Radial-Zone Phased Metalens for Fixed-Focus Camera MTF
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Fixed-focus cameras often fail to achieve sufficient focus ability across an entire field of view due to variations in back focal length and depth of focus, leading to discarded lenses and increased production costs, especially in automotive applications.
Innovation Solution
Implementing a phased metalens between the objective lens and camera imager to compensate for variations in back focal length, increasing the depth of focus and improving modular transfer function performance across radial zones.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a fixed-focus lens is used to simplify the camera system, then device complexity is reduced, but manufacturing precision becomes critical because even minor deficiencies in MTF at a few field positions prevent lenses from being focused over a desired field
Solution Approach 1:
The patent applies parameter changes by modifying the back focal length (BFL) across different radial zones of the lens. Instead of maintaining a uniform BFL, the patent creates zone-specific BFL variations that compensate for field curvature and optimize MTF across the entire field of view. This allows a single fixed-focus lens to achieve acceptable focus performance across multiple zones without requiring complex active focusing mechanisms.
Solution Approach 2:
The patent implements local quality by assigning different back focal lengths to different radial zones within the lens field. Each zone is optimized independently with its own BFL value, allowing the lens to achieve optimal MTF performance locally in each zone while maintaining a simple fixed-focus overall structure. This zone-based approach resolves the contradiction by making the lens performance locally optimized rather than uniformly constrained.
2Manufacturing precision
If lenses are discarded due to insufficient MTF upon integration, then manufacturing precision requirements are maintained, but productivity decreases and costs increase due to lens replacement needs
Solution Approach 1:
The patent changes the BFL parameter across radial zones to expand the acceptable range of lens performance. By creating zone-specific focus optimization, the patent allows lenses with varying manufacturing tolerances to be utilized effectively. This parameter variation approach converts previously discarded lenses into usable components, maintaining MTF standards while improving productivity.
Solution Approach 2:
The patent recovers lenses that would otherwise be discarded due to insufficient MTF performance at certain field positions. By applying zone-based BFL optimization, the patent enables these previously rejected lenses to achieve acceptable focus performance across the desired field, thereby reducing waste and improving production throughput without compromising quality standards.
3Manufacturing precision
If replacement lenses are used to achieve sufficient MTF, then manufacturing precision is maintained, but device complexity and cost increase
Solution Approach 1:
The patent changes the back focal length parameter across different radial zones to achieve sufficient MTF performance with a single lens design. This parameter modification eliminates the need for lens replacement or complex multi-lens assemblies, maintaining focus ability while reducing device complexity and cost.
4Manufacturing precision
If the back focal length is adjusted to set the lens at a precise fixed position, then manufacturing precision is improved, but adaptability decreases because lenses cannot be focused over a desired field
Solution Approach 1:
The patent applies local quality by implementing different back focal lengths for different radial zones within the lens. This allows the lens to be precisely optimized for each zone's specific requirements, achieving both precise positioning (manufacturing precision) and broad field coverage (adaptability). Each zone adapts to its local optical requirements while maintaining overall system coherence.
Solution Approach 2:
The patent utilizes parameter changes by varying the back focal length across radial zones rather than maintaining a single fixed BFL. This parameter variation enables the lens to adapt to different field positions, expanding field coverage capability while maintaining precise focus control in each zone, thereby resolving the contradiction between precision and adaptability.
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
Enhances image quality and focus margin across the entire field of view, allowing the use of less expensive lenses and reducing production delays and costs while maintaining high performance for automotive applications.
Implementation Method 1
a phased metalens configured to compensate for defocus caused by the different back focal lengths by increasing, across the radial zones within the field of view, a depth of the focus window
Data Source
AI summary
Described is phased metalens depth of focus increase for camera focusing. An objective camera lens is configured to provide a focus window across multiple radial zones within a field of view. A camera imager is configured to capture an image of the field of view. When at least two of the radial zones have different back focal lengths relative the imager and the objective lens, a phased metalens is positioned between the objective lens and the camera imager. The metalens is configured to compensate for defocus caused by the different back focal lengths by increasing, across the radial zones within the field of view, a depth of the focus window. The metalens improves focus across the field of view, which prevents variations in objective lens characteristics from reducing image quality.