Optical System Angle-Dependent Colorimetric Error Reduction

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Solution Overview

Problem

Existing optical systems for luminance and colorimeters face challenges with measurement errors due to directivity and angle of incidence, particularly when using interference filters, which result in high sensitivity to light beam orientation and limited flexibility in filter design.

Innovation Solution

The optical system employs a first diffusion member to scatter the luminous flux, followed by a series of interference filters with predetermined transmittance characteristics, and additional second diffusion members to adjust for angle of incidence, ensuring stable light reception sensitivity regardless of the measurement object's position or rotation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If interference filters are used for colorimetric optical systems, then the degree of freedom in filter design and light transmission efficiency are improved, but the sensitivity to angle of incidence increases causing measurement errors

Engineering Contradiction:
Improvefilter design flexibilityVSAvoidmeasurement error
Core Design Contradiction:
Adaptability or versatilityVSMeasurement precision

Solution Approach 1:

A diffusion plate is introduced as an intermediary component between the measurement object and the interference filters. This diffusion plate scatters the incident light to create a divergent beam with various angles of incidence, thereby compensating for the angle sensitivity of interference filters and enabling accurate colorimetric measurements while maintaining the design flexibility advantages of interference filters.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Adaptability or versatility

If light absorption type color filters are used, then the filter design has limited flexibility, but the transmittance is low causing significant light loss

Engineering Contradiction:
Improvefilter design flexibilityVSAvoidlight loss
Core Design Contradiction:
Adaptability or versatilityVSLoss of energy

Solution Approach 1:

The patent transitions from light absorption type filters to interference type filters, changing the fundamental working principle from absorption to interference. This parameter change enables high design flexibility through adjustable spectral characteristics while achieving high transmittance and minimal light loss, as interference filters reflect unwanted wavelengths rather than absorbing them.

Inventive Principle:
Principle #35Parameter changes

3Measurement precision

If bundle fiber is used to reduce directivity measurement error, then measurement accuracy improves, but the cost increases and directivity error remains

Engineering Contradiction:
Improvemeasurement errorVSAvoidsystem complexity
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The patent replaces the expensive and complex bundle fiber system with a simpler, more cost-effective diffusion plate. The diffusion plate achieves the necessary light distribution function without the high cost and manufacturing complexity of bundle fibers, providing a practical and economical solution for reducing directivity measurement errors.

Inventive Principle:
Principle #27Cheap short-living objects (Disposable)

4Device complexity

If diffusion plate is used instead of bundle fiber, then cost is reduced, but directivity measurement error increases

Engineering Contradiction:
Improvesystem simplicityVSAvoidmeasurement error
Core Design Contradiction:
Device complexityVSMeasurement precision

Solution Approach 1:

The patent combines the diffusion plate with interference filters, changing the optical parameters of the system. The interference filters provide sharp spectral selection that compensates for the angular spread introduced by the diffusion plate, thereby maintaining measurement precision while keeping the system simple and cost-effective.

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

This configuration reduces measurement errors caused by angle of incidence and maintains high stability and flexibility in transmittance characteristics, while minimizing light loss and preserving the advantages of interference filters.

Implementation Method 1

a first diffusion member on which a luminous flux from a measurement object is made incident

Methodology Applied
Scientific EffectDiffusion: Diffusion

Implementation Method 2

a plurality of sets of interference filters which are arranged in a row at an outgoing end side of the first diffusion member, receive the outgoing light scattered by the first diffusion member as incident light, and transmit the incident light with mutually different predetermined transmittance characteristics

Methodology Applied
Scientific EffectInterference: Interference

Implementation Method 3

second diffusion members which are arranged before the interference filters

Methodology Applied
Scientific EffectDiffusion: Diffusion

Data Source

PatentEP2562520B1Optical system for measurements, and luminance colorimeter and colorimeter using same
Publication Date: 2019.05.29 KONICA MINOLTA OPTICS
  • EP2562520B1 patent drawingFigure 1
  • EP2562520B1 patent drawingFigure 2
  • EP2562520B1 patent drawingFigure 3

AI summary

In a measuring probe 40, a measuring beam is diffused by a first diffusion plate 19, and when received by a plurality of light-receiving sensors 13B, 14B, 15B via a plurality of interference filters 13A, 14A, 15B, the measuring beam is made incident on the interference filters 13A, 14A, 15B via second diffusion plates 13C, 14C, 15C. Those interference filters 13A, 14A, 15B are formed such that transmittance characteristics corresponding to a measurement parameter are obtained correspondingly to intensity distribution conditions for an angle of incidence of light incident on the interference filters 13A, 14A, 15B. Therefore, the measuring probe 40 can reduce the effect of displacement of the transmission characteristic caused by the angle of incidence, while using the interference filters 13A, 14A, 15B.