Aspheric Plastic Optical Lens Assembly for IR Leakage Control

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Solution Overview

Problem

Conventional optical lens assemblies using blue glass for infrared filtering are costly, difficult to miniaturize, and suffer from light leakage and reflection issues, especially at large incident angles, leading to color shift and reduced imaging quality.

Innovation Solution

An optical lens assembly with at least three plastic lens elements, each with an infrared filtering coating having two different refractive indices and an aspheric surface, combined with long-wavelength absorbing materials, to control incident angles and transmittance, reducing the number of elements and minimizing reflections.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Device complexity

If a planar element with infrared filtering coating is used, then the number of elements can be reduced, but light leakage and reflection occur at large incident angles

Engineering Contradiction:

Improvenumber of elementsVSAvoidlight leakage and reflection

Core Design Contradiction:

Device complexityVSObject-affected harmful factors

Solution Approach 1:

The patent applies aspheric surfaces to the plastic lens elements instead of planar surfaces. The aspheric design allows for better control of light paths at various incident angles, reducing off-axis light leakage and reflection while maintaining the infrared filtering function with fewer elements.

Inventive Principle:

Principle #14Spheroidality (Curvature)

Solution Approach 2:

The patent changes the physical parameters of the lens elements by using plastic materials with specific refractive indices and incorporating long-wavelength absorbing materials. This allows the plastic elements to achieve infrared filtering performance comparable to blue glass while enabling aspheric designs that control light paths more effectively.

Inventive Principle:

Principle #35Parameter changes

2Reliability

If blue glass is used for infrared filtering, then imaging quality is maintained, but manufacturing cost increases and miniaturization becomes difficult

Engineering Contradiction:

Improveimaging qualityVSAvoidmanufacturing cost and miniaturization

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

The patent replaces expensive blue glass with plastic lens elements that can be manufactured more cheaply through injection molding. The plastic material allows for cost-effective production while maintaining the necessary optical properties through careful selection of refractive indices and incorporation of absorbing materials.

Inventive Principle:

Principle #27Cheap short-living objects (Disposable)

Solution Approach 2:

The patent uses composite plastic materials that combine base plastic with long-wavelength absorbing materials to achieve infrared filtering properties. This composite approach allows plastic elements to replace blue glass while maintaining imaging quality and enabling miniaturization.

Inventive Principle:

Principle #40Composite materials

3Reliability

If the number of lens elements is increased to improve imaging quality, then aberration correction improves, but device complexity and size increase

Engineering Contradiction:

Improveimaging quality and aberration correctionVSAvoidnumber of elements and size

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent combines multiple functions into fewer plastic lens elements. The aspheric surfaces and incorporated absorbing materials allow single elements to perform both imaging and infrared filtering functions, reducing the total number of elements needed while maintaining aberration correction capability.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The aspheric design of the plastic lens elements provides superior aberration correction compared to traditional spherical elements. The variable curvature of aspheric surfaces allows for better control of light paths, enabling high imaging quality with fewer elements.

Inventive Principle:

Principle #14Spheroidality (Curvature)

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 effectively minimizes light leakage, reduces manufacturing costs, and enhances imaging quality by controlling incident angles and transmittance, allowing for a more compact and efficient optical lens assembly.

Implementation Method 1

reflective coating technique, which leads to interference, will cause reflection and light-leakage

Methodology Applied

Scientific EffectReflection: Reflection

Implementation Method 2

At least one of the optical lens elements includes a long-wavelength absorbing material

Methodology Applied

Scientific EffectAbsorption (EM radiation): Absorption (EM radiation)

Data Source

PatentUS12405411B2Optical lens assembly, imaging apparatus and electronic device

Publication Date: 2025.09.02 LARGAN PRECISION

AI summary

An optical lens assembly includes at least three optical lens elements. At least one of the optical lens elements includes an infrared filtering coating, the optical lens element including the infrared filtering coating is made of a plastic material, the infrared filtering coating is arranged on an object-side surface or an image-side surface of the optical lens element, a surface of the optical lens element including the infrared filtering coating is aspheric, and the infrared filtering coating includes at least two different refractive indices. At least one of the optical lens elements includes a long-wavelength absorbing material, and the optical lens element including the long-wavelength absorbing material is made of a plastic material.