Quote:
Originally Posted by TrevorW
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A bit of light reading! The best part was page 38 in bold.
Seriously though ...
I assume you are referring to my simple experiment and it is a valid point (diffraction).
I had thought about diffraction but assumed it would not be significant with the width of the laser beam.
If you do a torch test with a 2mm piece of wire across its face, it can be established that it will throw a shadow on the wall. Only a very bright torch will noticeably diffract light around the wire to reduce the shadow in the central region and this effect can be pretty much eliminated by holding the wire further from the torch face. The emergent beam on my pointers are around 2mm and diverge gradually over distance. So, using the wire as a control, it can still be established the laser beam throws no shadow.
Regards, Rob.