Optically Absorptive Grating for Stray Light Reduction

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Solution Overview

Problem

Stray light within camera modules can cause lens flares and other artifacts in captured images, and existing technologies have not effectively mitigated these issues.

Innovation Solution

Incorporating an optically absorptive grating with an array of protrusions into the camera module, which absorbs incident light and spreads unabsorbed reflected light across multiple directions, thereby reducing the amount of stray light that reaches the image sensor.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Use of energy by moving object

If light reflects off surfaces within the camera module, then the optical component can redirect light towards the image sensor, but stray light causes lens flares and artifacts in captured images

Engineering Contradiction:

Improvelight redirection efficiencyVSAvoidstray light impact

Core Design Contradiction:

Use of energy by moving objectVSObject-affected harmful factors

Solution Approach 1:

The patent applies this principle by converting the harmful stray light into beneficial reflected light through the optically absorptive grating. The grating's protrusions reflect stray light that would otherwise cause lens flares and artifacts, redirecting it toward the image sensor to contribute usefully to image capture rather than degrading quality

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

Solution Approach 2:

The patent applies this principle by creating localized optically absorptive regions on the optical component surface. The grating structure provides different optical properties at different locations - the protrusions have specific reflectivity characteristics while the valleys have absorptive characteristics, allowing selective manipulation of light paths in different local areas to reduce stray light while maintaining overall light redirection efficiency

Inventive Principle:

Principle #3Local quality

2Object-affected harmful factors

If an optically absorptive grating is added to the camera module, then stray light is reduced, but the device complexity increases

Engineering Contradiction:

Improvestray light impactVSAvoidcamera module structure

Core Design Contradiction:

Object-affected harmful factorsVSDevice complexity

Solution Approach 1:

The patent applies this principle by merging the stray light mitigation function directly into the existing optical component surface. The optically absorptive grating is formed as an integral part of the optical component rather than being a separate attached element, combining the optical component's light redirection function with the grating's stray light absorption and reflection functions into a single unified structure

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The patent applies this principle by changing the surface parameters of the optical component - specifically the refractive index distribution and surface topology - to create the optically absorptive grating structure. By modifying the optical properties and geometric parameters of the existing component rather than adding entirely new elements, the patent reduces stray light while minimizing increases in device complexity

Inventive Principle:

Principle #35Parameter changes

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 optically absorptive grating effectively reduces the impact of stray light on image quality by absorbing and diffusing stray light, thereby minimizing lens flares and other artifacts in captured images.

Implementation Method 1

an optically absorptive grating that is configured to absorb light

Methodology Applied

Scientific EffectLight absorption: Absorption (EM radiation)

Implementation Method 2

spread reflected light that is not absorbed by the absorptive grating

Methodology Applied

Scientific EffectLight reflection: Reflection

Implementation Method 3

The grating includes be an array of protrusions

Methodology Applied

Scientific EffectLight diffraction: Diffraction

Implementation Method 4

light entering the optical assembly reflects off a surface of the prism via total internal reflection

Methodology Applied

Scientific EffectTotal internal reflection: Total Internal Reflection

Data Source

PatentUS20250123428A1Camera modules with micro-scale optically absorptive gratings

Publication Date: 2025.04.17 APPLE INC

AI summary

Embodiments described herein relate to camera modules that incorporate an optically absorptive grating that is positioned and designed to reduce the impact of stray light on images captured by the camera modules. Specifically, the optically absorptive grating is configured to absorb light that is incident on the optically absorptive grating. The optically absorptive grating includes an array of protrusions, and in some instances may be part of a grating assembly that is coupled to an optical component.