Patent ID: 8223610

Claim:
An information recording medium initialization apparatus for initializing an information recording medium having a recording layer and a reference layer that records information therein through erasing of a preformed initial hologram in the recording layer, comprising: a laser configured to emit an initialization laser beam; a beam splitter configured to split the initialization laser beam into two separate beams; mirrors configured to direct the two separate beams toward opposite sides of the information recording medium; first and second objective lenses configured to focus the two separate beams into two spherical wave recording beams propagating in opposite directions at the same focal point in the information recording medium, forming the initial hologram in the vicinity of the focal point; a focal point moving mechanism configured to sequentially move the focal point along a trajectory at which information is to be recorded later while continuously emitting the two recording beams to form a continuous linear initial hologram; a servo laser configured to emit a servo light beam through the first objective lens to a target track in the reference layer of the information recording medium; a first photodetector configured to convert a servo reflection light beam generated when the servo light beam is reflected by the reference layer into a first received servo light signal; a first servo control circuit configured to move the first objective lens towards or away from the optical information recording medium in response to the first received servo light signal; a second photodetector configured to convert a light beam transmitted through the information recording medium from the second objective lens into a second received servo light signal; and a second servo control circuit configured to move the second objective lens towards or away from the optical information recording medium in response to the second received servo light signal.