Light guide plate for image display

A light guide plate configured for image display, comprising:

• a first resin base;
• a hologram layer formed on one side of the first resin base in a thickness direction:
• an incidence portion formed on another side of the first resin base in a thickness direction, an image light being incident on the incidence portion;
• a display image emission portion formed on the another side of the first resin base at a position separated from the incidence portion in the plane direction which is a direction orthogonal to the thickness direction;
• a second resin base;
• and
• an external light incidence portion is provided on a side of the second resin base opposite to the hologram layer in the thickness direction,
• wherein an arithmetic average roughness Ra of the surface of the first resin base is 2.6 nm or more but 5 nm or less,
• wherein the hologram layer comprises a waveguide diffraction grating portion and a display diffraction grating portion,
• wherein the display image emission portion comprises the display diffraction grating portion and a region of the first resin base facing the display diffraction grating portion in the thickness direction,
• wherein the image light incident on the incidence portion is guided to the display diffraction grating portion through the waveguide diffraction grating portion and emitted to the outside of the light guide plate through the first resin base in the display image emission portion,
• wherein at least a portion of an external light incident on the external light incidence portion is emitted to the outside of the light guide plate through the display image emission portion, and
• wherein a first image on which a second image based on the image light and a third image based on the external light are superimposed is displayed,
• wherein the first resin base has a maximum MC value in a range of from 0.020 to 0.110,
• wherein the MC values are obtained by evaluation using shadow contrast according to Expression (1):
• MC
• =
• Lmax
• -
• Lmin
• Lmax
• +
• Lmin
• ,
• (
• 1
• )
• wherein Lmax is a maximum value of brightness from a brightness distribution, Lmin is a minimum value of the brightness from the brightness distribution, and MC is an evaluated MC value that objectively represents a magnitude of a dip in low brightness portions in the brightness distribution,
• wherein a measurement area of the evaluated MC value is provided at each of 41 points, which are shifted by 2 mm in a lateral direction in a rectangular region having a width of 180 mm in a vertical direction and a width of 80 mm in a horizontal direction,
• wherein a measurement line is selected to divide the measurement area laterally into 40 equal parts in each measurement area, and
• wherein each of the evaluated MC values is measured from the measurement line.