Camera Optical Lens Free-Form Surface Distortion Correction
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Solution Overview
Problem
Existing camera optical lenses with wide angles and high pixel imaging elements face challenges in achieving low TV distortion (<1.0%) and excellent optical performance, particularly due to insufficient correction of distortion ratios and focal length relationships among lens elements.
Innovation Solution
A camera optical lens design with seven lenses, where specific ratios of focal lengths and on-axis distances are optimized, and the image-side surface of the seventh lens is set as a free-form surface, satisfying conditions such as |f2/f3|≤0.07 and 0.35≤D23/f≤0.45, to improve distortion correction and achieve a full viewing angle of more than 110 degrees.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the focal length ratios and on-axis distances are not optimized, then the lens structure is simpler, but the TV distortion correction is insufficient (|TV_D|>1.0%)
Solution Approach 1:
The patent applies parameter changes by precisely controlling the focal length ratios (f2/f3, f2/f4) and on-axis distances (D12, D23) of lens elements. By optimizing these parameters within specific ranges, the design achieves |TV_D|≤1.0% distortion correction while maintaining a manageable seven-lens structure, resolving the contradiction between distortion correction precision and structural complexity.
Solution Approach 2:
The patent employs free-form surfaces on specific lens elements (particularly the seventh lens) to correct distortion. The free-form surface geometry allows for precise control of light ray paths across the field of view, enabling superior distortion correction without requiring an excessive number of lens elements.
2Manufacturing precision
If more lens elements are added to improve optical performance, then the distortion correction improves, but the device complexity increases
Solution Approach 1:
Instead of simply adding more lens elements, the patent optimizes the parameters of existing seven lenses, including focal lengths, on-axis distances, and refractive indices. This parameter optimization achieves excellent optical performance (|TV_D|≤1.0%, 2ω>110°) without increasing the number of lens elements beyond seven.
Solution Approach 2:
The introduction of free-form surfaces on specific lens elements provides additional degrees of freedom for correcting optical aberrations. This allows the seven-lens system to achieve performance that would typically require more conventional spherical lens elements.
3Area of stationary object
If the focal length ratios are increased to improve wide-angle performance, then the full viewing angle increases, but the distortion correction becomes insufficient
Solution Approach 1:
The patent achieves the dual goal of wide-angle performance (2ω>110°) and distortion correction (|TV_D|≤1.0%) by carefully controlling the focal length ratios (|f2/f3|≤0.07, −0.50≤f2/f4≤−0.30) and on-axis distances (0.58≤D12/f≤0.64, 0.35≤D23/f≤0.45). These parameter constraints ensure that the wide-angle capability does not compromise distortion correction.
Solution Approach 2:
The free-form surface on the seventh lens element provides the necessary correction for distortion that arises from wide-angle geometry. The non-spherical surface profile compensates for the barrel distortion inherent in wide-angle designs, enabling both large field of view and accurate image geometry.
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 lens design effectively reduces TV distortion to less than 1.0%, enhancing optical performance and achieving a wide angle view, suitable for smartphone and webcam applications with high-pixel imaging elements.
Implementation Method 1
a seventh lens having a negative refractive power and provided with an image-side surface as a free-form surface
Data Source
AI summary
The present invention relates to a field of optical lens, and provides a camera optical lens including, from an object side to an image side in sequence: a first lens having a negative refractive power, a second lens having a positive refractive power, a third lens, a fourth lens having a negative refractive power, a fifth lens having a positive refractive power, a sixth lens, a seventh lens having a negative refractive power and provided with an image-side surface as a free-form surface; and the camera optical lens satisfies conditions of: |f2/f3|≤0.07; −0.50≤f2/f4≤−0.30; 0.58≤D12/f≤0.64; and 0.35≤D23/f≤0.45. The camera optical lens provided by the present disclosure has |TV_D|<1.0%, has excellent optical performance, is of wide angle with 2ω>110°, and includes seven lenses.