Optical device and virtual image display device including volume hologram gratings

摘要

An optical device includes: a light guide plate receiving, for each of N types of wavelength bands, a plurality of parallel light beams with different incident angles each corresponding to view angles, and guiding the received parallel light beams; a first and a second volume hologram gratings of reflection type having a diffraction configuration which includes N types of interference fringes each corresponding to the N types of wavelength bands, and diffracting/reflecting the parallel light beams. The optical device satisfies for each wavelength band, a relationship of ‘PL’, where ‘L’ represents a central diffraction wavelength in the first and second volume hologram gratings, defined for a parallel light beam corresponding to a central view angle, and ‘P’ represents a peak wavelength of the parallel light beams.