Naked Science Forum
On the Lighter Side => Science Experiments => Topic started by: hamdani yusuf on 29/03/2016 07:32:37
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In this topic I'd like to share my investigation on diffraction of light. In the first video I talk about definition and misconceptions that are often made.
I'd like to hear your opinion on this issue.
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Let me summarize my experiments in investigating diffraction of light.
Video #1 : Definition and misconceptions. Here I talk about sources of confusions we often find when discussing diffraction of light. The experiment shows the simplest case of light diffraction, which is diffraction by single edge obstruction. Basically diffraction is a name given to the phenomenon where light (or electromagnetic wave in general) can reach region behind an obstacle. It can occur when the edge of the obstacle intersect with the light beam.
Video #2 : Edge shapes effect. It shows various diffraction patterns produced by different shapes of obstacles. Here we use sharp and blunt edges, which are considered as cylindrical, and spherical obstacle.
Video #3 : Diffraction by transparent objects. It shows that transparent objects like plastic sheet can also produce diffraction. Even when the obstacle has a very similar refractive index compared to the medium, which makes it almost invisible. Here I used borosilicate glass that is immersed in sunflower oil.
Video #4 : Non-diffractive Obstacle. It shows a case where the edge of an obstacle can block a light beam without producing diffraction pattern. Here the interface between the glass and the air acts as total internal reflector which prevent the light from reaching the area behind the reflector.
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The next videos demonstrate the effect of diffraction by obstacles with more than 1 edges.
Video #5 : Double edged Obstacle. It shows the effect of diffraction produced by obstacles with 2 edges exposed to the light beam. This can be divided into 2 types : outer and inner obstacle. Outer type trims the light beam from the outer sides, and usually referred as single slit diffraction. The inner type is often called thin wire diffraction. They produce similar pattern of light and dark bands as a result of constructive and destructive interference of light from the edges.
Video #6 : Triple edged Obstacle. It shows the effect of diffraction and interference produced by adding one more edge to the obstacle. It's interesting that this experiment is never even mentioned in mainstream physics text books.
Video #7 : Quadruple edged Obstacle. The famous double slit interference is basically an outer type of quadruple edged obstacle. Its complementary inner type is the double wire obstacle, but this is very rarely discussed in physics class room.
Video #8 : Multiple edged Obstacle. Here more edges are added to the obstacles. It also shows experiment using diffraction gratings which most of us are familiar with.
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In the next videos, I show the diffraction pattern where the light source comes from various angle.
Video #9 : Horizontally tilted aperture. Here we show the effect of tilting the diffraction aperture horizontally. There is also a case of single slit diffraction with large horizontally tilted angle where the gap is actually very large compared to the wavelength. Nevertheless we can still see interference pattern.
Video #10: This video shows the effect of vertically tilting the obstacle on a light beam. The pattern seems to follow a specular reflection by cylindrical objects, which is unexplainable using Huygens’s principle.
Video #11: Diffraction of non-parallel Light Source. It's repeating experiments on diffraction of light, but now using non-parallel light source by passing the laser beam through lenses.
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Finally the last videos of this series.
Video #12: Non-diffractive Interference. There are some other optical phenomena which create interference pattern but don’t actually involve diffraction. Some sources use the term diffraction to mention some of these interference cases as if those terms are interchangeable. The video lists them up to make distinction between diffraction and interference of light clearer.
Video #13: Non-diffractive slit. Here we put Huygen’s principle as currently accepted explanation for single slit diffraction to the test. To determine whether the space or the edges of the slit as the real interfering point sources, we can conduct an experiment using a slit whose edges are not diffractive. If Huygen’s principle is correct, then we should still get interference pattern even though the edges of the slit doesn’t diffract light.
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First video is excellent! Looking forward to the rest!
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Here is Youtube complete playlist of these experiments.
/playlist?list=PLZ2PyRUoub7hmjVJT1gs03DzoVW32kLn7
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The rest of the video can be watched here
video #2 Edge shapes effect
video #3 Diffraction by transparent objects
video #4 Non-diffractive Obstacle
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video #5 Double edged Obstacle
video #6 Triple edged Obstacle
video #7 Quadruple edged Obstacle
video #8 Multiple edged Obstacle.
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video #9 Horizontally tilted diffraction
video #10 Vertically tilted diffraction
video #11 Non-parallel light source
video #12 Non-diffractive interference
video #13 Non-diffractive slit
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Does someone have access to Vantablack? Its usage is currently restricted for public use.
I'd like to see if single edge diffraction can still occur when the obstacle absorb more than 99.9% of the light hitting its surface.
I also want to see double edge diffraction, or widely known as single slit diffraction with aperture covered by Vantablack.
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I've added a new video regarding non-diffractive object whose shape resembles normal objects, unlike the one shown in video#4. The similarity is that both use total internal reflection.
youtube.com/watch?v=NULSN3OZAlQ
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After a long break, I finally finish a new video demonstrating that geometrical optics is still working in the formation of diffraction patterns.
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Im a second year high school and I need a science investigatory project about making something out of something. Like recycling something to make something that can be of use in the environment. I need it now. As in this time. Please........... Thanks.
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In the video on vertically tilted diffraction, the clip is unexpectedly cut when showing the pattern from optic fiber. Here is the raw take of the experiment.
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Here's my newest video investigating diffraction of light by producing single side interference pattern.
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Here's one of the most helpful pictures to understand the phenomenon of diffraction and interference of light.
(https://upload.wikimedia.org/wikipedia/commons/thumb/c/c2/Single_slit_and_double_slit2.jpg/525px-Single_slit_and_double_slit2.jpg)
Same double-slit assembly (0.7 mm between slits); in top image, one slit is closed. In the single-slit image, a diffraction pattern (the faint spots on either side of the main band) forms due to the nonzero width of the slit. This diffraction pattern is also seen in the double-slit image, but with many smaller interference fringes.
