| 摘要 |
PROBLEM TO BE SOLVED: To provide a display device compact in structure, high in the availability of illumination light and satisfactory in the luminance of display light by controlling each of the incident angle of the illumination light to a hologram and the outgoing angle of the transmitted and diffracted light to a specified range and controlling the halfwidth of the diffraction efficiency of the transmitted and diffracted light to a specified range. SOLUTION: The transmitted and diffracted light by a hologram 9 is made incident on this display device 15, and the reflected light 16 from the device is observed as a display image. The incident angle 12 of the illumination light from a illumination light source 10 for the hologram 9 is controlled to the range from 60 deg. to 80 deg. or from -60 deg. to -80 deg. to the normal line direction of the hologram face, while the emitting angle of the transmitted and diffracted light 14 is controlled to the range from 5 deg. to 30 deg. or from -5 deg. to -30 deg. to the normal line direction of the hologram face. The peak wavelength of the diffraction efficiency of the transmitted and diffracted light 14 from the hologram 9 is controlled to be almost equal to the peak wavelength of the emitted light from the illumination light source 10. The halfwidth of the diffraction efficiency of the transmitted and diffracted light 14 from the hologram 9 is controlled to the range from 10 to 30 nm. |
