Three-Aspheric Attachment Lens for Chromatic Aberration Suppression

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Solution Overview

Problem

Existing attachment lenses disrupt the aberration balance and deteriorate the optical performance of imaging lenses when mounted, limiting their ability to achieve high resolution and wide field of view.

Innovation Solution

An attachment lens comprising three aspheric lenses with specific optical power and refractive index ratios, satisfying expressions (1) to (11), which suppresses chromatic aberration and maintains image flatness when integrated with an imaging lens.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If an attachment lens is mounted on an imaging lens to widen the angle of view and increase magnification, then the field of view and magnification are improved, but the aberration balance is disrupted and optical performance deteriorates

Engineering Contradiction:
Improvefield of view and magnificationVSAvoidoptical performance
Core Design Contradiction:
Adaptability or versatilityVSReliability

Solution Approach 1:

The attachment lens is divided into three separate lens elements (first lens with positive/negative power, second lens with positive power, third lens with positive/negative power) arranged in sequence. This segmentation allows each lens to be optimized for specific functions: the first lens for angle of view control, the second lens for magnification and chromatic aberration correction, and the third lens for image plane flatness maintenance, thereby achieving wide field of view and high magnification without compromising overall optical performance

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

Each lens element is designed with aspheric surfaces having specific local optical properties. The first lens has aspheric surfaces optimized for wide-angle light control, the second lens has aspheric surfaces tailored for chromatic aberration correction with specific refractive index requirements (n2 between 1.40-1.80), and the third lens has aspheric surfaces designed for maintaining image plane flatness. This local optimization of each lens element's quality enables the attachment lens to achieve multiple functions simultaneously without disrupting the imaging lens's aberration balance

Inventive Principle:
Principle #3Local quality

2Measurement precision

If an attachment lens is designed to observe fine target objects with high resolution, then measurement precision is improved, but device complexity increases due to multiple lens elements and aspheric surfaces

Engineering Contradiction:
ImproveresolutionVSAvoidlens structure
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

Both surfaces of each of the three lens elements are designed as aspheric surfaces rather than simple spherical surfaces. This allows for precise control of light rays across the entire field of view, enabling high-resolution imaging of fine target objects. The aspheric surfaces correct for spherical aberration and other monochromatic aberrations that would otherwise limit resolution, achieving measurement precision comparable to complex multi-element imaging lenses while maintaining a relatively compact attachment lens structure

Inventive Principle:
Principle #14Spheroidality (Curvature)

Solution Approach 2:

The invention specifies precise parameter ranges for each lens element to optimize resolution while controlling complexity: the focal length ratios (f1/f between -0.1 and -5.0, f2/f between 0.5 and 3.0, f3/f between 0.1 and 5.0), refractive indices (n2 between 1.40-1.80, n3 between 1.40-1.80), and Abbe numbers (v2 between 20-60, v3 between 20-60). These parameter constraints guide the design process to achieve high resolution with a manageable three-element structure rather than requiring numerous lens elements

Inventive Principle:
Principle #35Parameter changes

3Reliability

If an attachment lens uses multiple lens elements with different refractive indices to suppress chromatic aberration, then optical performance is improved, but manufacturing precision requirements increase

Engineering Contradiction:
Improvechromatic aberration suppressionVSAvoidlens fabrication
Core Design Contradiction:
ReliabilityVSManufacturing precision

Solution Approach 1:

The attachment lens employs three different lens materials with specifically selected refractive indices and Abbe numbers. The second lens uses material with n2 between 1.40-1.80 and v2 between 20-60, while the third lens uses material with n3 between 1.40-1.80 and v3 between 20-60. This composite material approach enables effective chromatic aberration suppression across the visible spectrum. The aspheric surfaces of each element are designed to work synergistically with these material properties, achieving high optical performance with manageable manufacturing precision requirements through coordinated design of geometry and material properties

Inventive Principle:
Principle #40Composite materials

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 attachment lens maintains optical performance, enabling high-resolution and wide-field observation without deteriorating the imaging lens's performance, even when used in ultraviolet light analysis.

Implementation Method 1

each of both surfaces of the first lens (101), the second lens (102), and the third lens (103) is an aspheric surface

Methodology Applied
Scientific EffectRefraction: Refraction

Data Source

PatentEP4692887A1Attachment lens
Publication Date: 2026.02.11 MITSUBISHI GAS CHEM CO INC
  • EP4692887A1 patent drawingFigure 1~2
  • EP4692887A1 patent drawingFigure 3~4
  • EP4692887A1 patent drawingFigure 5

AI summary

The present disclosure relates to an attachment lens including a first lens having positive or negative optical power, a second lens having positive optical power, and a third lens having positive or negative optical power in order from an object side, wherein each of both surfaces of the first lens, the second lens, and the third lens is an aspheric surface, and the attachment lens satisfies the following expressions (1), (2), (3), (4), (5), and (6): −10.0≤f1/f≤8.00 −0.1500≤φ1/ν1≤0.0500 0.100≤φ2/n2≤2.000 −80.0≤f3/f≤30.0 −0.300≤φ3/n3≤0.900 −0.0200≤φ3/ν3≤0.0500