In this case, the slits are narrower than the opaque matter between them.
In my next video, I'll show the result of double wire experiment, which is the equivalent of double slit experiment, according to Babinet's principle.
We'll see the pattern produced by thin wires with narrow and wide gap between them. The pictures above are similar to the pattern produced by single thin wire, and double wire with wide gap, respectively.
We'll also see pattern produced by thick wires (I actually used needles) with narrow gap between them. The result turns out to be similar to the bottom picture above. But if one needle is removed, what we get is a pattern of narrow fringes where the central bright is twice as wide as the others.
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I once made a diffraction grating using wires (separated by the threads of two bolts)
It didn't work properly until I painted it black.
The reflections from the curved surfaces of the wires made the diffraction pattern more complicated.
You may encounter similar issues with needles.
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I once made a diffraction grating using wires (separated by the threads of two bolts)
It didn't work properly until I painted it black.
The reflections from the curved surfaces of the wires made the diffraction pattern more complicated.
You may encounter similar issues with needles.
Here are my results of double wire diffraction experiment. The first picture is the direct laser spot when allowed to hit the wall without obstruction. Due to lens imperfection, some artefact is visible on the wall. To avoid complication, the laser is oriented so that the spots are aligned vertically, which is on the same axis as the obstructing needles that will be used.
(https://www.thenakedscientists.com/forum/index.php?action=dlattach;topic=66301.0;attach=32400)
Below is the pattern produced by single needle.
(https://www.thenakedscientists.com/forum/index.php?action=dlattach;topic=66301.0;attach=32402)
And the pattern produced by double needle.
(https://www.thenakedscientists.com/forum/index.php?action=dlattach;topic=66301.0;attach=32404)
Notice the width of the central bright fringe, compared to other fringes. In single needle, its approximately twice as wide. Whereas in double needle, it has the same width. It's similar to single slit and double slit experiment, respectively. Moreover, the double needle creates more prominent dark fringes compared to single needle.
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Finally finished the video demonstrating single and double thin wire diffraction-interference experiment.
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And here's another experiment related to the previous one. This time we use double needle.
It demonstrates the result of double thick wire experiment, or double needle experiment, which produce diffraction-interference pattern like standard double slit experiment, if the gap between the needles are narrow.
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In the last video, are you looking at the proper part of the diffraction pattern? There should be a broad diffraction pattern from the wires as shown in your previous videos. The bright red spot at the center shows a good diffraction pattern as expected but there is a possibility that it could be caused by some irregularity in the laser itself. The diffraction pattern beyond the bright red dot should be easily visible at a much shorter distance from the laser source.
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The first picture is the direct laser spot when allowed to hit the wall without obstruction. Due to lens imperfection, some artefact is visible on the wall. To avoid complication, the laser is oriented so that the spots are aligned vertically, which is on the same axis as the obstructing needles that will be used.
You can improve the quality of the laser beam which will solve that problem.
https://www.edmundoptics.co.uk/knowledge-center/application-notes/lasers/understanding-spatial-filters/
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In the last video, are you looking at the proper part of the diffraction pattern? There should be a broad diffraction pattern from the wires as shown in your previous videos. The bright red spot at the center shows a good diffraction pattern as expected but there is a possibility that it could be caused by some irregularity in the laser itself. The diffraction pattern beyond the bright red dot should be easily visible at a much shorter distance from the laser source.
Most online formulas describing double slit experiment only consider the distance between the center of the slits, while omitting the width of the slits. The cross sectional shapes of the slits/wires are mostly ignored. So, those are precisely what we need to investigate further.
What do you expect to see if I use a better laser pointer?
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Most online formulas describing double slit experiment only consider the distance between the center of the slits, while omitting the width of the slits. The cross sectional shapes of the slits/wires are mostly ignored. So, those are precisely what we need to investigate further.
What do you expect to see if I use a better laser pointer?
My poor quality laser shows a “bull’s eye” interference pattern due to what must be some internal interference even when there is nothing in the path to produce an interference. That is why I prefer to examine the parts of interference pattern that extend beyond the bright dot in the very center.
That is also why I suggest placing the screen closer to the laser so the entire diffraction pattern is visible and not just the center. You did that in the earlier videos but not in the one with the wires and long hallway.
A poor quality laser works well enough for masked experiments such as single or double slits, but for wide open experiments with wires, you can’t be certain where the interference is coming from by looking at the bright spot in the center. However it did work nicely with the nails. That may be because they are larger and block more of the stray light.
I don’t have a good quality laser for comparison.
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I've also done the experiment of double needles in series, and repeat the single needle experiment with various distance from the wall. I got an unexpected result.
I have several laser pointers with different price tags. I think I'll try to use them for comparison.
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I don’t have a good quality laser for comparison.
You can improve the quality of the laser beam which will solve that problem.
https://www.edmundoptics.co.uk/knowledge-center/application-notes/lasers/understanding-spatial-filters/
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I just got an even stronger evidence that diffracted light is produced by the edges of the obstacle, instead of the space between those edges. The experiment involves linear polarization. So I think I'll just share some of the best explanation I can find on Youtube so we can start from the same page.
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Linear polarization is easier to understand using microwave frequency since the physical shape of the polarizer can be observed using naked eye.
I’ve been teaching microwave polarisation wrong! - A Level Physics
So it turns out the way I've been teaching microwave polarisation is wrong!! Well, it's not so much wrong, it's the fact that the 'picket fence' analogy for polarisation isn't what it first seems. Where the picket fence only allows vertically polarised light through, a corresponding polarising filter only allows horizontally polarised light through! Watch this video for more explanation.
