Complex Optical Element for Multi-Layer Disc Aberration Correction
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Solution Overview
Problem
Existing optical pickup systems face challenges in focusing laser lights accurately on multiple information recording faces due to spherical aberration caused by varying distances from the light source, which conventional methods like moving collimator lenses cannot adequately correct, especially for three or more faces.
Innovation Solution
A complex optical element composed of two materials with a diffraction face in the bond area, combined with a movable aberration correction element, allows for precise focusing of laser lights on multiple information recording faces by adjusting the shape of the incident light to correct spherical aberration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single objective lens is used to focus laser lights on multiple information recording faces, then the optical system structure is simple, but spherical aberration occurs due to different distances from the light source side surface to each recording face
Solution Approach 1:
The objective lens is divided into multiple lens units with different refractive indices arranged in sequence along the optical axis. Each lens unit contributes to correcting spherical aberration for different recording faces, enabling the system to focus accurately on multiple faces while maintaining a relatively simple overall structure.
Solution Approach 2:
The patent uses lens units made of different materials (different refractive indices) to construct the objective lens. This composite material approach allows each lens unit to contribute differently to the overall optical correction, enabling effective spherical aberration correction across multiple recording faces.
2Device complexity
If collimator lens movement is used to correct spherical aberration, then the correction mechanism is simple, but the correction is insufficient for three or more information recording faces
Solution Approach 1:
Instead of relying on a single movable collimator lens, the patent segments the correction function into multiple fixed lens units within the objective lens assembly. Each lens unit is optimized to correct spherical aberration for specific recording faces, providing reliable correction for three or more faces without requiring complex movement mechanisms.
Solution Approach 2:
Rather than moving the collimator lens to achieve correction, the patent inverts the approach by incorporating multiple correction lens units directly into the objective lens structure. This stationary multi-unit design achieves the correction effect that would otherwise require dynamic adjustment.
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 enables effective focusing of laser lights on multiple information recording faces, improving the correction of spherical aberration and enhancing the optical pickup's ability to handle various types of optical discs.
Implementation Method 1
a first diffraction face is formed in a region of a bond area between the first optical portion and the second optical portion
Implementation Method 2
an objective lens for focusing the laser lights onto the information recording faces
Data Source
AI summary
A complex optical element includes a first optical portion and a second optical portion which are made of materials different from each other. The second optical portion is bonded to an optical functional face of the first optical portion. A concavoconvex face part is formed at the central part of the bond area between the first optical portion and the second optical portion.