Galileo Imaging Lens Inversion for Miniaturized CMOS Resolution
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Solution Overview
Problem
Existing imaging lenses for miniaturized CMOS image sensors face challenges in achieving high resolution and contrast due to complex structures and the inability to maintain a contrast of Modulation Transfer Function (MTF) value over 20% for 1.4 μm×1.4 μm pixel elements.
Innovation Solution
The proposed imaging lens features a front group of lenses with a diaphragm and a convex-concave Galileo system, where the Galileo system is fixed near the imaging plane, allowing for simple focusing by advancing the front group of lenses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a floating mechanism is used where the lens group at the imaging side moves for focusing, then focusing is achieved, but the structure becomes complicated and hard to handle
Solution Approach 1:
Instead of moving the imaging-side lens group for focusing (conventional approach), the patent inverts the approach by moving the object-side lens group. This reversal simplifies the focusing mechanism while maintaining optical performance, directly resolving the contradiction between operational simplicity and structural complexity
Solution Approach 2:
The lens is divided into distinct functional groups: an object-side lens group that moves for focusing, a fixed intermediate group, and an imaging-side group. This segmentation allows independent optimization of each group's function, simplifying the overall focusing mechanism while maintaining high resolution
2Measurement precision
If the pixel size is miniaturized to enhance image resolution, then higher resolution is achieved, but maintaining MTF contrast over 20% becomes difficult
Solution Approach 1:
The patent applies different optical characteristics to different lens groups: the object-side group has specific curvature and refractive properties optimized for miniaturized pixels, while the intermediate and imaging groups have tailored properties to maintain contrast. This local optimization ensures MTF contrast over 20% is maintained across the entire imaging plane
Solution Approach 2:
The patent optimizes specific optical parameters including curvature radii, refractive indices, and group spacing to achieve the desired balance between resolution and contrast. By carefully adjusting these parameters, the system maintains MTF contrast over 20% while supporting miniaturized pixel sizes
3Ease of operation
If the lens group at the imaging side moves for focusing, then focusing is enabled, but the lens group cannot always be placed near the imaging plane
Solution Approach 1:
The patent inverts the conventional focusing approach by moving the object-side lens group instead of the imaging-side group. This allows the imaging-side lens group to remain fixed near the imaging plane, eliminating positioning precision requirements while maintaining focusing capability through the inverted mechanism
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
This configuration enables the imaging lens to achieve a resolution corresponding to miniaturized image sensor elements while maintaining MTF over 20% at 1.4 μmL&S across the entire imaging plane, from infinity to close-up distances.
Implementation Method 1
a convex-concave Galileo system formed with a convex lens at a front group side and a concave lens at an imaging plane side
Implementation Method 2
a front group of imaging lens, which include a plurality of lenses anteroposteriorly arranged with an diaphragm interposed therein
Data Source
AI summary
Provided is an imaging lens consisting of a front-group imaging lens having a plurality of lenses in front and behind a diaphragm, and a convex-concave Galilean system composed of a convex lens on the front group side and a concave lens on the imaging plane side, the imaging lens performing focusing by fixing the convex-concave Galileo system near the imaging plane and extending the front-group imaging lens, wherein the surface on the imaging plane side of the lens at the end of the Galileo system on the imaging plane side is a flat surface, and the flat surface is in contact with the end of an image sensor on the imaging lens side, or the front-group imaging lens is a four-group, six-element Gauss lens, a four-group, seven-element Summitar lens, or a five-group, seven-element modified Summitar lens obtained by separating a Summitar front-lens-element doublet lens.