Compact Optical System Aberration Control via Negative Lens Parameter Optimization
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Solution Overview
Problem
High-performance, compact optical systems with small F-number (bright) lenses face challenges in reducing weight while achieving aberration correction and miniaturization, particularly as the F-number decreases, due to unsuitable refractive power and shape of negative lenses closest to the image side.
Innovation Solution
The optical system consists of a front lens unit and a negative lens on the image side, with specific inequalities governing the focal lengths, aperture stop diameters, and lens surface distances to correct aberrations and reduce size, including aspherical surfaces and a configuration of negative, positive lenses to achieve a wide-angle, high-aperture ratio.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If the F-number is decreased to create a bright optical system, then light gathering capability is improved, but weight increases and aberration correction becomes difficult
Solution Approach 1:
The patent applies parameter changes by optimizing the refractive power and shape parameters of the negative lens Gn closest to the image side. Specifically, it sets the focal length ratio fn/f within -10.0 to -1.0 and the sagitta ratio SAG1/f within 0.16 to 0.50, which enables achieving F-number 2.0 or smaller while controlling weight and aberrations through precise parameter optimization rather than simply increasing aperture size.
Solution Approach 2:
The patent employs composite materials by combining resin lenses with glass lenses in the optical system. The negative lens Gn and other elements use different materials (resin or glass) selected for their specific refractive indices and Abbe numbers, creating a composite optical system that achieves bright performance with controlled weight and aberration correction.
2Illumination intensity
If the F-number is decreased to create a bright optical system, then light gathering capability is improved, but aberration correction becomes difficult
Solution Approach 1:
The patent addresses aberration correction by precisely controlling the shape parameters of the negative lens Gn, specifically setting the on-axis distance ratio SAG1/f between 0.16 and 0.50. This parameter optimization ensures that the lens curvature and thickness are suited for correcting spherical aberration and other distortions while maintaining the bright F-number 2.0 or smaller performance.
Solution Approach 2:
The patent uses composite materials with different optical properties (resin and glass lenses with varying refractive indices and Abbe numbers) to correct aberrations. By combining materials with complementary characteristics, the system achieves superior aberration correction compared to single-material systems, enabling high-performance imaging at small F-numbers.
3Illumination intensity
If the aperture is increased to create a bright optical system, then light gathering capability is improved, but system size increases
Solution Approach 1:
The patent reduces system size by optimizing the focal length ratio fn/f of the negative lens Gn to be between -10.0 and -1.0. This parameter control allows the optical system to achieve F-number 2.0 or smaller without proportionally increasing the overall lens diameter and system volume, thereby maintaining compactness while improving light gathering capability.
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 creation of a compact, lightweight optical system with reduced ghosting and improved light intensity, capable of providing high-resolution images across a wide angle of view while maintaining a sufficient light amount ratio.
Implementation Method 1
the refractive power and the shape of a negative lens closest to the image side are not suited
Data Source
AI summary
A system consists of a front lens unit and a negative lens on an image side of the front lens unit. A focal length of the system, a focal length of the negative lens, an effective diameter of a lens surface on an object side of the negative lens, a diameter of an aperture stop that determines an on-axis ray, and an on-axis distance from an endmost point in a light effective area of the lens surface on the object side of the negative lens to an on-axis point of the negative lens satisfy predetermined inequalities.