Optical System Evaluation with Wavefront and Off-Axis MTF Testing

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Solution Overview

Problem

Existing methods for evaluating optical performance of image pickup optical systems are limited in their ability to measure various aberrations and require adjustments for different specifications, such as angles of view and sensor sizes, leading to inefficiencies in measurement accuracy and flexibility.

Innovation Solution

An optical apparatus and evaluation method that utilizes a combination of a ring light source and a laser light source, along with a Shack-Hartmann sensor and intensity sensor, to measure on-axis transmitted wavefronts and off-axis modulation transfer functions (MTFs) of optical systems, allowing for flexible evaluation of optical performance across different specifications.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Device complexity

If a single light source and sensor configuration is used, then the device complexity is reduced, but the adaptability to different optical system specifications (angles of view, sensor sizes) deteriorates

Engineering Contradiction:
Improvemeasurement system configurationVSAvoidadaptability to different optical system specifications
Core Design Contradiction:
Device complexityVSAdaptability or versatility

Solution Approach 1:

The patent implements a universal measurement system that can evaluate multiple types of optical systems (different angles of view, sensor sizes) using a single apparatus. The system achieves this by incorporating both a ring light source and a laser light source, along with sensors positioned to measure both on-axis and off-axis wavefronts, enabling the same device to adapt to various optical specifications without requiring reconfiguration.

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

2Measurement precision

If multiple sensors and light sources are used to measure various aberrations, then the measurement precision is improved, but the device complexity increases

Engineering Contradiction:
Improveaberration measurement accuracyVSAvoidnumber of sensors and light sources
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The patent combines multiple measurement capabilities into a unified system. Specifically, it merges the ring light source (for illuminating the entire field) and the laser light source (for on-axis measurements) into a single apparatus, and integrates multiple sensors (intensity sensor and wavefront sensor) to simultaneously or sequentially measure different aberration types. This consolidation achieves comprehensive aberration measurement while maintaining a compact, integrated device structure.

Inventive Principle:
Principle #5Merging (Combining)

3Adaptability or versatility

If the sensor and light source positions are changed for different specifications, then the adaptability is improved, but the measurement time and operation complexity increase

Engineering Contradiction:
Improvemeasurement flexibility for different specificationsVSAvoidtime required for position adjustments
Core Design Contradiction:
Adaptability or versatilityVSLoss of time

Solution Approach 1:

The patent pre-positions multiple light sources and sensors to cover various measurement requirements simultaneously. The ring light source and laser light source are both positioned to illuminate different field regions, and multiple sensors are placed to detect on-axis and off-axis wavefronts without requiring physical repositioning. This preliminary arrangement of measurement components enables the system to evaluate different optical specifications immediately without time-consuming adjustments.

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

Enables accurate and efficient evaluation of optical performance, including aberrations like astigmatism, coma, and spherical aberration, across various optical systems with different angles of view and sensor sizes, enhancing measurement flexibility and accuracy.

Implementation Method 1

a wavefront sensor acquires a transmitted wavefront

Methodology Applied
Scientific EffectWavefront sensing:

Implementation Method 2

an intensity sensor receives the light

Methodology Applied
Scientific EffectLight intensity detection:

Implementation Method 3

light emitted from a light emitting system is transmitted through the target optical system

Methodology Applied
Scientific EffectLight transmission:

Data Source

PatentEP4151976B1Optical apparatus, evaluation apparatus, evaluation method, and manufacturing method of optical system
Publication Date: 2025.11.05 CANON KK
  • EP4151976B1 patent drawingFigure 1~2
  • EP4151976B1 patent drawingFigure 3~4D
  • EP4151976B1 patent drawingFigure 5~6

AI summary

An optical apparatus includes a first light source, a second light source, a chart, an optical system, and a light receiving system. The chart is configured to guide light emitted from the first light source to a target optical system. The optical system is configured to form a point image by using light emitted from the second light source. The light receiving system is configured to receive first light emitted from the chart via the target optical system and second light emitted from the point image via the target optical system. The first light and the second light enter different positions of the target optical system.