Patent ID: 8130625
Filing Date: 2012-03-06
Classification: G11B

Abstract:
1. An optical information recorder and reproducer that records information on and reproduces information from an optical information recording medium having an information layer using near field light, comprising: a condensing member for generating the near field light; a distance detection section that detects a distance between the condensing member and the optical information recording medium using return light from a region where the near field light is generated; a distance control section that controls the distance between the condensing member and the optical information recording medium; a focus position changing member that changes a focus position of the near field light on the optical information recording medium; a focus detection section that detects a state of focus on the information layer using reflection light from the information layer; a focus position adjusting section that adjusts a position of the focus position changing member; a focus control section that controls the focus position changing member such that the near field light is focused on the information layer; and a switching section that selects the focus position adjusting section or the focus control section to adjust the focus position of the near field light on the optical information recording medium, wherein the focus position adjusting section adjusts the position of the focus position changing member such that the near field light is not focused on the information layer until the distance control section initiates control to keep the distance between the condensing member and the optical information recording medium constant, the distance control section controls the distance between the condensing member and the optical information recording medium to be constant based on the detection result of the distance detection section, the focus position adjusting section adjusts the position of the focus position changing member such that the near field light is focused on the information layer with the distance between the condensing member and the optical information recording medium controlled to be constant, the switching section switches a focus position adjustment by the focus position adjusting section to a focus control by the focus control section at a timing at which the focus position of the near field light is aligned with the position of the information layer, and the focus detection section detects the focused state and the focus control section controls the focus position changing member such that the near field light is focused on the information layer based on the detection result of the focused state with the distance between the condensing member and the optical information recording medium controlled to be constant.