Plastic Imaging Lens Diffractive Surface Chromatic Aberration

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Solution Overview

Problem

Conventional imaging lenses for mobile devices face challenges in achieving high-performance chromatic aberration correction and compactness due to limitations in aberration correction methods, particularly with high-resolution image pickup devices and temperature-dependent plastic lens refractive indices.

Innovation Solution

A compact imaging lens design utilizing two diffractive optical surfaces on aspheric lenses made of plastic material, strategically placed to correct chromatic aberration and other aberrations, with specific conditional expressions for lens focal lengths and refractive powers to optimize performance.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If conventional lens array combination is used for chromatic aberration correction, then chromatic aberration can be corrected, but the number of lenses increases and the total optical length increases

Engineering Contradiction:

Improvechromatic aberration correctionVSAvoidnumber of lenses

Core Design Contradiction:

Manufacturing precisionVSDevice complexity

Solution Approach 1:

The patent replaces the conventional mechanical lens array combination with a diffractive optical surface that uses diffraction physics to correct chromatic aberration. The diffractive surface with negative Abbe number characteristics enables chromatic aberration correction through optical diffraction rather than mechanical lens stacking, thereby reducing the number of lenses while maintaining correction effectiveness

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent changes the fundamental parameter of chromatic aberration correction from positive Abbe number glass materials to negative Abbe number diffractive surface. This parameter change allows a single lens with diffractive surface to achieve what previously required multiple lenses, shortening the total optical length while maintaining correction capability

Inventive Principle:

Principle #35Parameter changes

2Manufacturing precision

If glass material is used for lenses, then chromatic aberration correction is achieved, but manufacturing cost increases

Engineering Contradiction:

Improvechromatic aberration correctionVSAvoidmanufacturing cost

Core Design Contradiction:

Manufacturing precisionVSEase of manufacture

Solution Approach 1:

The patent replaces expensive glass lens materials with plastic lens materials that have diffractive surfaces formed thereon. Plastic materials are significantly cheaper and easier to manufacture than glass, while the diffractive surface technology enables the plastic lenses to achieve chromatic aberration correction comparable to or better than conventional glass lens combinations

Inventive Principle:

Principle #27Cheap short-living objects (Disposable)

Solution Approach 2:

The patent creates a composite structure by combining plastic lens material with a diffractive optical surface. This composite approach leverages the manufacturing advantages of plastic while adding the optical correction capabilities of diffractive structures, achieving both cost reduction and performance maintenance

Inventive Principle:

Principle #40Composite materials

3Manufacturing precision

If more lenses are added to improve aberration correction, then aberration correction capability improves, but the imaging lens becomes larger and less compact

Engineering Contradiction:

Improveaberration correction capabilityVSAvoidimaging lens compactness

Core Design Contradiction:

Manufacturing precisionVSVolume of moving object

Solution Approach 1:

The patent merges multiple functions into a single lens element by forming a diffractive optical surface on one of the lenses. This single lens simultaneously provides focusing power and chromatic aberration correction, eliminating the need for separate correction lenses and thereby reducing the overall lens volume and improving compactness

Inventive Principle:

Principle #5Merging (Combining)

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 effectively corrects chromatic aberration and other types of aberrations, achieving a compact high-performance imaging lens with a small F-value, suitable for high-density image pickup devices like mobile phones, while reducing material costs through the use of plastic lenses.

Implementation Method 1

a diffractive optical surface with a chromatic aberration correction function is formed on one of the surfaces from the object side surface of the first lens to the object side surface of the second lens

Methodology Applied

Scientific EffectDiffraction: Diffraction

Data Source

PatentUS9535238B2Imaging lens

Publication Date: 2017.01.03 TOKYO VISIONARY OPTICS CO LTD

AI summary

A compact imaging lens suitable for a high pixel density image pickup device which properly corrects chromatic aberration and other types of aberrations and ensures high image quality, low f-number, and low cost. A first lens, second lens, third lens, fourth lens, and fifth lens are arranged in order from the object side and both sides of all the lenses are aspheric surfaces and a diffractive optical surface with a chromatic aberration correction function is formed on one of the surfaces from the object side surface of the first lens to the object side surface of the second lens and on one of the surfaces from the object side surface of the third lens to the object side surface of the fifth lens. All the lenses are made of a plastic material.