Radial Servo Device for Super-Resolution Optical Discs
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Solution Overview
Problem
Traditional optical disc servo control systems struggle to accurately perform radial tracking servo for super-resolution optical discs due to the limitations imposed by the optical diffraction limit, which restricts the size of recording points, making it difficult to achieve high-density storage and increasing costs with existing technologies.
Innovation Solution
A radial servo device and method that utilizes an integrated optical path with excitation and servo light sources, a focusing unit, and a drive control unit to accurately control the position of data tracks on a super-resolution optical disc with a multi-layer structure, enabling radial tracking servo without changing the wavelength or groove width, using technologies like super-resolution fluorescence microscopy and two-photon absorption to break the diffraction limit.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional reflection-based servo control methods are used, then the system structure is simple, but the radial tracking servo precision deteriorates due to the optical diffraction limit
Solution Approach 1:
The patent combines the excitation light path and servo light path into a single integrated optical system. The excitation light focuses on the data recording layer to read data, while the servo light focuses on the servo guide layer to generate tracking error signals. Both light paths share the same objective lens and optical components, merging two functions into one unified system to achieve high-precision radial tracking without requiring separate complex servo mechanisms
Solution Approach 2:
The patent introduces a servo guide layer with spiral grooves as an intermediary structure between the data recording layer and the detection system. This servo guide layer reflects servo light to generate tracking error signals that indicate radial position deviations. The intermediary servo structure enables precise measurement of radial position without directly measuring the super-resolution recording points themselves
2Measurement precision
If pre-encoded position signals are embedded in track grooves using magneto-optical hybrid servo system, then radial tracking servo can be realized, but manufacturing cost increases dramatically
Solution Approach 1:
The patent replaces expensive magneto-optical hybrid servo systems with a simpler, more cost-effective approach using conventional optical reflection. Instead of requiring complex magnetic field embedding and magneto-optical materials in each recording layer, the invention uses a dedicated servo guide layer with standard reflective properties that can be manufactured using conventional optical disc manufacturing processes, dramatically reducing production costs while maintaining servo functionality
3Measurement precision
If the size of pre-groove is reduced to match super-resolution recording points, then tracking precision improves, but the optical diffraction limit prevents effective servo control
Solution Approach 1:
The patent segments the optical disc structure into two distinct functional layers: a data recording layer with super-resolution recording points and a separate servo guide layer with spiral grooves. The servo guide layer contains dedicated tracking information with groove dimensions optimized for servo control, while the data layer maintains ultra-fine recording density. This segmentation allows each layer to be optimized independently for its specific function
4Measurement precision
If fluorescence quantum dots are used for tracking, then radial tracking servo may be achieved, but current semiconductor development technology creates obstacles
Solution Approach 1:
The patent enables the servo guide layer to generate its own tracking error signals through passive optical reflection of servo light from the spiral groove structure. The groove geometry itself creates the interferometric patterns that provide radial position information, eliminating the need for external quantum dots, fluorescent markers, or other active materials that would require complex semiconductor fabrication processes
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 solution allows for radial tracking servo control with signal tracks narrower than 100 nm, significantly improving storage density, reducing costs, and enabling multi-layer ultra-high density data storage without the need for servo markers on each recording layer, with nanometer-level precision and compatibility with other servo controls.
Implementation Method 1
super-resolution fluorescence microscopy
Implementation Method 2
optical diffraction limit effect
Implementation Method 3
reflected light is detected by the servo light detection unit
Implementation Method 4
focused on the disc surface
Implementation Method 5
two-photon absorption technology
Data Source
AI summary
A radial servo control device for a super-resolution optical disc includes an excitation light source, a servo light source, an integrated optical path, focusing units, a servo light detecting unit and a drive control unit; the drive control unit presets N detection error reference values with respect to each guide layer trench irradiated by servo light, and controls corresponding positions of the focusing units in N data tracks below each guide layer trench according to a comparison result between a detection result of servo reflected light and the detection error reference values. The device is applicable to a variety of super-resolution optical discs on the basis of stimulated radiation loss microscopy technology, a two-photon absorption technology, and the like, and achieves accurate radial servo control of super-resolution data tracks (<100 nm) without reducing the wavelength of servo light and the width of guide layer trenches.