Imaging Optical System Nonuniform Light Distribution Correction

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Solution Overview

Problem

Existing imaging optical systems face challenges in addressing the reduction in peripheral light amount due to the optical characteristics of lenses, which leads to nonuniformity in light distribution, and existing solutions either rely on signal processing that amplifies noise or do not adequately correct for the lens's optical characteristics.

Innovation Solution

An imaging optical system is designed with an optical member, such as a gradation ND filter, where the light transmittance value is higher in the peripheral portions than in the central portions, optically correcting the nonuniformity in light distribution rather than relying on signal processing.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the aperture of the lens is increased to solve small aperture diffraction, then the diffraction problem is resolved, but the peripheral light amount decreases due to optical characteristics of the lens

Engineering Contradiction:

Improveimage qualityVSAvoidperipheral light amount

Core Design Contradiction:

ReliabilityVSIllumination intensity

Solution Approach 1:

The patent applies local quality by using a condenser lens with non-uniform light transmittance distribution, where the central portion has higher transmittance and the peripheral portion has lower transmittance. This compensates for the lens's optical characteristic that causes peripheral light amount reduction, thereby maintaining uniform illumination across the imaging surface while allowing the aperture to be increased for diffraction correction.

Inventive Principle:

Principle #3Local quality

2Illumination intensity

If signal processing amplification is used to correct peripheral light amount reduction, then the illumination uniformity is improved, but noise and flaws are emphasized

Engineering Contradiction:

Improveperipheral light amount uniformityVSAvoidnoise amplification

Core Design Contradiction:

Illumination intensityVSObject-generated harmful factors

Solution Approach 1:

The patent replaces the signal processing system (electrical/electronic correction method) with an optical system (condenser lens with specific transmittance distribution). By correcting the peripheral light amount reduction through optical design rather than post-capture signal amplification, the method avoids emphasizing noise and flaws while achieving illumination uniformity.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

3Manufacturing precision

If pixel size is reduced to increase pixel resolution, then the imaging resolution is improved, but small aperture diffraction becomes more pronounced

Engineering Contradiction:

Improvepixel resolutionVSAvoidimage quality

Core Design Contradiction:

Manufacturing precisionVSReliability

Solution Approach 1:

The patent applies preliminary action by correcting the peripheral light amount reduction before the light reaches the imaging surface, using a condenser lens with optimized transmittance distribution. This preliminary optical correction enables the use of smaller pixels for high resolution without suffering from small aperture diffraction effects, as the illumination uniformity is established prior to image capture.

Inventive Principle:

Principle #10Preliminary action

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 solution optically corrects the nonuniformity in light distribution caused by lens optical characteristics, reducing the need for signal processing corrections that can introduce noise, and allows for the miniaturization of pixels, enabling high-definition imaging while reducing the number of lenses and associated costs.

Implementation Method 1

an optical member, in which the optical member is configured such that a light transmittance value at least in a peripheral portion is larger than a light transmittance value in a central portion

Methodology Applied

Scientific EffectLight absorption: Absorption (EM radiation)

Data Source

PatentUS11156751B2Imaging optical system, camera module, and electronic device

Publication Date: 2021.10.26 SONY SEMICON SOLUTIONS CORP

AI summary

An imaging optical system according to the present disclosure includes: a lens; and an optical member, in which the optical member is configured such that a light transmittance value at least in a peripheral portion is larger than a light transmittance value in a central portion. Furthermore, a camera module according to the present disclosure includes the imaging optical system of the present disclosure. Furthermore, an electronic device according to the present disclosure includes a solid-state imaging element and the imaging optical system of the present disclosure.