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There will be some variations of my experiment, but here's the main scenario. A laser pointer is used as the light source to provide monochromatic coherent light. In front of it is a linear polarizer oriented diagonally 45° to the right from vertical axis. The light beam then hit a single slit aperture made of a pair of linear polarizers, where the "conductors" are oriented vertically. The light beam is then projected to a wall, where a single slit diffraction-interference pattern can be seen.
Another linear polarizer is then inserted between the single slit aperture and the wall. When it's oriented vertically, only the central point is bright, while the fringes disappear. On the other hand, when it's oriented perpendicular to the first polarizer, the center spot gets much dimmer, while the fringes are still visible, although its intensity is also reduced.
These results will have profound impact on our understanding of diffraction and interference of light. This will be the first step to explain a kind of physical phenomenon which has baffled most people like double slit experiment. Some said it's mind boggling and defies logic, some others even said that it shows that reality doesn't exist.
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These results will have profound impact on our understanding of diffraction and interference of light.
I don't think so.
This will be the first step to explain a kind of physical phenomenon which has baffled most people like double slit experiment.
I don't think the most people are baffled by the double slit experiment.
Some said it's mind boggling and defies logic, some others even said that it shows that reality doesn't exist.
I think those might just be the crazy people.
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I don't think the most people are baffled by the double slit experiment.
OK. most people just ignore it.
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I think those might just be the crazy people.
Here they are.
https://plus.maths.org/content/physics-minute-double-slit-experiment-0
One of the most famous experiments in physics is the double slit experiment. It demonstrates, with unparalleled strangeness, that little particles of matter have something of a wave about them, and suggests that the very act of observing a particle has a dramatic effect on its behaviour.
Most discussions of double-slit experiments with particles refer to Feynman's quote in his lectures: “We choose to examine a phenomenon which is impossible, absolutely impossible, to explain in any classical way, and which has in it the heart of quantum mechanics.
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And here are common explanation for single slit experiment.
All of those explanations would need to be revised.
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There will be some variations of my experiment, but here's the main scenario. A laser pointer is used as the light source to provide monochromatic coherent light. In front of it is a linear polarizer oriented diagonally 45° to the right from vertical axis. The light beam then hit a single slit aperture made of a pair of linear polarizers, where the "conductors" are oriented vertically. The light beam is then projected to a wall, where a single slit diffraction-interference pattern can be seen.
Another linear polarizer is then inserted between the single slit aperture and the wall. When it's oriented vertically, only the central point is bright, while the fringes disappear. On the other hand, when it's oriented perpendicular to the first polarizer, the center spot gets much dimmer, while the fringes are still visible, although its intensity is also reduced.
Just in case someone who already read my description above hasn't understand its implications.
- Incoming light to the single slit aperture is diagonally polarized.
- The conductors in the polarizer is vertically aligned.
- The light goes through the slit unobstructed is diagonally polarized, just like incoming light.
- The light hitting the polarizing single slit aperture causes its electric charges to vibrate vertically.
- The vibration produces electromagnetic waves which are vertically polarized, and spread horizontally creating a horizontal bright line on the screen behind the aperture. This wave spreading is what we commonly call diffraction.
- When another polarizer is placed behind the single slit aperture, with its conductors aligned vertically, vertically polarized light going through it is blocked. It leaves the screen with a central bright spot with no visible bright horizontal line commonly associated with a single slit experiment.
- It shows beyond reasonable doubt that the diffracted light must come from the material of the aperture, instead of the space between them.
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All of those explanations would need to be revised.
Here are some other explanations I find online.
https://en.wikipedia.org/wiki/Diffraction#Single-slit_diffraction
A long slit of infinitesimal width which is illuminated by light diffracts the light into a series of circular waves and the wavefront which emerges from the slit is a cylindrical wave of uniform intensity, in accordance with Huygens–Fresnel principle.
An illuminated slit that is wider than a wavelength produces interference effects in the space downstream of the slit. Assuming that the slit behaves as though it has a large number of point sources spaced evenly across the width of the slit interference effects can be calculated. The analysis of this system is simplified if we consider light of a single wavelength. If the incident light is coherent, these sources all have the same phase. Light incident at a given point in the space downstream of the slit is made up of contributions from each of these point sources and if the relative phases of these contributions vary by 2π or more, we may expect to find minima and maxima in the diffracted light. Such phase differences are caused by differences in the path lengths over which contributing rays reach the point from the slit.
We can find the angle at which a first minimum is obtained in the diffracted light by the following reasoning. The light from a source located at the top edge of the slit interferes destructively with a source located at the middle of the slit, when the path difference between them is equal to λ/2. Similarly, the source just below the top of the slit will interfere destructively with the source located just below the middle of the slit at the same angle. We can continue this reasoning along the entire height of the slit to conclude that the condition for destructive interference for the entire slit is the same as the condition for destructive interference between two narrow slits a distance apart that is half the width of the slit.
(https://upload.wikimedia.org/wikipedia/commons/thumb/3/3c/Wave_Diffraction_4Lambda_Slit.png/330px-Wave_Diffraction_4Lambda_Slit.png)
(https://upload.wikimedia.org/wikipedia/commons/thumb/7/7f/Single_Slit_Diffraction_%28english%29.svg/330px-Single_Slit_Diffraction_%28english%29.svg.png)
https://en.wikipedia.org/wiki/Diffraction_from_slits#General_diffraction
Because diffraction is the result of addition of all waves (of given wavelength) along all unobstructed paths, the usual procedure is to consider the contribution of an infinitesimally small neighborhood around a certain path (this contribution is usually called a wavelet) and then integrate over all paths (= add all wavelets) from the source to the detector (or given point on a screen).
