Optical Head Cylindrical Lens Integration
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Solution Overview
Problem
Conventional optical heads face challenges in achieving small size and improving signal characteristics for recording and reproduction on high-density multilayer optical disks due to relative positional errors between the cylindrical lens and light detector, leading to deterioration in tracking error signals and recording/reproduction performance.
Innovation Solution
An optical head design where the cylindrical lens and light detector are integrated with a holder, with the cylindrical lens bonded to one main face and the light detector to the other, allowing precise adjustment and reducing relative positional errors, thus enhancing signal quality and system stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the cylindrical lens and light detector are separated and adjusted independently, then the position can be adjusted for signal balance, but the relative positional error increases and device complexity increases
Solution Approach 1:
The patent integrates the cylindrical lens and light detector onto a single common holder, making them move as one unit. This eliminates the relative positional error that occurs when they are adjusted independently, while still allowing the entire assembly to be positioned for optimal signal balance. The integration ensures that both components maintain their relative positions during adjustment and operation.
2Measurement precision
If the cylindrical lens and light detector are adjusted independently, then initial signal balance can be achieved, but the structure becomes more complex and stability decreases
Solution Approach 1:
By combining the cylindrical lens and light detector on a common holder, the patent reduces the number of independent adjustment mechanisms needed. The entire assembly is adjusted as one unit to achieve signal balance, simplifying the adjustment process while maintaining the ability to optimize focus error signal balance.
Solution Approach 2:
Instead of adjusting the cylindrical lens and light detector independently to achieve signal balance, the patent inverts the approach by adjusting their common holder as a unified assembly. This reversal of the adjustment strategy reduces mechanical complexity while achieving the same signal optimization goal.
3Volume of moving object
If the cylindrical lens is positioned closer to the light detector, then the optical head size is reduced, but the relative positional error increases causing signal deterioration
Solution Approach 1:
The patent enables closer positioning of the cylindrical lens and light detector by integrating them on a common holder, which reduces the optical head size. The integration ensures that even at this closer distance, the relative positional error remains minimal because both components move together as one unit, thereby maintaining tracking error signal quality.
4Measurement precision
If independent adjustment of cylindrical lens and light detector is performed, then initial positioning can be optimized, but positional stability during operation decreases
Solution Approach 1:
The patent integrates the cylindrical lens and light detector on a common holder, ensuring they maintain a fixed relative position during operation. The entire assembly can be initially positioned for optimal signal balance, and once positioned, the integrated structure guarantees positional stability because the components cannot drift relative to each other.
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 configuration enables improved focus and tracking error signal balance, stable servo performance, and reduced size of the optical head, supporting high-density multilayer optical disk recording and reproduction with minimized positional offsets and stray light interference.
Implementation Method 1
a cylindrical lens, onto which a reflected light beam that is reflected by the information recording medium is incident, and which generates astigmatism for forming a focus error signal
Implementation Method 2
an objective lens that condenses, in the form of converging light, the light beam emitted by the light source, onto an information recording medium
Data Source
AI summary
An optical head 200 comprises: a light source 101 that emits a light beam; an objective lens 105 that condenses, in the form of converging light, the light beam emitted by the light source 101, onto an information recording medium; a cylindrical lens 115 onto which a reflected light beam that is reflected by the information recording medium is incident, and which generates astigmatism for forming a focus error signal; a light detector 120 that receives the reflected light beam passing through the cylindrical lens 115; and a holder 130 that holds the cylindrical lens 115 and the light detector 120. The holder 130 has a first main face and a second main face that extend in directions that intersect the optical axis of the reflected light beam. The cylindrical lens 115 is bonded to the first main face and the light detector 120 is bonded to the second main face.