the plane of the spatial light modulating element.
4. The optical writing device as claimed in claim 1 , wherein
each of the plurality of pixels of the spatial light modulating element forms a rectangular shape with short sides and long sides, and the plurality of pixels are arranged in a grid-like pattern in an orderly manner within the plane.
5. The optical writing device as claimed in claim 1 , wherein
each of the plurality of pixels of the spatial light modulating element forms a square shape, and the plurality of pixels are arranged by varying the phase of the spatial frequencies of the pixels that are neighboring to each other in the orthogonal direction within the plane.
6. The optical writing device as claimed in claim 5 , wherein
the phases of the spatial frequencies of the neighboring pixels are set to be different by 180 degrees.
7. An optical writing device which outputs image light to be recorded to a display recording medium, comprising
a spatial light modulating element in which a plurality of pixels that spatially modulate image forming light emitted from a surface-type light source section into the image light are arranged in matrix within a plane, and
optical means for allowing the image light to make incident on the display recording medium by restricting an emission angle range of the image light emitted from the spatial light modulating element, wherein:
the optical element includes a two-dimensional periodic structural body in which transparent layers that transmit the image light and light absorption layers that restrict a range of emitted directions of the image light that transmits through the transparent layer are alternately arranged within the plane in a repeated manner;
the two-dimensional periodic structural body includes a plurality of periodic structure sections along a direction that is orthogonal to the direction along which the transparent layers and the light absorption layers are arranged alternately in a repeated manner;
at least a part of the plurality of periodic structure sections is in a periodic structure in which the transparent layers and the light absorption layers are arranged alternately in a repeated manner by varying phases of spatial frequencies of the transparent layers that are neighboring to each other in the orthogonal direction; and
repeated period pitches of the transparent layers and the light absorption layers in the two orthogonal directions of the two-dimensional periodic structural body are set to match with each other, and the repeated period pitches are set to be narrower than a layout pitch of the pixels of the spatial light modulating element.