Thus in order to determine the pattern produced by diffraction, the phase and the amplitude of each of the wavelets is calculated. That is, at each point in space we must determine the distance to each of the simple sources on the incoming wavefront. If the distance to each of the simple sources differs by an integer number of wavelengths, all the wavelets will be in phase, resulting in constructive interference. If the distance to each source is an integer plus one half of a wavelength, there will be complete destructive interference. Usually, it is sufficient to determine these minima and maxima to explain the observed diffraction effects.
The simplest descriptions of diffraction are those in which the situation can be reduced to a two-dimensional problem. For water waves, this is already the case, as water waves propagate only on the surface of the water. For light, we can often neglect one dimension if the diffracting object extends in that direction over a distance far greater than the wavelength. In the case of light shining through small circular holes we will have to take into account the full three-dimensional nature of the problem.
Several qualitative observations can be made of diffraction in general:
The angular spacing of the features in the diffraction pattern is inversely proportional to the dimensions of the object causing the diffraction. In other words: the smaller the diffracting object, the wider the resulting diffraction pattern, and vice versa. (More precisely, this is true of the sines of the angles.)
The diffraction angles are invariant under scaling; that is, they depend only on the ratio of the wavelength to the size of the diffracting object.
When the diffracting object has a periodic structure, for example in a diffraction grating, the features generally become sharper. The fourth figure, for example, shows a comparison of a double-slit pattern with a pattern formed by five slits, both sets of slits having the same spacing between the center of one slit and the next.
https://en.wikipedia.org/wiki/Diffraction_from_slits#Single_slit
(https://upload.wikimedia.org/wikipedia/commons/e/e4/Wavelength%3Dslitwidthblue3D.gif)
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Here's another example from hyperphysics.
http://hyperphysics.phy-astr.gsu.edu/hbase/phyopt/sinslit.html
(https://www.thenakedscientists.com/forum/proxy.php?request=http%3A%2F%2Fhyperphysics.phy-astr.gsu.edu%2Fhbase%2Fphyopt%2Fimgpho%2Fsinslit.png&hash=7e06bef69c7494d0722f4fbf50a18a84)
The diffraction pattern at the right is taken with a helium-neon laser and a narrow single slit. The use of the laser makes it easy to meet the requirements of Fraunhofer diffraction. With a general light source, it is possible to meet the Fraunhofer requirements with the use of a pair of lenses.
http://hyperphysics.phy-astr.gsu.edu/hbase/phyopt/sinint.html#c1
(https://www.thenakedscientists.com/forum/proxy.php?request=http%3A%2F%2Fhyperphysics.phy-astr.gsu.edu%2Fhbase%2Fphyopt%2Fimgpho%2Fsinint6.png&hash=d72a95816d8d5200e4f3952765ee2a64)
Under the Fraunhofer conditions, the wave arrives at the single slit as a plane wave. Divided into segments, each of which can be regarded as a point source, the amplitudes of the segments will have a constant phase displacement from each other, and will form segments of a circular arc when added as vectors. In this way, the single slit intensity can be constructed.
(https://www.thenakedscientists.com/forum/proxy.php?request=http%3A%2F%2Fhyperphysics.phy-astr.gsu.edu%2Fhbase%2Fphyopt%2Fimgpho%2Fsinint7.png&hash=65a80b42a82dbcc7b38a238773e1bc33)
(https://www.thenakedscientists.com/forum/proxy.php?request=http%3A%2F%2Fhyperphysics.phy-astr.gsu.edu%2Fhbase%2Fphyopt%2Fimgpho%2Fsinint8.png&hash=0cc2148fa2ae9fc246ec013ce2acbfab)
The diagrams above show that intensity of the fringes doesn't take the material characteristics of the aperture into account.
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Here's another source, which shows more similar explanation to what's often found in high school textbooks.
https://phys.libretexts.org/Bookshelves/University_Physics/Book%3A_University_Physics_(OpenStax)/University_Physics_III_-_Optics_and_Modern_Physics_(OpenStax)/04%3A_Diffraction/4.02%3A_Single-Slit_Diffraction
(https://phys.libretexts.org/@api/deki/files/17000/Figure4-4.png?revision=1)
Figure 4.2.3 : Light passing through a single slit is diffracted in all directions and may interfere constructively or destructively, depending on the angle. The difference in path length for rays from either side of the slit is seen to be a sinθ .
Here, the light arrives at the slit, illuminating it uniformly and is in phase across its width. We then consider light propagating onwards from different parts of the same slit. According to Huygens’s principle, every part of the wave front in the slit emits wavelets, as we discussed in The Nature of Light. These are like rays that start out in phase and head in all directions. (Each ray is perpendicular to the wave front of a wavelet.) Assuming the screen is very far away compared with the size of the slit, rays heading toward a common destination are nearly parallel. When they travel straight ahead, as in part (a) of the figure, they remain in phase, and we observe a central maximum. However, when rays travel at an angle θ relative to the original direction of the beam, each ray travels a different distance to a common location, and they can arrive in or out of phase. In part (b), the ray from the bottom travels a distance of one wavelength λ farther than the ray from the top. Thus, a ray from the center travels a distance λ/2 less than the one at the bottom edge of the slit, arrives out of phase, and interferes destructively. A ray from slightly above the center and one from slightly above the bottom also cancel one another. In fact, each ray from the slit interferes destructively with another ray. In other words, a pair-wise cancellation of all rays results in a dark minimum in intensity at this angle. By symmetry, another minimum occurs at the same angle to the right of the incident direction (toward the bottom of the figure) of the light.
At the larger angle shown in part (c), the path lengths differ by 3λ/2 for rays from the top and bottom of the slit. One ray travels a distance λ different from the ray from the bottom and arrives in phase, interfering constructively. Two rays, each from slightly above those two, also add constructively. Most rays from the slit have another ray to interfere with constructively, and a maximum in intensity occurs at this angle. However, not all rays interfere constructively for this situation, so the maximum is not as intense as the central maximum. Finally, in part (d), the angle shown is large enough to produce a second minimum. As seen in the figure, the difference in path length for rays from either side of the slit is asinθ , and we see that a destructive minimum is obtained when this distance is an integral multiple of the wavelength.
