Servo structure in single-bit holographic volume recording and readout

A system for recording micro-holograms on a holographic disk, the system comprising:

• a servo-mechanical system comprising:
• a first actuator configured to actuate a first optical head in one or more of an axial direction and a radial direction with respect to a first side of the holographic disk;
• and
• a second actuator configured to actuate a second optical head in one or more of an axial direction, a radial direction, and a tangential direction with respect to a second side of the holographic disk, wherein the actuation of the second optical head by the second actuator is based on the actuation of the first optical head by the first actuator;
• wherein the first optical head is configured to focus a first beam in a target data position from the first side of the holographic disk and wherein the first optical head is configured to focus a tracking beam on a reference track at the target data position in the holographic disk;
• and
• wherein the second optical head is configured to focus a second beam to interfere with the first beam in the target data position from the second side of the holographic disk, wherein the second side is opposite the first side.

A system for pre-formatting a holographic disk, the system comprising:

• a first optical head configured to:
• focus a first beam to a target data position in the holographic disk;
• focus a tracking beam to a reference track at the target data position in the holographic disk, wherein a reflection of the tracking beam indicates the focus of the first beam on the target data position;
• and
• receive the reflection of the tracking beam from the reference track;
• a second optical head configured to focus a second beam to overlap and interfere with the first beam at the target data position, wherein the second beam is counter-propagating with the first beam;
• a first servo-mechanical system configured to actuate optical components in the first optical head based on the reflection of the tracking beam;
• and
• a second servo-mechanical system configured to actuate optical components in the second optical head based on the transmission of one or more of the first beam and the second beam through the holographic disk.

A method, comprising:

• detecting a first displacement of a focus position of a first beam from an expected data position in a holographic disk, wherein a reflection of a tracking beam from a reference track at the expected data position indicates the focus of the first beam;
• generating first set of error signals indicating the first displacement;
• actuating first optical components in a first optical system in one or more of a radial direction and an axial direction with respect to the holographic disk based on the first set error signals to compensate for the detected first displacement;
• detecting a misalignment between a focus position of a second beam and the focus position of the first beam in a holographic disk;
• generating second set of error signals based on the misalignment;
• and
• actuating second optical components in a second optical system in one or more of a radial direction, an axial direction, and a tangential direction with respect to the holographic disk based on the second set of error signals, to compensate for the detected misalignment.