Zoom Lens Design for Wide-Angle High-Power Ratio
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Solution Overview
Problem
Existing compact zoom lenses for digital still cameras and video cameras face challenges in achieving a wide angle of view of 75° or more and a variable power ratio of about ×10 while maintaining a compact size, as they often require large lens diameters, long optical systems, or increased costs due to numerous lenses and movable parts.
Innovation Solution
A zoom lens design comprising a first lens group with positive refractive power, a second lens group with negative refractive power, a third lens group with positive refractive power, and a fourth lens group with positive refractive power, where the third lens group includes an aperture stop and cemented lenses to vary power by changing the interval between neighboring lens groups, ensuring telecentricity and controlling aberrations for downsizing and improved optical performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the third lens group is moved greatly to realize high variable power, then the variable power ratio is improved, but the whole optical system length increases and device size is enlarged
Solution Approach 1:
The lens system is divided into four distinct lens groups with specific refractive power assignments. The first lens group (positive) handles wide-angle coverage, the second lens group (negative) controls power variation, the third lens group (positive with aperture stop) manages telephoto coverage, and the fourth lens group (positive) optimizes image quality. This segmentation allows each group to perform its function efficiently without requiring excessive movement of any single group.
Solution Approach 2:
The patent employs dynamic adjustment of intervals between neighboring lens groups to vary the power of the zoom lens. By changing the spacing between lens groups rather than moving individual groups excessively, the system achieves high variable power ratio (×10 or more) while maintaining compact optical system length. The aperture stop in the third lens group is also dynamically positioned to control light paths at different zoom positions.
2Reliability
If a large number of lenses are used to obtain high variable power ratio and excellent optical performance, then the optical performance is improved, but the manufacturing cost increases
Solution Approach 1:
The patent combines multiple lens elements into four integrated lens groups, each performing specific functions. The third lens group combines the aperture stop with cemented lenses (positive and negative) to achieve both light control and power variation in a single assembly. This merging reduces the total number of separate lens components while maintaining excellent optical performance across the ×10 variable power ratio range.
Solution Approach 2:
The patent utilizes cemented lenses combining different glass materials with complementary refractive indices and aberration characteristics. The third lens group employs cemented lenses formed by a positive lens and a negative lens to correct chromatic aberrations and control power distribution. This composite approach achieves superior optical performance with fewer discrete lens elements, reducing manufacturing complexity and cost.
3Adaptability or versatility
If the first lens group is moved greatly for varying power, then the variable power ratio is improved, but the length of the whole lens system becomes long and device size is enlarged
Solution Approach 1:
Instead of moving the first lens group greatly, the patent dynamically adjusts the intervals between all neighboring lens groups. The first lens group remains relatively stationary while the spacing between groups changes to achieve power variation. This dynamic interval adjustment achieves high variable power ratio without requiring large movements of any single group, thereby maintaining compact device size.
4Adaptability or versatility
If a stop is moved in the optical system to achieve high variable power ratio, then the variable power ratio is improved, but the number of movable parts increases and device size is enlarged
Solution Approach 1:
The aperture stop is merged with the third lens group, which itself contains cemented lenses (positive and negative). This combination allows the third lens group to simultaneously function as both an aperture control element and a power variation element. By integrating the stop function into an existing lens group rather than adding a separate movable stop mechanism, the system achieves high variable power ratio without increasing the number of movable parts.
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 high variable power of ×10 or more with excellent optical performance, reduces the size and weight of the lens system, and enhances mass productivity by minimizing the number of lenses and movable parts, while maintaining a wide angle of view and telecentricity required for CCD or CMOS image pickup elements.
Implementation Method 1
a first lens group with positive refractive power, a second lens group with negative refractive power, a third lens group with positive refractive power, and a fourth lens group with positive refractive power
Implementation Method 2
a cemented lens formed by a positive lens in a biconvex shape and a negative lens
Data Source
AI summary
There is provided a zoom lens which is suitable for a digital still camera and a video camera and includes a small number of lenses, especially a zoom lens which has an angle of view of 75° or more at the wide-angle end and a variable power ratio of about ×10. The zoom lens includes a first lens group with positive refractive power, a second lens group with negative refractive power, a third lens group with positive refractive power, and, a fourth lens group with positive refractive power. The zoom lens varies power by changing an interval of each neighboring lens groups. The first lens group is composed of a negative lens and a positive lens. The third lens group is composed of an aperture stop, a cemented lens formed by a positive lens in a biconvex shape and a negative lens, and a positive lens.