Thus, to obtain destructive interference for a single slit,
a sinθ=mλ
where
m=±1,±2,±3,... ,
a is the slit width,
λ is the light’s wavelength,
θ is the angle relative to the original direction of the light, and
m is the order of the minimum.
(https://phys.libretexts.org/@api/deki/files/17001/Figure4-5.png?revision=1)
Figure 4.2.3 : A graph of single-slit diffraction intensity showing the central maximum to be wider and much more intense than those to the sides. In fact, the central maximum is six times higher than shown here.
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Most explanations about diffraction of light depict the edges of the slit as featureless rectangular solid objects, which perfectly absorb the light hitting them, while letting the light missing them passes through. The authors seem to assume that the effects of the edges are insignificant in shaping the pattern of diffracted light. My experiments will be reminders that false assumptions can lead to unexpected results.
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Here they are.
Why do you think those people are crazy? I didn't see where any of them said "reality doesn't exist".
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Here they are.
Why do you think those people are crazy? I didn't see where any of them said "reality doesn't exist".
I didn't call them crazy. You did.
These results will have profound impact on our understanding of diffraction and interference of light.
I don't think so.
This will be the first step to explain a kind of physical phenomenon which has baffled most people like double slit experiment.
I don't think the most people are baffled by the double slit experiment.
Some said it's mind boggling and defies logic, some others even said that it shows that reality doesn't exist.
I think those might just be the crazy people.
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Questions about reality.
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I didn't call them crazy. You did
This isn't that difficult. You said some people think that the double slit experiment shows that reality doesn't exist. I said those people are crazy people. Then you quoted some individuals talking about the double slit experiment and implied I think they are crazy. If these people you quoted believe that reality exists then I don't think they're crazy.
This thread is getting as pointless as your thread about heat transfer between ice and water.
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Questions about reality.
Oh great here we go, hamdani is hijacking his own thread again.
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Most explanations about diffraction of light depict the edges of the slit as featureless rectangular solid objects, which perfectly absorb the light hitting them, while letting the light missing them passes through. The authors seem to assume that the effects of the edges are insignificant in shaping the pattern of diffracted light. My experiments will be reminders that false assumptions can lead to unexpected results.
My last experiment with polarized diffraction is not an isolated anomalous result. It's a corroborating evidence with my previous experiments, especially diffraction in microwave transceiver, non-diffractive edges with total internal reflection, and vertically tilted diffraction.
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I didn't call them crazy. You did
This isn't that difficult. You said some people think that the double slit experiment shows that reality doesn't exist. I said those people are crazy people. Then you quoted some individuals talking about the double slit experiment and implied I think they are crazy. If these people you quoted believe that reality exists then I don't think they're crazy.
This thread is getting as pointless as your thread about heat transfer between ice and water.
This is what you should have done to avoid misunderstandings. Quote only the sentence you are going to comment. Here's an example.
some others even said that it shows that reality doesn't exist.
Or you can mark the portion of your concern, like using italic or bold font.
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Questions about reality.
Oh great here we go, hamdani is hijacking his own thread again.
Those videos were meant to answer your question. It's fine if you already forget it.
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This thread is getting as pointless as your thread about heat transfer between ice and water.
What makes you think that they are pointless?
Perhaps you haven't understand them yet?
Or may be you think that they don't affect your personal life at all?
I realize that scientific research is not everyone's passion, although most people have some degrees of curiosity.
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My last experiment with polarized diffraction is not an isolated anomalous result. It's a corroborating evidence with my previous experiments, especially diffraction in microwave transceiver, non-diffractive edges with total internal reflection, and vertically tilted diffraction.
This video showing a half interference pattern is also a strong evidence corroborating with other experiments above.
Here's my newest video investigating diffraction of light by producing single side interference pattern.
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Here's another video trying to explain the double slit experiment.
Down The Rabbit Hole of the Double Slit Experiment | Answers With Joe
The Double Slit Experiment started as a way to determine if light is a wave or a particle - but it uncovered mysteries that have baffled science to this day.
In the late 1600’s it was pretty much settled science that light traveled as a particle.
There had been many experiments that seemed to back this up and it even had the support of Sir Isaac Newton.
But then a physicist named Thomas Young created the double-slit experiment. The thinking was, if light were traveling as a particle, it would create 2 parallel lines on the background, because the particles that are passing through the two slits would hit the wall behind those two slits.
Instead, he got an interference pattern. This can only happen if the light was traveling as a wave. But other experiments proved light was a particle. Somehow light functioned both as a particle and as a wave.
This was known as the wave-particle duality.
in the 1920's, physicists added another layer to the experiment when they fired photons through one at a time, amazingly still getting the interference pattern.
This proved that the photons were going through both slits at the same time and interfering with themselves.
This is because quantum particles travel in a wave function of potentials, only returning to the particle state when the wave function collapses.
Adding to the weirdness was another extension of the Double Slit Experiment - the Which Way variation.
In this experiment, they placed a tiny detector on one of the slits. Surprisingly, the pattern on the back wall of the experiment was a particle pattern. This means the wave function collapsed before it went through the slits. Why? Because it was being observed.
It was the act of observing the particle that caused its wave form to collapse. This cannot be explained to this day.
Yet another layer of weirdness is the Delayed Choice experiment conducted by John Archibald Wheeler.
In this, he added a second double slit that changes while the photon is in mid-flight. The results showed that by changing the nature of the second slit, it altered the behavior of the particle at the first slit.
In other words, this particle was being altered by things that hadn’t happened yet. Future events can change the present.
