Objective Lens Aberration Control for Optical Pickup Devices
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional optical pickup devices face challenges in suppressing aberrations caused by tilts of optical components or light sources, which limits their performance in recording, reproduction, and erasing operations on tape-shaped recording media, particularly due to third-order coma aberrations.
Innovation Solution
The development of an objective lens that converges light with specific aberration conditions, such as |CML| + |CMF| ≈ 0.03λ and |CMD| < 0.02λ, to minimize aberrations when tilted, ensuring satisfactory performance even with tilts of the objective lens, light source, or recording medium.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional objective lenses are used, then the optical pickup device can perform basic recording and reproduction operations, but third-order coma aberrations increase when optical components or light sources are tilted, degrading performance
Solution Approach 1:
The patent applies parameter changes by precisely controlling the third-order coma aberration coefficients (CML and CMF) of the objective lens to satisfy specific mathematical relationships. By adjusting these optical parameters, the lens maintains stable performance under tilt conditions without requiring additional compensation mechanisms, thereby resolving the contradiction between reliability under tilt and manufacturing precision.
2Manufacturing precision
If additional compensation mechanisms are added to suppress aberrations, then aberration control improves, but device complexity and cost increase
Solution Approach 1:
The objective lens is designed to self-correct for tilt-induced aberrations through its inherent optical parameters. The lens structure itself provides the compensation function by satisfying specific coma aberration coefficient relationships, eliminating the need for external compensation mechanisms. This self-service approach resolves the contradiction between aberration control and device complexity.
3Measurement precision
If the objective lens is designed with strict aberration control, then recording accuracy improves, but manufacturing difficulty and cost increase
Solution Approach 1:
The patent defines specific parameter ranges for the third-order coma aberration coefficients (|CML| + |CMF| < 0.03λ and |CMD| < 0.02λ) that balance manufacturing feasibility with recording accuracy. These parameter specifications provide clear manufacturing targets while ensuring high spot formation accuracy, resolving the contradiction between measurement precision and ease of manufacture.
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 effectively reduces aberrations, allowing for high recording density and accurate spot formation on the recording medium without the need for additional compensation mechanisms, thereby enhancing the optical pickup device's performance and reducing costs and power consumption.
Implementation Method 1
an objective lens for performing at least one of recording, reproduction, and erasing of information on a tape-shaped recording medium by using light
Implementation Method 2
satisfies the following condition: |CML|+|CMF|<0.03λ where CML is an amount of a generated third-order coma aberration per 1 degree of tilt of the objective lens, and CMF is an amount of a generated third-order coma aberration per 1 degree of tilt of off-axis light
Data Source
AI summary
An objective lens capable of converging light of a used wavelength with a satisfactory aberration on a recording medium is provided. An objective lens for converging light of a predetermined wavelength λ on a recording medium satisfies the following condition: |CML|+|CMF|<0.03λ, where CML is an amount of a generated third-order coma aberration per 1 degree of tilt of the objective lens, and CMF is an amount of a generated third-order coma aberration per 1 degree of tilt of off-axis light.