About Pinholes and Fractures

About Pinhole Detection

Detecting Pinholes in Cavity Sidewalls




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About Pinhole Detection

Detecting pinholes in high barrier foils and laminates is essentially a "back lighting" technique. That is, one side of the material to be inspected is illuminated with a light source and the other side has a device for detecting any light emerging from the material. An example of the technique is a person in a dark room holding a piece of material with a pinhole in front of a bright light source. The person looking for any light penetrating the material is the "light detecting device". 

Automatic pinhole detecting systems like the Alumivision are obviously more complicated than the preceding description. The Alumivision is capable of detecting very small amounts of light emanating from holes tens-of-microns or less in size. It does so at production machine speeds and on a continuous basis. This in done in an environment that has a level of ambient light that is very large in comparison to the light level being detected.

Various schemes are employed in various pinhole detectors, but essentially, they all have a light source and a means to detect the light penetrating the material under inspection. See drawing below.