Optical Element Saw Teeth Structure Reducing Stray Light
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Solution Overview
Problem
Existing optical elements and optical head apparatuses face challenges in reducing stray light on optical discs, particularly when handling multiple standards like BD, DVD, and CD, leading to performance issues in information storage and retrieval.
Innovation Solution
An optical element with a concave-convex structure featuring different saw teeth shapes on its surface, which provides varying optical path differences for specific wavelengths, effectively reducing stray light by diffusing unwanted light away from the detection path.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a conventional optical element is used to converge light onto optical discs, then light convergence is achieved, but stray light is generated that degrades signal integrity
Solution Approach 1:
The optical element surface is segmented into multiple regions with different concave-convex structures. Each region has specifically designed saw teeth shapes that diffract light to different locations, preventing concentrated stray light formation on the optical disc while maintaining useful light convergence.
Solution Approach 2:
Different regions of the optical element surface are assigned different local optical properties through varying concave-convex structures. The first region has structures optimized for converging light to a first location, while the second region has structures optimized for converging light to a second location, creating location-specific light distribution that eliminates stray light problems.
2Object-affected harmful factors
If the optical element surface is made complex with multiple concave-convex structures, then stray light is reduced, but manufacturing complexity increases
Solution Approach 1:
The harmful stray light effect is extracted and redirected to specific locations away from the optical disc by the second concave-convex structure. This separates the useful light convergence function from the harmful stray light generation, allowing independent optimization of each function.
Solution Approach 2:
The optical element uses discrete parameter variations in the concave-convex structures (different saw teeth shapes and arrangements in different regions) to achieve different light convergence locations. This parameter-based approach provides flexibility in controlling light distribution while maintaining manufacturability through standardized structural elements.
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
The solution significantly decreases the quantity of stray light reflected onto the storage surface, enhancing the performance of information storage, reproduction, and deletion across various optical disc standards by ensuring that light with wavelengths other than the intended does not contribute to the formation of spots, thereby improving signal integrity.
Implementation Method 1
The plurality of different saw teeth shapes respectively give different phase differences corresponding to substantially integer multiples of the wavelength λ1, for light with the wavelength λ1
Data Source
AI summary
An optical element has at least one surface divided into a plurality of regions and includes: a first region configured to converge light with a wavelength λ1 onto a storage surface of a first optical disc and converge light with a wavelength λ2 onto a storage surface of a second optical disc; and a second region formed around the outer circumference of the first region and configured to converge light with the wavelength λ1 onto the storage surface of the first optical disc. The second region has a concave-convex structure concentrically formed on an aspheric surface and having a cross section being a saw teeth shape. The concave-convex structure is formed by a plurality of different saw teeth shapes, and the plurality of different saw teeth shapes respectively give different phase differences corresponding to substantially integer multiples of the wavelength λ1, for light with the wavelength λ1.