Optical Pickup Unit Beam Splitting for Direct Read After Write
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Solution Overview
Problem
Conventional optical storage devices require multiple Optical Pickup Units (OPUs) to achieve Direct Read After Write (DRAW) functionality, increasing cost and complexity, while existing solutions do not effectively reduce noise associated with modulation during data verification.
Innovation Solution
A system and method that splits a light beam into a higher power main beam and lower power side beams to write data and read previously written data simultaneously, using a correlation detector to verify data integrity by correlating the read signal with a time-shifted write signal, thereby reducing noise and achieving DRAW capability with a single OPU.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If multiple independent OPUs are used to provide DRAW functionality, then data verification capability is improved, but device cost and complexity increase
Solution Approach 1:
The patent makes a single OPU perform multiple functions by implementing DRAW capability within one unit. The OPU alternates between writing data with the main beam and verifying the written data with the same beam, eliminating the need for separate read/write heads and reducing system complexity while maintaining verification capability
Solution Approach 2:
The patent combines the write and verify functions into a single OPU unit. By merging the previously separate write head and verify head into one integrated unit, the system reduces the number of components while achieving both data writing and verification capabilities
2Reliability
If multiple independent OPUs are used to provide DRAW functionality, then data verification capability is improved, but device cost increases
Solution Approach 1:
The patent makes a single OPU perform multiple functions by implementing DRAW capability within one unit. The OPU alternates between writing data with the main beam and verifying the written data with the same beam, eliminating the need for separate read/write heads and reducing system complexity while maintaining verification capability
Solution Approach 2:
The patent combines the write and verify functions into a single OPU unit. By merging the previously separate write head and verify head into one integrated unit, the system reduces the number of components while achieving both data writing and verification capabilities
3Device complexity
If a single OPU is used for both writing and reading, then device complexity is reduced, but noise from modulation interferes with data verification
Solution Approach 1:
The patent extracts the verification function from the continuous write process by implementing it as a separate operational phase. The OPU writes data during a first time period, then performs verification during a second time period after the write operation completes, isolating the verification measurement from the harmful modulation noise of the write process
Solution Approach 2:
The patent employs periodic alternation between write and verify operations. The OPU switches between writing mode and verification mode in distinct time periods, allowing the verification to occur when the modulation noise from writing is absent, thus enabling clean signal detection
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Enables direct data verification during writing with reduced noise, providing real-time diagnostic information and improving OPU performance, write strategy, and anticipating anomalies, while maintaining cost-effectiveness by using a single OPU.
Implementation Method 1
an optical pickup unit (OPU) or head having optics that split a coherent light beam into a higher power main beam and at least one lower power side beam
Data Source
Figure 1A~2
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Figure 5A~6
AI summary
Systems and methods for data storage on an optical medium having a plurality of tracks include splitting a light beam into a higher power main beam and at least one lower power side beam that form corresponding spots spaced along a selected one of the plurality of tracks and selectively positioning and aligning the beams/spots along the selected one of the plurality of tracks using the higher power main beam to write data while reading previously written data using the at least one lower power side beam. The systems and methods may include correlating the read signal with a time-shifted write signal to provide a direct read after write capability to verify data written to the optical medium. In one embodiment, an optical tape drive includes an optical pickup unit (OPU) that generates a lower power satellite beam to read data directly after writing by a higher power main beam.