Alps Electric Co., Ltd.

Naoyuki Tokuchi

Yoshihiro Someno

Yuichi Umeda

Shinji Mitsuya

Takuya Nagai

To provide a hologram information recording medium and a hologram information recording/reproducing device capable of accurately reproducing data multiplexed on the recording medium irrespective of the influence of the external environment and so forth. In one recording areaof a recording medium, a plurality of the same information groups are recorded in substantially the same area with varied multi-parameters, in consideration of the expansion and the contraction of the recording medium. That is, a plurality of data groups A to D are recorded in the one recording areaof the recording medium, with a laser wavelength &#x3bb; varied. Specifically, the data groups A to D are recorded in one recording area as three groups: a data group Gincluding data A, data B, data C, and data D; a data group Gincluding data A, data B, data C, and data D; and a data group Gincluding data A, data B, data C, and data D.

Hologram information recording medium and hologram information recording/reproducing device

When currents are applied to driving coils, electromagnetic forces are generated between the currents and magnetic fluxes passing through gaps, a shaft member is swung in one direction, and a tilt angle of a mirror (controlled object) changes relative to a support center point. Electromotive forces generated in detection coils when the magnetic fluxes pass through the detection coils are given as feedback signals to a control unit. The control unit generates currents on the basis of the feedback signals, and applies the currents to the driving coils. By detecting the velocity of the mirror during swinging with the detection coils, the structure of the actuator can be simplified. Further, the responsivity can be increased, and the tilt angle of the mirror can be detected with high accuracy.

Actuator

A hologram information reproducing device is described which can reproduce information from a recording medium on which hologram information is recorded, and which can be downsized. In one aspect, when light from a light source is emitted, the light is converted into parallel reference light, by a lens of an optical system. A mirror changes the orientation of the reference light so that it is oriented obliquely downward towards a recording medium. More specifically, as viewed from the top, the mirror changes a path of the light from the light source unit by approximately 90 degrees. In addition, as viewed from the side, the mirror changes the path of the light from the light source unit downward by approximately 45 degrees. Since an interference pattern recorded on the recording medium is a Bragg grating, when the reference light illuminates a recording area of the recording medium, a reproduction light is obtained by Bragg diffraction. The reproduction light is reflected by a reflecting layer of the recording medium and is detected by a photodetector

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Miyagi-ken, Japan

Naoyuki Tokuchi