[Bored chemist]

Have you seen any literature describing single slit or double slit experiment where the light source is not at normal angle to the aperture?

Essentially all of them.
The beam is almost always divergent, so the top and bottom of it are not perpendicular to the slit.
It doesn't seem to matter much.

[hamdani yusuf (OP)]

Here is a diagram of double slit experiment.

If we use particle model, what's the effect of removing the plates above and below the middle plate?
The middle plate alone should be enough to split the trajectory of the photons.

[hamdani yusuf (OP)]

Have you seen any literature describing single slit or double slit experiment where the light source is not at normal angle to the aperture?

Essentially all of them.
The beam is almost always divergent, so the top and bottom of it are not perpendicular to the slit.
It doesn't seem to matter much.

Can you show me one?

[alancalverd]

Consider the polychromatic Newton's rings seen when white light self-interferes  by reflection from plane and convex surfaces. It's all delightfully divergent.

Apparently Newton (Trinity, Cambridge) favored the corpuscular theory whilst his enemy Hooke (Gresham, London) was a wave man. I can't see how you can explain the rings with corpuscles, but Trinity College has produced  more Nobel prizewinners than France, so I'm probably out of  my depth here.

[Bored chemist]

Have you seen any literature describing single slit or double slit experiment where the light source is not at normal angle to the aperture?

Essentially all of them.
The beam is almost always divergent, so the top and bottom of it are not perpendicular to the slit.
It doesn't seem to matter much.

Can you show me one?

Can you show me one where the beam is not divergent?

For example the typical specification for  a HeNe laser of the type used in physics demos has a divergence of about 1 milliradian.

Since the beam is divergent the top and bottom of the bean can't simultaneously be perpendicular to a straight wire.

[hamdani yusuf (OP)]

Have you seen any literature describing single slit or double slit experiment where the light source is not at normal angle to the aperture?

Essentially all of them.
The beam is almost always divergent, so the top and bottom of it are not perpendicular to the slit.
It doesn't seem to matter much.

Can you show me one?

Can you show me one where the beam is not divergent?

For example the typical specification for  a HeNe laser of the type used in physics demos has a divergence of about 1 milliradian.

Since the beam is divergent the top and bottom of the bean can't simultaneously be perpendicular to a straight wire.

Ok. Now we agree that there's no publicized experiment on diffraction where the light beam from the source has deviation from normal by around 45 degrees or more.

[Bored chemist]

Have you seen any literature describing single slit or double slit experiment where the light source is not at normal angle to the aperture?

Essentially all of them.
The beam is almost always divergent, so the top and bottom of it are not perpendicular to the slit.
It doesn't seem to matter much.

Can you show me one?

Can you show me one where the beam is not divergent?

For example the typical specification for  a HeNe laser of the type used in physics demos has a divergence of about 1 milliradian.

Since the beam is divergent the top and bottom of the bean can't simultaneously be perpendicular to a straight wire.

Ok. Now we agree that there's no publicized experiment on diffraction where the light beam from the source has deviation from normal by around 45 degrees or more.

For a start, no, we can't agree about that- because nobody looked.
There may be published work in the field. How would we know?

Define "published"
I tried the experiment  earlier and it didn't seem to make any difference.
I am publishing that result here now.

If I get time I might set it up better at the weekend + get pictures.

I'm not claiming to be the first to have done it- as I said, anyone who looked through fine silk...

[hamdani yusuf (OP)]

Can we get easily observed interference pattern in single slit experiment, if the laser is 500 nm, the width of the slit is 50 mm, and distance from the screen is 5 m?

[hamdani yusuf (OP)]

Define "published"
I tried the experiment  earlier and it didn't seem to make any difference.
I am publishing that result here now.

you can put the hyperlink here so everyone can see the result. A picture worths a thousand words, so it clearly helps. Better yet, if it's a video, or moving pictures, so we can see from different perspectives, and information related to passing time is not completely removed, such as the case with still pictures.