When Thomas Young created the double slit experiment, he had no idea the endless stream of mysteries this would create. Who knows what mysteries still await us...
In the past, if some axioms lead to ridiculous conclusion, we would reject them, or modify some of them. But identifying those false assumptions could be tricky, especially when they are hidden, and we are not aware of making them in the first place, like the featureless and infinitely rigid blocks of single or double slit aperture.
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Frequently. I am a physicist.
It looks like we are lucky to have a physicist on board. I'd like to hear what you think about this problem.
Or may be you know someone who is more suitable to give an answer.
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In the past, if some axioms lead to ridiculous conclusion, we would reject them, or modify some of them. But identifying those false assumptions could be tricky, especially when they are hidden, and we are not aware of making them in the first place, like the featureless and infinitely rigid blocks of single or double slit aperture.
Some modern scientists seem to be too confident in their own scientific knowledge. So when their predictions differ from observations, they just declare that objective reality may not exist, instead of scrutinizing their assumptions more thoroughly.
https://www.popularmechanics.com/science/a40460495/objective-reality-may-not-exist/
...
That reality might be in the eye of the observer is a very peculiar aspect of the physical reality in the quantum domain, and the mystery itself shows no signs of abating, both researchers agree.
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Investigation on Diffraction of Light 20: Revisiting Vertically Tilted Diffraction, fixing glitches in previously uploaded video.
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Some modern scientists seem to be too confident in their own scientific knowledge. So when their predictions differ from observations, they just declare that objective reality may not exist, instead of scrutinizing their assumptions more thoroughly.
When do you imagine that happened?
Because, in general, if you make a discovery where reality departs from theory, that's your chance to get a Nobel Prize.
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Frequently. I am a physicist.
It looks like we are lucky to have a physicist on board. I'd like to hear what you think about this problem.
Or may be you know someone who is more suitable to give an answer.
Apologies for picking this up so late in the discussion. Please remind me which problem?
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Some modern scientists seem to be too confident in their own scientific knowledge. So when their predictions differ from observations, they just declare that objective reality may not exist, instead of scrutinizing their assumptions more thoroughly.
When do you imagine that happened?
Because, in general, if you make a discovery where reality departs from theory, that's your chance to get a Nobel Prize.
Anytime someone says that double slit experiment is weird and defy logic. Just like this year's Nobel prize in physics.
https://www.popularmechanics.com/science/a40460495/objective-reality-may-not-exist/
...
That reality might be in the eye of the observer is a very peculiar aspect of the physical reality in the quantum domain, and the mystery itself shows no signs of abating, both researchers agree.
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Frequently. I am a physicist.
It looks like we are lucky to have a physicist on board. I'd like to hear what you think about this problem.
Or may be you know someone who is more suitable to give an answer.
Apologies for picking this up so late in the discussion. Please remind me which problem?
Here. See the pattern shown in 0:07. Do you have a better explanation?
Here's my newest video investigating diffraction of light by producing single side interference pattern.
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Investigation on Diffraction of Light 21 : Long Shot Diffraction
Experiment on diffraction of light with long distance between the obstacle and the screen to show the difference of interference pattern between single slit and thin wire diffraction.
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Investigation on Diffraction of Light 21 : Long Shot Diffraction
Experiment on diffraction of light with long distance between the obstacle and the screen to show the difference of interference pattern between single slit and thin wire diffraction.
Something new and interesting for me, if you still find this kind of video, please let me know.
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Investigation on Diffraction of Light 21 : Long Shot Diffraction
Experiment on diffraction of light with long distance between the obstacle and the screen to show the difference of interference pattern between single slit and thin wire diffraction.
Something new and interesting for me, if you still find this kind of video, please let me know.
I've got some other videos in progress. Most of them are investigating the behavior of electromagnetic waves in various frequency, from radio wave, microwave, and visible light. I'll share them here as soon as I finish editing and upload them to my YouTube channel.
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I just got an even stronger evidence that diffracted light is produced by the edges of the obstacle, instead of the space between those edges. The experiment involves linear polarization.
I've finally uploaded the video.
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Just in case you get confused by the polarization markings of the polarizer films, I recommend you to watch this informative video.
Linear polarization is easier to understand using microwave frequency since the physical shape of the polarizer can be observed using naked eye.
I’ve been teaching microwave polarisation wrong! - A Level Physics
So it turns out the way I've been teaching microwave polarisation is wrong!! Well, it's not so much wrong, it's the fact that the 'picket fence' analogy for polarisation isn't what it first seems. Where the picket fence only allows vertically polarised light through, a corresponding polarising filter only allows horizontally polarised light through! Watch this video for more explanation.
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I've finished editing a new video on horizontally tilted diffraction. The first part is just fixing my old clips, while the last part contains new material. I'll share it here when I finished uploading it to my Youtube channel.
Many sources say that diffraction-interference pattern in a single slit experiment require the slit to be narrow, and comparable to the wavelength of the light wave. The word comparable in this context is not well defined.
Some of them also mention that the edges of the slit must be sharp.
My experiments will show that they are not necessarily true.
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I've also finished editing a short video showing the occurrence of half interference pattern.
The laser beam seemingly only interact with a single edge of the obstructing object.
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I've finished editing a new video on horizontally tilted diffraction. The first part is just fixing my old clips, while the last part contains new material. I'll share it here when I finished uploading it to my Youtube channel.
Many sources say that diffraction-interference pattern in a single slit experiment require the slit to be narrow, and comparable to the wavelength of the light wave. The word comparable in this context is not well defined.
Some of them also mention that the edges of the slit must be sharp.
My experiments will show that they are not necessarily true.
Here you are.
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I've also finished editing a short video showing the occurrence of half interference pattern.
The laser beam seemingly only interact with a single edge of the obstructing object.
It's a bit surprising.
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It's a bit surprising.
To whom?
