Zoom Lens System Using Plastic Aspheric Lenses
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional zoom lens systems with a four-times zoom ratio require a long overall length and increased cost due to the need for multiple spherical lenses for effective aberration correction, which complicates manufacturing and increases weight.
Innovation Solution
A four-group zoom lens system incorporating two plastic aspheric lenses and a resin hybrid lens, with specific refractive power conditions for each lens group, including a movable stop between the second and third lens groups, to reduce the number of constituent lenses and maintain a compact design while achieving a high zoom ratio.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If multiple spherical lenses are used for effective aberration correction, then image quality is improved, but the number of lenses and manufacturing cost increase
Solution Approach 1:
The patent employs aspheric surfaces on lenses instead of traditional spherical surfaces. The aspheric surfaces are defined by mathematical equations (e.g., x² + y² + z² = r² with additional aspheric terms) that allow precise control of light refraction, effectively correcting spherical aberration, coma, and other optical distortions that spherical lenses cannot correct, thereby reducing the number of lenses needed while maintaining high image quality
Solution Approach 2:
The patent uses plastic materials for lens fabrication instead of traditional glass. This allows for cost-effective injection molding of aspheric surfaces, combining the optical performance benefits of aspheric design with the manufacturing advantages of plastic materials, achieving both aberration correction and reduced production cost
2Adaptability or versatility
If three lens groups are adopted to provide four-times zoom ratio, then zoom capability is improved, but overall length of the lens system increases
Solution Approach 1:
The patent divides the zoom lens system into four distinct lens groups with specific refractive power configurations (positive, negative, positive, positive). This segmentation allows each group to perform specific optical functions, enabling compact arrangement that achieves four-times zoom ratio while controlling overall length, unlike conventional three-group designs that require longer configurations
Solution Approach 2:
The patent optimizes the refractive powers and focal lengths of individual lens groups within specific numerical ranges. By carefully selecting parameters such as the focal length of the second lens group (negative power) and the spacing between groups, the system achieves high zoom ratio in a compact form factor, balancing optical performance with physical dimensions
3Length of moving object
If four lens groups are adopted to reduce movement space, then compactness is improved, but the number of spherical lenses and manufacturing cost increase significantly
Solution Approach 1:
The patent strategically places aspheric surfaces on specific lenses within the four lens groups, particularly on the plastic lenses. These aspheric surfaces provide powerful aberration correction capabilities that allow the system to use fewer total lenses while maintaining compact dimensions, effectively replacing the need for multiple spherical correction lenses
Solution Approach 2:
The patent uses plastic material for lens fabrication instead of expensive glass, enabling cost-effective mass production through injection molding. This material substitution allows the four-group design to be economically viable despite the increased number of lens groups, as plastic lenses can be manufactured more cheaply and precisely with aspheric surfaces
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 system achieves a compact and cost-effective four-times zoom ratio with improved image resolution by reducing the number of lenses and using aspheric lenses made of plastic for efficient aberration correction, maintaining a balanced refractive power and minimizing astigmatism.
Implementation Method 1
an optical lens system is composed of a plurality of spherical lenses. However, spherical lenses cannot focus light from the center and periphery to the same point, which is called 'spherical aberration'
Implementation Method 2
The introduction of an aspheric surface effectively corrects aberration, and a corresponding aspheric lens functions equivalent to several spherical lenses
Data Source
AI summary
A zoom lens system includes, in order from an object side to an image side, a first positive lens group (G1), a second negative lens group (G2), a third positive lens group (G3), and a fourth positive lens group (G4). The second and third lens groups are movable for varying the focal length. The zoom lens system offers a four-times zoom ratio, and employs two plastic aspheric lenses (L3, L9) and a resin hybrid lens (L6). The first lens group consists of two lenses (L1, L2) arranged in an abutting relationship. The second and third lens groups each includes a pair of cemented lenses (L4, L5; L7, L8).