Wavelengths of Light, Part 2
ovitWe discussed lighting in general terms in the last issue.
We have been experimenting with various wavelengths of lighting in our company.
Ultraviolet light is also available,
In terms of visible light, red, green, blue, white, etc.
So, in conclusion,
Basically, white light is fine.
Of course, it depends on the defects you want to see,
(1) Due to color difference, such as foreign matter adhesion, discoloration, etc.
(2) Items with changes in surface roughness, such as scratches, dents, unevenness, etc.
The two main categories are
For ①, scattered light
For (2), direct light
It is common to use
Why is a visual inspection necessary?
See it in natural light (scattered light) conditions for a normal person,
It's the differences that bother me,
In the end, it is only necessary to inspect under white light conditions that include a variety of wavelengths.
This is why (1) is white light is sufficient.
For (2), if you move the object,
It can suddenly become dazzling, or conversely, it can become dark.
See how the observed point of view of the object changes.
I think people are concerned.
So it's not about wavelengths or colors.
The direction of light is the problem.
In most cases, visual inspections are performed under white fluorescent light while moving hands,
(2) I think there is no problem with white light as well.
I am a regular reader with great interest.
I can relate to what you have said this time as well.
In my experience, I have tried many different types of light and natural light seems to be the most comprehensive and well-balanced.
However, since Led light has a long life span, a new series is usually introduced at the time of renewal, so I have experienced that even white light from the same manufacturer has changed from the yellowish light of a long time ago to a whiter (bluish) color, and the defects that were detectable before are no longer detectable.
Although the Led may have evolved to be more powerful and sophisticated, it is not always possible to say that the newest one matches the past situation.
It is necessary not only to blindly trust new things, but also to be aware of changes as a user.
My apologies.
Thank you for your comment.
If the illumination light becomes stronger, the amount of light irradiating the defect will change, so the luminance value of the defect will increase and the area of the defect will decrease,
The area of the defect should be smaller.
It is quite understandable that it becomes invisible.
High-power LEDs are effective for high-speed inspections, such as using strobe light emission,
However, if constant light emission is considered, it may only obscure defects.
I sympathized with the need for understanding of those who use the product, as you said.
Thank you very much.