If you don't mind, I'll post the trig diagram later, probably tomorrow. I have part 3 ready to demonstrate.

So let's consider the case when the tubes or fibers are not opaque, but partially transparent.

The attached diagram shows how light has to pass through the cloth at various angles.

When the angle of incidence is 0, the distance that the light must travel is shortest. In fact, it is precisely the thickness of the cloth. This is the first case.

When the angle increases, the distance increases. You can see that in the second case, where the angle is 45 degrees, the distance that the light must pass through is 1.414 (sqrt of 2) times the original distance.

In the third case, at 60 degrees, the distance is twice the original distance.

Now the question is, what effect does this have?

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