Invention Grant
US08238223B2 Deformable mirror, optical head, and optical recording and playback device 失效
变形镜,光头,光记录播放装置

Deformable mirror, optical head, and optical recording and playback device
Abstract:
For a recording and playback optical head used for a dual layer disc, it is difficult to reduce the size and the cost due to the need to correct spherical aberration caused by a difference in thickness of a light-transmitting layer.A reflection mirror having a reflection surface on which light is reflected and provided with a member having ferromagnetism at the center, and a switching device that switches between a deformed state and a non-deformed state of the reflection mirror using a magnetic force are provided. The switching device includes a hard magnetic member, and a magnetizing member that magnetizes and demagnetizes the hard magnetic member. When light is concentrated on a first recording layer farther from the light-incident surface, the reflection mirror is used as a plane mirror, and when light is concentrated on a second recording layer closer to the light-incident surface, the reflection mirror is deformed in the shape of a concave surface by means of the switching device.
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