Three-Lens Imaging System with Aperture Diaphragm for Telecentricity
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing imaging lenses face challenges in achieving telecentricity and minimizing manufacturing variations while being compact and high-performance, especially with increasing pixel density, as placing the aperture diaphragm closest to the object side can worsen telecentricity and increase sensitivity variations.
Innovation Solution
A three-lens configuration with a positive first lens, a meniscus second lens, and a third lens, optimized by specific conditional expressions to ensure telecentricity, reduce manufacturing sensitivity, and enhance optical performance, including aspherical lens surfaces to correct aberrations effectively.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the aperture diaphragm is placed at a position closest to the object side to ensure telecentricity, then telecentricity is improved, but variations in sensitivity due to manufacture increase and mass-production suitability worsens
Solution Approach 1:
The patent introduces a specific conditional expression (0.3 < f1/f2 < 1.0) as an intermediary constraint between the aperture diaphragm position and lens design parameters. This mathematical relationship acts as a mediator that allows the aperture to be positioned for telecentricity while compensating for manufacturing variations through controlled focal length ratios, thus resolving the contradiction between telecentricity improvement and manufacturing sensitivity reduction
2Volume of moving object
If a three-lens configuration is used to create a compact imaging lens, then device size is reduced, but optical performance (curvature of field and chromatic aberration correction) becomes more difficult to optimize
Solution Approach 1:
The patent applies parameter changes by establishing specific conditional expressions (0.3 < f1/f2 < 1.0 and 0.5 < f2/f3 < 2.0) that constrain the focal length ratios between lenses. These parameter constraints enable the compact three-lens configuration to achieve proper correction of curvature of field and chromatic aberration by optimizing the optical power distribution, thus resolving the contradiction between miniaturization and optical performance
3Volume of moving object
If the aperture diaphragm is placed between the first and second lenses in a middle aperture configuration to shorten lens length, then device size is reduced, but the angle of incidence of the principal ray to the imaging surface increases and telecentricity worsens
Solution Approach 1:
The patent uses parameter changes by defining the conditional expression (0.3 < f1/f2 < 1.0) that controls the optical power distribution. This parameter constraint allows the system to maintain telecentricity (small angle of incidence) even with the aperture positioned in the middle, by ensuring the first lens has sufficient positive power to counteract the aperture's effect on ray 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 solution achieves high optical performance, maintains telecentricity, and reduces manufacturing variations, enabling compact and high-resolution imaging lenses suitable for high-pixel density imaging elements.
Implementation Method 1
the first lens L1 is a positive lens having a convex surface on the object side
Implementation Method 2
the second lens L2 is a meniscus lens having a concave surface on the object side
Implementation Method 3
a third lens provided in order from the object side
Implementation Method 4
including aspherical lens surfaces to correct aberrations effectively
Data Source
AI summary
An imaging lens includes: in order from an object side, an aperture diaphragm; a first lens of a positive lens having a convex surface on the object side; a second lens of a meniscus lens having a concave surface on the object side; and a third lens. The imaging lens satisfies: f/f3<0.95 and BR2<0. BR2 satisfies BR2=A/D4, A represents a distance from a vertex position on a object-side surface of the second lens and on an optical axis to a position on a image-side surface of the second lens through which a light ray passes toward a corner of an image height, provided that a traveling direction of the light ray is taken as appositive direction, and D4 represents a center thickness of the second lens. f represents a focal length of the imaging lens. f3 represents a focal length of the third lens.