Wide-Angle Lens Design for Aberration Correction
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Solution Overview
Problem
Wide-angle lenses face challenges in miniaturization and light amount loss due to increased number of lens elements, leading to higher costs and weight, while lenses with fewer elements suffer from reduced light incidence at high image heights and increased chromatic aberrations.
Innovation Solution
A wide-angle lens design with a total of five lens elements, including two negative and three positive power elements, where the rear lens group corrects aberrations and reduces the incident angle of chief rays, using aspheric surfaces and specific Abbe's numbers to minimize light loss and chromatic aberrations, and employing glass and plastic materials for cost-effectiveness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If many lens elements are used to correct aberrations, then the degree of freedom in designing increases and various aberrations are corrected, but the overall length of the imaging lens system becomes long and miniaturization becomes difficult
Solution Approach 1:
The patent applies parameter changes by carefully selecting specific focal lengths, Abbe's numbers, and curvature radii for each lens element. The front lens group uses negative power elements with specific Abbe's numbers (ν1 > 20, ν2 > 20) while the rear lens group uses positive power elements (ν3 < 50, ν4 < 50). These parameter optimizations allow effective aberration correction with only five lens elements, avoiding the need for longer optical paths required by conventional designs with more elements.
Solution Approach 2:
The imaging lens system is segmented into two functional groups: a front lens group (first, second, and third lens elements) responsible for light gathering and initial aberration correction, and a rear lens group (fourth and fifth lens elements) responsible for final focus and aberration refinement. This segmentation allows each group to be optimized for its specific function, achieving comprehensive aberration correction with fewer total elements.
2Device complexity
If a single positive power lens element is used behind the aperture, then the number of lens elements is reduced, but the incident angle of chief ray at high image height becomes large causing light amount loss
Solution Approach 1:
Instead of using a single positive power lens element behind the aperture as in conventional designs, this patent inverts the approach by placing negative power lens elements (first and second lens elements) at the front of the optical system. This inversion allows better control of chief ray angles throughout the optical path, ensuring that even at high image heights, the incident angles remain within acceptable ranges to prevent light amount loss while maintaining a compact five-element structure.
Solution Approach 2:
Different regions of the optical system are assigned different lens element characteristics tailored to local requirements. The front lens group uses negative power elements with high Abbe's numbers to control off-axis rays and chief ray angles. The rear lens group uses positive power elements with lower Abbe's numbers for final focus. This local optimization ensures that each part of the system contributes maximally to controlling light paths, maintaining adequate light incidence angles across the entire image sensor surface.
3Adaptability or versatility
If the incident angle of chief ray becomes large, then the angle of view can be wide, but the luminous flux that can be led to pixel decreases causing light amount loss
Solution Approach 1:
The patent employs dynamic optical design where the five lens elements work cooperatively to dynamically adjust light paths across different field angles. The negative power front elements and positive power rear elements create a balanced optical system that can handle wide angle of view requirements while dynamically controlling chief ray angles to prevent excessive incidence angles at the image sensor, thereby minimizing luminous flux loss across the entire angular range.
Solution Approach 2:
The patent uses composite material properties by selecting lens elements with different Abbe's numbers (ν1 > 20, ν2 > 20 for front group; ν3 < 50, ν4 < 50 for rear group). This composite approach allows the system to simultaneously achieve wide angle of view and control chromatic aberrations while maintaining appropriate chief ray angles. The variation in dispersion properties across the five elements enables sophisticated control of light paths, ensuring adequate light transmission even at wide angles.
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 design achieves a wide-angle view exceeding 180 degrees with reduced light loss and chromatic aberrations, maintaining image resolution and miniaturizing the lens system while keeping costs low.
Implementation Method 1
an imaging lens system, including: a front lens group arranged on an object side, a rear lens group arranged on an image side
Implementation Method 2
the fifth lens element is constructed of an aspheric lens such that an angle between a chief ray radiated from the fifth lens element and the optical axis becomes smaller
Data Source
AI summary
A wide-angle lens comprising: an imaging lens system, including: a front lens group, an aperture, and a rear lens group, arranged in that order from an object side to an image side; wherein said front lens group comprises first and second lens elements, having negative power respectively, and a third lens that is a positive lens, arranged in that order from the object side to an aperture side; wherein said rear lens group comprises fourth and fifth lens elements, having positive power respectively, arranged in order from the aperture side to the image side; where an incident angle to an optical axis of the imaging lens system of a chief ray of a maximum angle of view passing through the aperture is θI, the following Expression 1 is satisfied.40° (degrees)<θI<60° (degrees) Expression 1.