Optical Storage DRAW Noise Cancellation via Signal Division
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Solution Overview
Problem
Conventional optical storage systems face challenges in accurately verifying data during the write operation due to noise interference from high-frequency writing strategy pulses, which affects the quality of direct read after write (DRAW) processes.
Innovation Solution
The implementation of an optical storage system with a controller and optical head that modulates a higher power main beam according to a writing strategy waveform, splits the light beam into a main and side beams, and processes feedback signals to remove noise, enabling direct read after write capability by dividing the read signal by the writing strategy signal to recover and verify the written data.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If high-frequency writing strategy pulses are used to write data to the optical medium, then the writing speed and data storage capability are improved, but noise is introduced into the direct read signal which degrades the verification quality
Solution Approach 1:
The patent converts the harmful high-frequency writing pulses into a useful reference signal for noise cancellation. By using the same writing strategy signal that causes noise as the denominator in a division operation, the system eliminates the noise while preserving the written data signal, thereby improving verification quality without sacrificing writing speed
Solution Approach 2:
The patent introduces a signal processing intermediary (the division operation) between the noisy read signal and the verification result. This intermediary process uses the writing strategy signal as a mediator to cancel out noise components, allowing high-speed writing to proceed while maintaining accurate verification
2Loss of time
If direct read after write is performed to verify data in real-time, then the verification speed is improved, but noise from the writing process contaminates the read signal reducing accuracy
Solution Approach 1:
The patent performs direct read after write to achieve real-time verification, and converts the writing noise from a harmful contaminant into a useful reference. By dividing the read signal by the writing strategy signal, the noise is canceled out, allowing accurate verification to occur immediately after writing without time delay
Solution Approach 2:
The patent uses feedback from the writing process itself (the writing strategy signal) to correct the read signal. The writing signal serves as a reference for noise cancellation, creating a feedback loop that continuously compensates for noise contamination during real-time verification
3Manufacturing precision
If the number of writing pulses is increased to improve write quality, then the manufacturing precision is improved, but the complexity of the writing strategy and signal processing increases
Solution Approach 1:
The patent changes the parameter of pulse frequency in the writing strategy, using high-frequency pulses that are systematically structured. This parameter change improves write quality while the systematic nature of the frequency pattern makes the signal processing (division operation) more effective at canceling noise, rather than increasing complexity
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
This approach enhances the signal-to-noise ratio (SNR) and achieves real-time data verification with improved accuracy, matching the quality of read-back signals by optimizing the number and timing of writing strategy pulses, thereby eliminating distortion and ensuring reliable data verification during the write operation.
Implementation Method 1
Current OPUs may use a diffraction grating or similar optics in the laser path to generate three beams from a single laser element
Implementation Method 2
high-frequency writing strategy pulses in the laser's optical power for creating the crystal phase change on the optical recording layer of the media
Implementation Method 3
the direct read laser power signal from the laser light sensor during the write contains modulation of the written data
Data Source
AI summary
An optical storage system includes an optical head configured to split a light beam into a higher power main beam and at least one lower power side beam. The optical storage system also includes a controller configured to alter an optical medium, via modulation of the higher power main beam according to a writing strategy waveform that defines at least n pulses for every n bits of data to be written to the medium, while processing a first signal resulting from the at least one lower power side beam being reflected from the medium and a second signal indicative of the writing strategy waveform to remove noise from the first signal caused by the higher power main beam to generate output indicative of the data directly after writing.