Fixed-Focus Imaging Lens with Aspheric Groups for Large Sensors
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Solution Overview
Problem
Conventional wide-angle lenses face challenges in providing good imaging quality on sensors with large target areas while meeting demands for both wide fields of view and large apertures, due to limitations in lens shape and material.
Innovation Solution
A fixed-focus imaging lens design comprising a first lens group with two plastic aspheric lenses and a second lens group with three plastic aspheric lenses, including a glass lens closest to the object side, along with an aperture stop, which achieves a diagonal field of view of 140 to 165 degrees and maintains high imaging quality for both visible and infrared light, even on large sensors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of moving object
If conventional wide-angle lens design is used, then wide field of view is achieved, but imaging quality on large sensor target areas deteriorates
Solution Approach 1:
The lens system is divided into multiple lens groups (first lens group with two plastic aspheric lenses, second lens group with three plastic aspheric lenses) separated by an aperture stop. This segmentation allows each group to be optimized for specific optical functions, enabling wide field of view while maintaining imaging quality on large sensor areas.
Solution Approach 2:
The lens system combines plastic aspheric lenses with glass lenses (the first lens and fourth lens are glass lenses). This composite material approach leverages the advantages of both materials to achieve both wide field of view and high imaging quality, while the specific material selection helps with temperature resistance.
2Ease of manufacture
If lens shape and material are limited, then manufacturing is simplified, but imaging quality on large sensors deteriorates
Solution Approach 1:
The patent employs aspheric lenses with specific curvature parameters (K values ranging from -3.97 to 7.84) to correct optical aberrations. The aspheric surfaces provide superior optical performance on large sensor areas while remaining manufacturable through standard molding processes for plastic lenses.
3Temperature
If glass lens is used for object-side lens, then temperature resistance is improved, but manufacturing complexity increases
Solution Approach 1:
Glass lenses are strategically positioned at specific locations (first lens and fourth lens) where temperature resistance is most critical, while other lenses use plastic aspheric materials. This localized application of different materials optimizes temperature resistance without unnecessarily complicating the entire lens structure.
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 good imaging quality with wide fields of view and large apertures, maintains quality on sensors with large target areas, withstands higher temperatures, reduces manufacturing costs, and ensures high imaging performance across a broad temperature range.
Implementation Method 1
a first lens group, an aperture stop and a second lens group arranged in order from an object side to an image side of the fixed-focus imaging lens
Implementation Method 2
the first lens group comprises two plastic aspheric lenses, the second lens group comprises three plastic aspheric lenses
Implementation Method 3
a lens in the first lens group closest to the object side is a glass lens... the fixed-focus imaging lens is allowed to withstand higher temperatures
Data Source
AI summary
A fixed-focus imaging lens includes a first lens group, an aperture stop and a second lens group arranged in order from an object side to an image side of the fixed-focus imaging lens. A focal plane for visible light with a wavelength of 550 nm along an optical axis of the imaging lens is less than 0.01 mm. The fixed-focus imaging lens satisfies a condition of 45<LT/GD, where LT is a distance measured along the optical axis between two outermost lens surfaces with refractive powers at opposite ends of the imaging lens, and GD is a distance measured along the optical axis between the first lens group and the second lens group.