Laser light interference on liquid metal. why?

[bizzder]

I wanted to make tiny movements of the Earth visible by reflecting laser light off liquid gallium metal. It did produce nice reflections on my wall, showing dramatic wobbles of very tiny movements of the liquid gallium. It did however produce light interference patterns which I cannot explain. Simply reflecting the laser light on the wall with a mirror doesn't produce this.

How is it that a metal can produce this? Metals are very nice examples of how it's combined particles behave individually because of purity (through amplification?) Is this a good example of the laser light interacting with gallium atoms on a quantum scale? How does this work? I think it's quite interesting!

 

[Bill_K]

Yes I agree, it's quite interesting! Is it really an interference pattern? You know, if you reflect light off an irregular surface like the surface of water, you'll see a moving pattern of light and dark too, but this is focusing and defocusing caused by ripples on the water and changing curvature of the surface. I'm wondering if that's what you're seeing here.

 

[bizzder]

They are very distinct and well defined lines, with perfect spacings between. At some points, these lines overlap, and create a dot pattern, which I think it's proof that his is light interference!

 

[poor mystic]

Perhaps impurities in the Gallium are causing a microscopic lumpiness in the surface of the droplet? That would give several reflections a chance to be cast onto the one point on your wall.
If this is so you might be able to find a way to push the impurities around and so change the pattern displayed on your wall.

 

[SpectraCat]

They are very distinct and well defined lines, with perfect spacings between. At some points, these lines overlap, and create a dot pattern, which I think it's proof that his is light interference!

Can you post a photo? And give some indication of the angle of incidence between the beam and the surface, as well as the distance to the wall? That should allow you to figure out the dimension of the features that are producing the diffraction pattern.