摘要:
A method for adjusting at least one alignment control axis of a holographic data storage system or device to or towards a sufficiently optimal recovery position for recovery of a hologram based on a derived feedback error signal and/or a derived feed-forward signal. For the next hologram in the sequence, the derived feedback error signal estimates the direction and magnitude of misalignment of the at least one alignment control axis for one or more previously recovered holograms based on alignment-indicating data. The derived feed-forward signal estimates an optimal alignment value for the at least one alignment control axis for one or more holograms based on recording and recovery operating condition data for the holograms. An iterative alignment procedure may also be used to derive a feedback error signal for one hologram.
摘要:
In one aspect of the present invention, a device for sensing an absolute position of an encoded object, comprising: a position tracking module comprising: a track illumination module configured to illuminate the encoded object with one more light beams, and to detect one or more light beams resulting from said illumination of said encoded object; and an absolute position determinator configured to determine the absolute position of the encoded object based on said one or more light beams resulting from said illumination of said encoded object.
摘要:
A magnetic tape drive dynamically adjusts a transport rate of tape (32) in accordance with a host data rate. The host data rate is assessed in relation to a data fill level of a buffer (116). A controller (130) of the drive compares the data fill level of the buffer with a buffer normalization value and generates an adjustment value for adjusting a signal indicative of the desired linear velocity of the tape. In one embodiment, the controller also dynamically changes the buffer normalization value to reflect e.g., historical performance of the host. In another embodiment the controller adjusts the transport rate when a head (100) is within a predetermined distance of a boundary point whereat the head must change tracks.
摘要:
A holographic device is provided for recovering data in a holographic memory system. The device use homodyne detection to introduce a local oscillator beam into a reconstructed data beam of the recovered hologram. An image of the combined beam comprising the reconstructed data beam and local oscillator beam may be processed to obtain contrast level information for the pixels of the detected image. This contrast level information may then be used to obtain an increased contrast image of the recovered hologram, which may increase the signal to noise ratio (SNR) of the recovered data.
摘要:
In one aspect of the present invention, a device for sensing an absolute position of an encoded object, comprising: a position tracking module comprising: a track illumination module configured to illuminate the encoded object with one more light beams, and to detect one or more light beams resulting from said illumination of said encoded object; and an absolute position determinator configured to determine the absolute position of the encoded object based on said one or more light beams resulting from said illumination of said encoded object.
摘要:
Method and apparatus are provided for re-recording of a frame on magnetic tape (22) when a first recording of the frame is determined to be defective. A frame whose first recording is defective is re-recorded at a spare or reserved location on the tape. The reserved location is dedicated to re-recording of frames, and otherwise cannot have data stored therein. The tape contains a defect map frame (326) which is used to pair physical locations of defective frames with the reserved location whereat the frame is re-recorded. In one embodiment, the reserved location whereat a frame is re-recorded is a reserved physical frame on the same track in which the defective frame is recorded. In another embodiment, the reserved location is on a reserved portion of a track (TG39R) which is not the original track (TG39) upon which the frame is recorded. For embodiments having multi-channel or multi-track frames, the reserved location employs a corresponding plurality of tracks.
摘要:
Methods and systems for equalizing a holographic image page and for compensating nonlinearity of a holographic data storage channel are disclosed. In one embodiment, a method for equalizing a holographic image page includes receiving the holographic image page and dividing the holographic image page into a plurality of local image regions. The method further includes generating a local alignment error vector for each local image region, computing a local finite impulse response kernel for each local image region according to the corresponding local alignment error vector, and adjusting misaligned pixels of each local image region using the corresponding local finite impulse response kernel.
摘要:
A method for adjusting at least one alignment control axis of a holographic data storage system or device to or towards a sufficiently optimal recovery position for recovery of a hologram based on a derived feedback error signal and/or a derived feed-forward signal. For the next hologram in the sequence, the derived feedback error signal estimates the direction and magnitude of misalignment of the at least one alignment control axis for one or more previously recovered holograms based on alignment-indicating data. The derived feed-forward signal estimates an optimal alignment value for the at least one alignment control axis for one or more holograms based on recording and recovery operating condition data for the holograms. An iterative alignment procedure may also be used to derive a feedback error signal for one hologram.
摘要:
A method of recording holograms includes: generating a first signal-beam from a signal-beam source and a first reference beam from a reference-beam source; recording a first hologram in a holographic medium from an interference between the first signal beam and the first reference beam; shifting the reference-beam source after the act of recording the first hologram; generating a second signal beam from the signal-beam source and a second reference beam from the reference-beam source after the act of shifting the reference-beam source following the recording of the first hologram; and recording a second hologram in the holographic medium from an interference between the second signal beam and the second reference beam.
摘要:
A method of writing holograms includes: numbering sections in sequence, where each section has a spatial projection onto a holographic medium; and writing at least one hologram in each of the sections in sequence. Writing in two sections with adjacent spatial projections provides a substantially uniform exposure level for a sequentially subsequent section with a spatial projection that overlaps the two sections.