I was messing around with my laser and razors again and I noticed this reflection pattern when I passed one blade partway through the beam.

This picture has the razor at about a 45 degree angle perpendicular to the beam. The laser is hitting the blade body, the sharpened inclined edge, and the wall far behind it.



Why is the reflection from the sharpened flat part curved?!

This one is when the razor is still angled down but also angled horizontally relative to the ground.



Why in the world does it do that?!

Well, is the blade straight? because it might be a reflection of a rounded blade. show me a picture how it looks like in daylight

This is with another razor, too.

It must have something to do with the surface because it's got grinding lines.

The shiny surface of the razor blade doesn't reflect like that, but a scissors blade (with obvious grinding lines) reflects like that on any part of the surface.

It's in a parabolic shape, though, which is cool.

Hey, I replicated your experiment, and got the curve, also I noticed that when I shone the laser along edge lengthwise, it actually formed a complete ring! Changing the angle of incedence created smaller and larger rings. I can't fathom an answer!

It's so strange! hahaha This is going to bother me for the rest of the week, at least!

Show a picture of that complete ring, if you could!

Hi Pr0pensity and Denison06379,

I "think" you may have created a "dislocation" and excited some high order orbital angular momentum modes in light with that "edge". This phenomenon is usually called "Twisted Light". It is an interesting "diversion" and it has some strange properties. For instance you can cause small objects to spin with it and you can use this as "optical tweezers" under the right conditions. I am unsure this is what you have but it "looks" like you may have it there in some form.

Here is a grating that surely will excite orbital optical angular momentum...

It you create this image at the right scale on a good "photocopier" on OHP film, with a decent CW laser, you will be able to create those vortices shown here...
Light Beams in High-Order Modes
Homemade Vortices - Generating your Own Doughnuts!

Geometric Phase Associated with Mode Transformations
These suckers can exert forces transverse to the direction of propagation and "grasp" stuff and "spin" them etc. that is if they are small enough. They are more useful if they are small...

Now that you may have a handle on this you may be able to get this to be useful... yours certainly looks a bit different. The important bit about this is to aim the laser at the "dislocation" at the center. There are other gratings with a three pronged fork at the center. I "think" we are dealing with "optical berry phase".

There is an associated "Parallel Transport" Java Applet that shows some interesting effects of parallel transport of vectors on a surface of a sphere...
Spherical Geometry Demo
Twisted Light Communication

Cheers

WOW!

That is SO COOL!

I'm trying to come up with a physics research project and this looks really, really cool!!!

I can't thank you enough!


I bet the razor blade has imperfections in the grinding like that of the diffraction grating. This is very puzzling and I will look further at manipulating the grating to see how it affects the diffraction pattern.

Would it be alright if sometime in the future I contacted you if I had questions?

forgot to log in... i'm at school. This is pr0pensity btw

i believe its also called "knife edge defraction" . amatuer radio ops use this to "bend" radio waves of higher frequencies over the horizon, or mountain ranges.

Hi Pr0pensity and Blistered,