Single Objective Lens with Diffraction Unit for Multi-Wavelength Optical Pickup
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Solution Overview
Problem
Existing optical pickups require multiple objective lenses and complex configurations to achieve compatibility with different optical disc formats, leading to increased size, weight, and cost, as well as degraded signal quality due to unsuitable lens inclination and increased parts, making them inefficient for recording and playback across various disc types.
Innovation Solution
A condensing optical device using a single objective lens with a diffraction unit that includes multiple diffraction regions, each configured to handle specific wavelengths, allowing for the efficient condensation of optical beams onto signal recording surfaces of different optical discs, thereby simplifying the optical pickup design and improving compatibility.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If multiple objective lenses are provided for different optical disc formats, then compatibility with various disc types is achieved, but device complexity and size increase
Solution Approach 1:
The patent applies universality by designing a single objective lens that can focus optical beams of three different wavelengths (780nm for CD, 650nm for DVD, 405nm for BD) onto the signal recording surfaces of respective optical discs. This eliminates the need for multiple dedicated objective lenses, reducing device complexity while maintaining compatibility across all disc formats
Solution Approach 2:
The patent merges the functions of multiple objective lenses into a single lens by integrating a diffraction unit with the objective lens. The diffraction unit contains multiple diffraction regions with different structures that work together to handle different wavelengths, combining what would have been separate optical systems into one unified component
2Adaptability or versatility
If multiple objective lenses are provided for different optical disc formats, then compatibility with various disc types is achieved, but weight increases
Solution Approach 1:
The single objective lens serves multiple functions by focusing three different wavelengths onto respective disc types, eliminating the need for multiple heavy lens assemblies. The diffraction unit integrated with the lens enables this multi-functional capability without significantly increasing weight
3Adaptability or versatility
If multiple objective lenses are provided for different optical disc formats, then compatibility with various disc types is achieved, but manufacturing cost increases
Solution Approach 1:
The single objective lens design reduces the number of components that need to be manufactured, assembled, and quality-tested. By making one lens serve multiple wavelength functions through the integrated diffraction unit, manufacturing processes are simplified and costs are reduced compared to producing and assembling multiple separate lens systems
4Adaptability or versatility
If multiple objective lenses are provided for different optical disc formats, then compatibility with various disc types is achieved, but the attachment angle becomes unsuitable leading to degraded signal quality
Solution Approach 1:
The single objective lens is designed with a unified attachment angle that is optimized for all three wavelengths simultaneously. The diffraction unit compensates for wavelength-specific requirements, allowing the lens to maintain suitable signal quality across CD, DVD, and BD formats without the attachment angle problems that arise when using multiple lenses with different mounting configurations
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 enables good recording and playback compatibility across three types of optical discs with different wavelengths using a single objective lens, reducing unwanted light incidence and increasing light use efficiency, thus addressing the inefficiencies of previous multi-lens systems.
Implementation Method 1
a diffraction unit having a substantially circular first diffraction region provided on an innermost portion, a ring zone-shaped second diffraction region provided outside the first diffraction region, and a ring zone-shaped third diffraction region provided outside the second diffraction region
Data Source
AI summary
An optical pickup includes: a first emission unit emitting an optical beam with a first wavelength corresponding to a first optical disc; a second emission unit emitting an optical beam with a second wavelength, which is longer than the first wavelength, corresponding to a second optical disc different from the first optical disc; a third emission unit emitting an optical beam with a third wavelength, which is longer than the second wavelength, corresponding to a third optical disc different from the first and second optical discs; a condensing optical device condensing, on a signal recording surface of a corresponding optical disc, the optical beams emitted from the first to third emission units; and a diffraction unit provided in the condensing optical device, which is disposed on the optical path of the optical beams with the first to third wavelengths.