[hamdani yusuf (OP)]

I'd like to remind you that this thread is meant to compare currently accepted theories with our observations. What are the results predicted by the mathematical models for a particular experimental setup? What is actually observed? Is there a discrepancy? Can we identify the cause of the discrepancy? Can it be removed by changing some aspect of the experimental setup?
Here are some experimental observations I uploaded to Youtube. I think you can easily reproduce them to make sure that they are not misleading tricks.

Investigation on Diffraction of light 4 : Non-diffractive obstacle

Investigation on Diffraction of Light 9 : Horizontally Tilted

Investigation on Diffraction of Light 10 : Vertically Tilted Obstacle

Investigation on Diffraction of Light 13 : Non-Diffractive slit; A Challenge to Huygen's Principle

[evan_au]

A reply to some old comments in this thread...

How do you split a single photon?

There are ways of doing it using non-linear optics. For conservation of energy, the two photons each have lower energy, with a total energy equal to the original photon.

You can also combine two photons into a single photon using non-linear materials, producing a green laser beam from an infra-red laser source.

But the double-slit experiment also works in a vacuum, ie using linear optics.

See: https://en.wikipedia.org/wiki/Nonlinear_optics#Frequency-mixing_processes

what would make (light) different from a gravitational wave?

One aspect that is very different is in how we detect them.
- Light power from a star follows an inverse square law, so if you double the sensitivity of your telescope (2xArea), you can detect a source 1.4x as far away, ie in a volume of space 2.8 times bigger.
- As I understand it, our current gravitational wave detectors do not detect power, but the amplitude of stress (power being proportional to the square of stress). That means they follow an inverse law (not inverse square law). If you double the sensitivity of your detector, you can detect an object twice as far away, ie in a volume of space 8 times bigger.

The electric-field amplitude of light from a star decreases proportional to distance, but as the power is the square of the amplitude, you get an inverse square law.

[hamdani yusuf (OP)]

See: https://en.wikipedia.org/wiki/Nonlinear_optics#Frequency-mixing_processes

The crystal is supposed to be macroscopic, and consists of many atoms. How can a single photon know where to go after interacting with it, instead of scattered at random direction?

[Bored chemist]

The QM  interpretation of things like Raman spectra, frequency mixing and doubling involve these.
https://en.wikipedia.org/wiki/Virtual_state

[acsinuk]

Photons need a full cubic volume of space to move through.  If there is an angle of deflection then real energy will be mixed with virtual/imaginary/quantum magnoflux light.

[Bored chemist]

Photons need a full cubic volume of space to move through.  If there is an angle of deflection then real energy will be mixed with virtual/imaginary/quantum magnoflux light.

helping.JPG (28.02 kB . 475x335 - viewed 2123 times)

[Colin2B]

Photons need a full cubic volume of space to move through.  If there is an angle of deflection then real energy will be mixed with virtual/imaginary/quantum magnoflux light.

Please refrain from posting new theories in the main section. Continuing to do so may result in limitations on your posting rights.

[Bored chemist]

 It's a rather warm day, so the idea of going down to the cellar and playing with a laser and a slit appealed to me.
Here's the rig. There's a screen off to the right.


slit expte 1 resized.jpg (96.48 kB . 707x317 - viewed 4042 times)

[Bored chemist]

And here is the diffraction pattern, as you would expect.

slit expte 3 resized.jpg (50.96 kB . 746x322 - viewed 2401 times)

[Bored chemist]

And here's the more interesting one.

slit expte 2 resized.jpg (44.04 kB . 775x302 - viewed 3781 times)


As you can see it curves, but it's essentially the same.

[Bored chemist]

This is the comparable image using a diffraction grating (rather than a single slit) at an angle to the beam.
Again, it's curved as expected.

slit expte 4 resized.jpg (37.13 kB . 760x225 - viewed 5894 times).