Resin Layer Optical Element for Chromatic Aberration Correction
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Solution Overview
Problem
In optical systems for image pickup apparatuses, such as digital and video cameras, the reduction in total lens length leads to increased chromatic aberrations, which compromise optical performance, and the cementing of multiple optical members with resin layers poses challenges in precision and environmental resistance, particularly when forming optical elements with three or more members.
Innovation Solution
The optical element design includes a resin layer sandwiched between optical members, where the outer diameter of the resin layer is set larger than the effective region diameter of the cemented surface, ensuring minimal distortion and excellent environmental resistance, with specific refractive index and dispersion conditions to maintain optical performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If three or more optical members are cemented together to reduce chromatic aberration, then chromatic aberration correction is improved, but distortion and peeling occur due to bonding material
Solution Approach 1:
The patent extracts the harmful bonding material from the interface between optical members by introducing a resin layer that fills and covers the bonding material. This resin layer is formed on the outer surface of the first optical member and extends to cover the bonding material, effectively removing its harmful influence while maintaining the cemented structure.
Solution Approach 2:
The resin layer acts as an intermediary between the first optical member and the bonding material. It is formed on the outer surface of the first optical member and extends to cover the bonding material, serving as a protective mediator that prevents direct contact between the bonding material and the external environment, thereby reducing distortion and peeling.
2Reliability
If resin layer is formed on lens surface to provide aspherical shape, then optical performance is improved, but manufacturing precision decreases due to curing contraction
Solution Approach 1:
The patent changes the parameter of resin layer thickness to be very thin (0.1 to 5.0 mm) to minimize curing contraction. By controlling the thickness within this specific range, the resin layer provides the necessary aspherical shape while minimizing the absolute amount of curing contraction that would otherwise reduce surface precision.
3Reliability
If resin layer becomes thicker to improve environmental resistance, then environmental resistance is improved, but manufacturing precision and optical performance deteriorate
Solution Approach 1:
The patent optimizes the resin layer thickness parameter to a very thin range (0.1 to 5.0 mm) that provides sufficient environmental resistance while minimizing the impact on manufacturing precision. This thin thickness reduces the absolute amount of curing contraction and temperature-induced size changes that would otherwise degrade surface precision.
4Length of moving object
If total lens length is shortened for downsizing, then device size is reduced, but chromatic aberration increases
Solution Approach 1:
The patent uses a composite structure combining glass optical members and a resin layer with specific optical characteristics. The resin layer has refractive index and dispersion properties that differ from glass, allowing the combination to correct chromatic aberration while maintaining a compact total lens length.
Solution Approach 2:
The resin layer is applied locally on the outer surface of the first optical member, providing localized optical correction without requiring a complete redesign of the entire lens system. This local application allows chromatic aberration correction in a compact configuration.
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 reduces distortion and cement peeling, enhances environmental resistance, and achieves excellent chromatic aberration correction, resulting in improved optical performance and system compactness.
Implementation Method 1
a bonding material for bonding the second optical member to the resin layer
Data Source
AI summary
An optical element, which is composed of at least three optical members including a resin layer sandwiched between two optical members, has a high environmental resistance and optical performance, and has an excellent chromatic aberration correction effect. In the optical element, the resin layer is formed on one of light incident/exit surfaces of a first optical member, and a second optical member is cemented to the resin layer by a bonding material. A condition of φg<φr is satisfied, where φr indicates an outer diameter of the resin layer and φg indicates a diameter of cemented surface of the resin layer and the second optical member.