Abstract: A head-up display device projects a virtual image. The head-up display device includes a display, a first optical member, a second optical member, and an adjuster. The display outputs light that becomes a display image corresponding to the virtual image. The first optical member reflects the light incident from the display. The second optical member reflects or transmits the light reflected by the first optical member such that the virtual image is projected. The adjuster moves the first optical member to adjust a projection distance of the virtual image. The adjuster changes a distance between the first optical member and the second optical member and an inclination angle of the first optical member with respect to the display according to the projection distance of the virtual image.

Abstract: A head-up display device projects a virtual image. The head-up display device includes a display, a first optical member, a second optical member, and an adjuster. The display outputs light that becomes a display image corresponding to the virtual image. The first optical member reflects the light incident from the display. The second optical member reflects or transmits the light reflected by the first optical member such that the virtual image is projected. The adjuster moves the first optical member to adjust a projection distance of the virtual image. The adjuster changes a distance between the first optical member and the second optical member and an inclination angle of the first optical member with respect to the display according to the projection distance of the virtual image.

Abstract: In an optical head, a light emitting element emits an optical beam, and the beam is condensed by a condensing element onto an information recording medium. A first plate beam-splitting element has a splitting ratio of P polarization to S polarization, and it splits at least a part of the beam reflected by the information recording medium along a direction different from that of a direction returning to the light emitting element. A second plate beam-splitting element is provided in parallel to the first plate beam-splitting element, and it splits the beam split by the first plate beam-splitting element into at least two beams having polarization planes perpendicular to each other. The two beams are detected by a pair of photosensors.

Abstract: The relative tilt of an optical disk and a movable objective lens holder is measured as an output of a differential amplifier which subtracts an output of first photodetectors and which detect the reflected light from optical disk from an output of second photodetectors and which detect the reflected light from a reflector mounted on movable objective lens holder. The signal from differential amplifier is used to tilt movable objective lens holder so that the movable objective lens holder compensates the tilt of optical disk.