Inspection Device for Image Pickup Apparatus Using Refractive Index Matching
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Solution Overview
Problem
In-liquid endoscopes face optical defects such as vignetting and reflection issues during in-gas observation due to differences in refractive indices between liquid and gas, making it difficult to inspect for dust or delamination on the optical adhesive surfaces.
Innovation Solution
An inspection device with an angle-of-view conversion optical member made of a translucent material with a predetermined refractive index, used in conjunction with a test chart, allows for image pickup and illumination to simulate in-liquid conditions during in-gas inspection, ensuring the entire surface is illuminated and defects are visible.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If inspection is performed in gas environment, then inspection can be conducted without soaking in liquid, but vignetting portion is generated making it impossible to confirm fine dirt or delamination
Solution Approach 1:
A liquid-filled inspection chamber is introduced as an intermediary medium between the image pickup apparatus and the inspector. The liquid fills the chamber and contacts the distal end optical member, creating an in-liquid inspection environment without requiring the apparatus itself to be soaked in liquid. This allows the entire light-receiving area to be illuminated and inspected for defects such as dust and delamination.
Solution Approach 2:
The refractive index parameter of the inspection environment is changed by introducing liquid (water or other liquids) into the inspection chamber. This parameter change transforms the optical conditions from gas-phase (causing vignetting) to liquid-phase (providing uniform illumination), enabling effective defect detection across the entire image pickup area.
2Reliability
If image pickup apparatus is soaked in liquid for inspection, then optical defects can be reduced, but inspection complexity and preparation time increase
Solution Approach 1:
The inspection system is segmented into a separate liquid-filled inspection chamber that can be independently prepared and controlled. This allows the image pickup apparatus to remain dry and protected while the liquid environment is created only in the inspection chamber, simplifying the overall system and reducing preparation complexity.
Solution Approach 2:
The liquid-filled chamber serves as an intermediary that provides the necessary liquid environment for optimal optical inspection without requiring the image pickup apparatus itself to be soaked in liquid. This separation reduces the complexity of handling and preparation requirements.
3Quantity of substance
If refractive index difference between liquid and gas is considered, then optical image formation changes, but inspection accuracy is compromised in gas environment
Solution Approach 1:
The refractive index parameter of the inspection medium is changed from gas (air) to liquid by filling the inspection chamber with liquid. This parameter change eliminates the vignetting effect and ensures that light covers the entire light-receiving area uniformly, improving inspection accuracy across the full image pickup area.
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 effective inspection of image pickup apparatuses in gas environments without soaking them in liquid, allowing for the detection of dust and delamination on optical adhesive surfaces, mimicking the in-liquid observation state for accurate defect identification.
Implementation Method 1
an angle-of-view conversion optical member made of a translucent member having a predetermined refractive index
Implementation Method 2
the chart surface of the reflection chart is irradiated with illumination light that is emitted from the illumination portion and enters the angle-of-view conversion optical member from a side surface located between the first surface and the second surface
Data Source
AI summary
An inspection device for image pickup apparatus includes: an image pickup apparatus including an image pickup device inside a first lens barrel; an angle-of-view conversion optical member made of a translucent resin member and including a first surface and a second surface that is an opposite surface of the first surface, the first surface being configured to closely contact a surface of a distal end lens, the surface of the distal end lens being exposed outside of the first lens barrel; a test chart including a chart surface provided so as to closely contact the second surface, and an image of the chart surface being picked up by the image pickup apparatus through the angle-of-view conversion optical member, and an illumination instrument that illuminates the chart surface.