Dynamic Aperture Control for Optical Measurement Resolution

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Solution Overview

Problem

Conventional measuring apparatuses for optical characteristics, such as diffusion and gloss, face a trade-off between angular resolution and light quantity, with pinhole sources providing high resolution but low luminous sensitivity, and aperture sources offering better light but compromised angular resolution.

Innovation Solution

A measuring apparatus employing a Wiener filter to determine the coefficient based on the degree of diffusion, allowing for optimal BRDF measurement by varying the Wiener filter coefficient in accordance with the sample's diffusion characteristics, thereby enhancing angular resolution without sacrificing light quantity.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If a pinhole serves as a secondary light source, then the angular resolution of the diffusion characteristic is improved, but the quantity of light and luminous sensitivity deteriorate

Engineering Contradiction:
Improveangular resolutionVSAvoidquantity of light
Core Design Contradiction:
Measurement precisionVSIllumination intensity

Solution Approach 1:

The patent changes the parameter of the secondary light source from a fixed pinhole to a variable aperture whose size can be dynamically adjusted. By controlling the aperture size according to the measurement requirements and sample characteristics, the system can optimize between angular resolution (smaller aperture) and light quantity (larger aperture), resolving the contradiction between these two parameters.

Inventive Principle:
Principle #35Parameter changes

2Illumination intensity

If the angle of the aperture in the aperture plate is increased, then the quantity of light is improved, but the angular resolution of the obtained optical characteristic deteriorates

Engineering Contradiction:
Improvequantity of lightVSAvoidangular resolution
Core Design Contradiction:
Illumination intensityVSMeasurement precision

Solution Approach 1:

The patent implements a dynamic aperture control mechanism where the aperture size is not fixed but can be adjusted during the measurement process. This dynamic adjustment allows the system to adapt the aperture angle according to the specific measurement needs, enabling optimization of both light quantity and angular resolution depending on the measurement conditions.

Inventive Principle:
Principle #15Dynamics

3Adaptability or versatility

If a general-purpose measuring apparatus is used to obtain multiple indices from diffusion characteristic, then the versatility is improved, but the measurement precision of individual optical characteristics may deteriorate due to the trade-off between angular resolution and light quantity

Engineering Contradiction:
ImproveversatilityVSAvoidoptical characteristic measurement precision
Core Design Contradiction:
Adaptability or versatilityVSMeasurement precision

Solution Approach 1:

The patent creates a universal measuring apparatus that can measure multiple optical characteristics (diffusion characteristic, specular gloss, haze, image clarity) through a single system with a controllable aperture. The aperture control mechanism serves all measurement functions, allowing the system to maintain high measurement precision across different types of measurements by dynamically adjusting the aperture according to each specific measurement requirement.

Inventive Principle:
Principle #6Universality (Multi-functionality)

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 apparatus achieves improved angular resolution of optical characteristics by dynamically adjusting the Wiener filter coefficient, resulting in accurate BRDF measurements that closely match pinhole performance while maintaining sufficient light sensitivity.

Implementation Method 1

an optical system that includes a light source, an aperture unit having an aperture, and condenser lenses. The optical system projects light onto a sample and receives light via the sample

Methodology Applied
Scientific EffectLight transmission and reflection: Reflection

Implementation Method 2

condenser lenses configured to receive specular reflection light produced as light from the condenser lens is specularly reflected by the sample

Methodology Applied
Scientific EffectLight focusing: Lens

Data Source

PatentEP3093650B1Measuring apparatus, measuring method, and program
Publication Date: 2021.04.07 CANON KK
  • EP3093650B1 patent drawingFigure 1A~1B
  • EP3093650B1 patent drawingFigure 2
  • EP3093650B1 patent drawingFigure 3

AI summary

A measuring apparatus includes an optical system (102, 103) configured to project light onto a sample (2) and to receive light via the sample, an imaging device (3) configured to take an image of a light source (101) via the optical system, and a processor (4) configured to obtain an optical characteristic of the sample based on an output of the imaging device. The processor is configured to determine a coefficient of a Wiener filter based on one of the image and a Fourier transform thereof and corresponding one of the light source (an aperture in an aperture unit (101)) and a Fourier transform thereof, and obtain the optical characteristic based on the Wiener filter of which the coefficient has been determined, a Fourier transform of the image, and a Fourier transform of the light source.