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It's a bit surprising.
To whom?
To me.
My previous experiments of single edge diffraction using various materials didn't show any interference pattern. They include glass, acrylic, plastics, wood, paper, graphite, rubber, aluminum, carbon steel, stainless steel, copper, and some others.
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Here's another video about the real experiment by another Youtuber, not just some animations which don't represent physical reality.
The Real Double Slit Experiment.
This video was edited 30-12-2022. I removed everything but the experimental parts of the original video. The reason for this is that I was no longer behind the way I explained the experiments, especially the quantum aspects. What I will do i upload the original video for reference as unlisted and place the reference to it here.
In the video I show you how you can use a microscope to visualize theEM- wave propagation after light has passed the slits.
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My previous experiments of single edge diffraction using various materials didn't show any interference pattern. They include glass, acrylic, plastics, wood, paper, graphite, rubber, aluminum, carbon steel, stainless steel, copper, and some others.
Was the rest of the experimental setup identical?
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My previous experiments of single edge diffraction using various materials didn't show any interference pattern. They include glass, acrylic, plastics, wood, paper, graphite, rubber, aluminum, carbon steel, stainless steel, copper, and some others.
Was the rest of the experimental setup identical?
Some of them were, but some were not. The shapes of their edges were arbitrary, depending on the objects that I could randomly find. But they can be classified into two general category : those with sharp edge and those with blunt edge, just like my experiments with the galvanized bent plate.
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My previous experiments of single edge diffraction using various materials didn't show any interference pattern. They include glass, acrylic, plastics, wood, paper, graphite, rubber, aluminum, carbon steel, stainless steel, copper, and some others.
Was the rest of the experimental setup identical?
Some of them were, but some were not. The shapes of their edges were arbitrary, depending on the objects that I could randomly find. But they can be classified into two general category : those with sharp edge and those with blunt edge, just like my experiments with the galvanized bent plate.
So, you did different things, and got different results.
You think this is surprising.
Do you understand why we don't think this is surprising?
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Do you understand why we don't think this is surprising?
Perhaps because you haven't done those various experiments yourself.
Perhaps you don't have adequate knowledge about diffraction of light which allows you to make a testable prediction.
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So, you did different things, and got different results.
You think this is surprising.
It seems that you misunderstood my simple sentence.
Some of them were,
It means that my previous experiments with the same setups as this one (the only difference is the material of the obstacle), shown no interference pattern in the shadow region of the obstacle.
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I've finished editing another short video investigating diffraction of light. It started with the setup from horizontally tilted diffraction, where two knifves forming a single slit aperture are separated away from each other. One knife is further away from the light source.
In the new video, the far knife is flipped, so it obstructs the light beam from the same side as the near knife.
The next experiment replaces the knives with the folded galvanized plate used in previous video. You'll see what happens.
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It means that my previous experiments with the same setups as this one (the only difference is the material of the obstacle), shown no interference pattern in the shadow region of the obstacle.
How carefully did you look?
How big and how bright would you expect the pattern to be?
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It means that my previous experiments with the same setups as this one (the only difference is the material of the obstacle), shown no interference pattern in the shadow region of the obstacle.
How carefully did you look?
How big and how bright would you expect the pattern to be?
To make sure, I've rechecked the result for some materials in single edge diffraction experiment. It turned out that some of them also show some interference pattern on the shadow region, although the contrast is not that clear, which made me unsure if it's just an artefact from the laser pointer. Furthermore, the size of the pattern is so small that it's only visible if the distance of the screen is long enough. Although the pattern can be seen by naked eye, my camera can't capture it clearly.
Nevertheless, the interference pattern on the shadow region produced by galvanized steel plate is much obvious, as shown in my experiment of diffraction interference effect by obstacles on the same side.
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At 1: 27 you say it's not clear if you have a pattern.
I think you need a better experimental setup.
Do you have a spatial filter?
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At 1: 27 you say it's not clear if you have a pattern.
I think you need a better experimental setup.
Do you have a spatial filter?
You can see in the video, there are some spots slightly darker than the average. But they don't seem to appear at regular interval.
No, I don't have any.
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Someone else also tried to demonstrate diffraction and interference effect of two edges on the same side.
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I'm preparing for double wires experiment, but this time the wires have different sizes. I think it's much easier to do than double slits type. They should produce similar results, according to Babinet's principle.
Previous experiment shows that wrinkles on the wires affect the diffraction interference pattern. That's why I ordered needles commonly used to clean up 3D printer nozzles.
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The diffraction pattern of light reflected from a cylinder is different to that from light going past an edge.
You might want to paint the wires black.
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The diffraction pattern of light reflected from a cylinder is different to that from light going past an edge.
You might want to paint the wires black.
Many DIY single slit experiments I found in YouTube use knife edges made of bare metal.
I've also tried various kind of paints on metal cylinders in my earliest attempt to conduct experiments in diffraction of light, from carbon black to silver, even transparent and fluorescent types. I found no significant difference. I still have the raw footages, but I didn't make the video since I didn't think it was interesting.
I haven't tried some new technology like Vantablack, though. But considering how it works, I don't think it would make much difference. Remember that a borosilicate glass submerged in sunflower oil still produce diffraction pattern, even though they have very similar refractive index which makes it almost invisible.
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I haven't tried some new technology like Vantablack, though. But considering how it works, I don't think it would make much difference. Remember that a borosilicate glass submerged in sunflower oil still produce diffraction pattern, even though they have very similar refractive index which makes it almost invisible.
I forgot about the peculiar result in diffraction pattern produced by a single edge made of galvanized steel. It seems like we get interference of light from the core metal and from the coating layer. So I can't predict one way or another until I do the experiment in real life using Vanta black or its equivalent.
I'm curious why there's no mention to musou black in Wikipedia while there are some videos about it in YouTube.
