Optical Storage DRAW Noise Cancellation via Beam Splitting
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Solution Overview
Problem
Conventional Optical Pickup Units (OPUs) face challenges in directly reading and verifying data during the write operation due to noise introduced by high-frequency writing strategy pulses, which contaminates the signal and reduces the signal-to-noise ratio, making it difficult to accurately recover written data in real-time.
Innovation Solution
The optical storage system employs a configuration with an optical head and controller that splits a laser beam into a higher power main beam and lower power side beams, allowing for direct read after write (DRAW) by processing signals from both beams to remove noise and adjust DC bias or delay based on signal quality, enabling real-time data verification during the write operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If direct read after write is performed using the higher power main beam, then real-time data verification is achieved, but noise from high-frequency writing strategy pulses contaminates the signal and reduces signal-to-noise ratio
Solution Approach 1:
The optical beam is segmented into multiple lower power beams from a single laser element using a diffraction grating, allowing separate reading and writing operations with reduced interference and improved signal quality
Solution Approach 2:
A diffraction grating is introduced as an intermediary optical element to split the laser beam into multiple beams, enabling the main beam to write data while side beams read verify the data simultaneously with reduced noise contamination
2Device complexity
If a single laser element is used to generate multiple beams for reading and writing, then device complexity is reduced, but beam power distribution and signal quality become more difficult to control
Solution Approach 1:
A single laser element performs multiple functions by generating both the main beam for writing and side beams for reading/verification, reducing overall system complexity while maintaining signal quality through proper power distribution
Solution Approach 2:
Different regions of the optical system receive different beam powers optimized for their specific functions - the main beam receives higher power for writing while side beams receive lower power for reading, achieving optimal performance for each function
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 effectively cancels out noise and improves signal quality, allowing for accurate data recovery and verification during the write process with a high signal-to-noise ratio, enabling fast and reliable data verification in real-time, even for multiple channels.
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
a second signal resulting from scatter of the higher power main beam
Implementation Method 3
a first signal resulting from a lower power side beam being reflected from the medium
Data Source
AI summary
An optical storage system includes an optical head and a controller. The optical head is configured to split a light beam into a higher power main beam and a lower power side beam. The controller is configured to write data to an optical medium via the higher power main beam, and read, directly after writing, feedback from the optical medium containing the written data and noise caused by the higher power main beam. The controller is also configured to process the feedback using data indicative of the higher power main beam to remove the noise and generate output indicative of the written data, and automatically adjust a delay of the feedback or the data indicative of the higher power main beam based on a signal quality of the output.