Abstract: An optical system includes: a light guide to guide image light; a partial reflector; and a reflector. The partial reflector transmits a first image light guided in a first direction from a first side of the partial reflector in a light guide; and reflects second image light to exit outside from a light emission surface of the light guide, the second image light being guided in the light guide in a second direction opposite to the first direction from a second side of the partial reflector. The reflector at the second side of the partial reflector reflects the first image light back to the partial reflector as the second image light in the second direction. A dimension of the light guide in a thickness direction is longer than a beam diameter of the image light guided in the light guide. The light emission surface has a negative power.

Abstract: An optical system for a virtual display device includes: a light guide; a partial reflector to: transmit first image light guided in a first direction from a first side of the partial reflector through the light guide; and reflect second image light to exit outside the light guide, the second image light guided in a second direction, different from the first direction, from a second side different from the first side through the light guide; a reflector at the second side of the partial; and a polarizer. The polarizer rotates a polarization of the first image light polarized in a first polarization direction; and rotates a polarization of the second image light to polarize the second image light in a second polarization direction. The partial reflector has a lower reflectance for light polarized in the first polarization direction than for light polarized in the second polarization direction.

Abstract: A light guide includes: a first light guide portion including: an optical entrance; and multiple reflecting surfaces including at least one first reflecting surface and at least one second reflecting surface, the multiple reflecting surfaces configured to separate a light flux entered through the optical entrance, into multiple light fluxes; and a second light guide portion including an optical exit. The second light guide portion is configured to cause the multiple light fluxes to propagate therethrough and exit from the optical exit. A part of the light flux strikes and reflects off the at least one first reflecting surface to propagate into the second light guide portion. Another part of the light flux strikes and reflects off the at least one second reflecting surface without striking the at least first reflecting surface, to propagate into the second light guide portion.

Abstract: A propagation optical system includes: a first optical system; an intermediate optical element; and a second optical system. The first optical system, the intermediate optical element, and the second optical system being sequentially arranged in a direction from the image display element toward the light guide member along an optical axis. The intermediate optical element has a non-rotationally symmetric curved surface, of which shape is non-rotationally symmetric about the optical axis. A cross-sectional shape, of the non-rotationally symmetric curved surface, in a first plane including the optical axis is non-arc shape. The first plane is a plane in which the non-rotationally symmetric surface has a strongest positive power among planes including the optical axis. The propagation optical system is configured to form, between the first optical system and the second optical system, an intermediate image corresponding to an image displayed on the image display element.