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Here's a demonstration of multiple slit diffraction-interference experiment of light.
And here's the picture from an online source.
(https://study.com/cimages/videopreview/multiple-slit-diffraction-interfnce-pattern-equations-thumbnail_136763.jpg)
The slits presumably have the same size, and they are separated by the same distances.
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I got bored during lockdown so I decided to measure the wavelength of some light- the green beam from a laser.
It's not that I had any real doubt about it being 532 nm, but I wondered how I could check.
So I looked into thee history of the diffraction grating and discovered this.
https://en.wikipedia.org/wiki/Diffraction_grating#:~:text=The%20first%20man%2Dmade%20diffraction,wire%20diffraction%20grating%20in%201821.
"The first man-made diffraction grating was made around 1785 by Philadelphia inventor David Rittenhouse, who strung hairs between two finely threaded screws"
Fraunhofer did something similar with wires.
I had a go at copying it- after all, I have access to machine-cut screws of pretty good accuracy- and I can check the pitch easily enough.
So I made a grating with a 0.4mm pitch screw and some about 0.2mm coper wire.
Took a while, and it's fiddly as hell.
And it was lousy.
The diffraction pattern was all wrong.
Until I painted it black.
In retrospect I might have done better with black sewing thread.
Later on, I realised I could do better with a grating printed out on an inkjet printer onto OHP slide material.
There's software here.
https://www.coaa.co.uk/software_astronomy.htm
But it was clear that the reflections from the surfaces of the wires really messed up the pattern.
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I haven't tried some new technology like Vantablack, though. But considering how it works, I don't think it would make much difference. Remember that a borosilicate glass submerged in sunflower oil still produce diffraction pattern, even though they have very similar refractive index which makes it almost invisible.
I forgot about the peculiar result in diffraction pattern produced by a single edge made of galvanized steel. It seems like we get interference of light from the core metal and from the coating layer. So I can't predict one way or another until I do the experiment in real life using Vanta black or its equivalent.
I'm curious why there's no mention to musou black in Wikipedia while there are some videos about it in YouTube.
This video shows that even the darkest surface is reflective at grazing angle, which is what counts in the case of diffraction.
The World's Blackest Car Is Darker Than Musou Black!
See at 4:40
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Fraunhofer did something similar with wires.
I had a go at copying it- after all, I have access to machine-cut screws of pretty good accuracy- and I can check the pitch easily enough.
So I made a grating with a 0.4mm pitch screw and some about 0.2mm coper wire.
Took a while, and it's fiddly as hell.
And it was lousy.
The diffraction pattern was all wrong.
Until I painted it black.
In retrospect I might have done better with black sewing thread.
In my experience, thin copper wire strands tend to wrinkle, especially when they were taken from stranded cables. I think it would be visible under a microscope. I don't think that sewing threads would be much better.
(https://upload.wikimedia.org/wikipedia/commons/thumb/a/a8/Blue%2BRed_String_Under_Microscope_%2840x%29.jpg/417px-Blue%2BRed_String_Under_Microscope_%2840x%29.jpg)
The paint may had straightened out its surface.
My experiments using needles gave better results than thin wires.
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Someone else also tried to demonstrate diffraction and interference effect of two edges on the same side.
Here's the short version using knife edges.
This video shows the setup of the 2 Edge Diffraction pattern experiment. The diffraction pattern has more than 100 nodes in the pattern. It uses 2 razor blades held in binder clips and a laser pointer. The razor blades and laser pointer are about 20 feet from the paper displaying the diffraction pattern.
We may argue that the interference pattern shown on the wall is not formed by diffracted lights. They come from the light being scattered by the edge of the razor blades instead. The area on the wall where interference pattern is observed is not located behind the obstacles.
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Here's another example of double slit interference using ordinary objects.
The interference pattern indicates that the width of each slits are much smaller than the distance between them. The regularity of fringes' width indicates that the slits have equal width.
But the pattern also shows that they are not perfectly parallel.
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I've made the double wires experiment using needles of different sizes.
The first experiment used 0.2 and 0.3 mm needles, while the second experiment used 0.3 and 0.6 mm.
The diffraction-interference pattern are less regularly spaced. The brightness of the fringes are also less periodical.
It supports the hypothesis that the interfering light sources come from the edges instead of the space between them.
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I've been avoiding to post Utube vids...anywayz, here it is...
Thanks & Credits & Source -
Mithuna Yoganathan/Looking Glass Universe(channel)/YouTube.
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I've made the double wires experiment using needles of different sizes.
The first experiment used 0.2 and 0.3 mm needles, while the second experiment used 0.3 and 0.6 mm.
The diffraction-interference pattern are less regularly spaced. The brightness of the fringes are also less periodical.
It supports the hypothesis that the interfering light sources come from the edges instead of the space between them.
It's unfortunate that I haven't found enough time to spare to edit, and add narration to the video. I've got tight schedules in the workplace and personal life. But the ideas for other experiments keep coming, which means I'm having a longer backlog.
I don't know which experimental results will convince people that currently common explanation for diffraction of light is erroneous. But I think the more various results against it increases the chance that people will notice.
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Just found a video showing refraction of light in aerogel block. Unfortunately, I can't find the video showing experiments of diffraction caused by the edge of aerogel. And I can't find where to buy the aerogel blocks either. I'd like to make a single slit diffraction experiment using two blocks of aerogel.
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Here's another type of new material which I'm curious to see the results on diffraction experiments. This mirror made of dielectric material is claimed to be the most reflective mirror in the world, which reflects more than 99.5 percent of visible light.
I also want to know about its penetration depth.
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Here's another double slit experiment on YouTube showing a clear interference pattern.
Its shape implies that the slits are much narrower than the distance between them. It also implies that the slits have smooth edges, consistent widths, and parallel to each other. Those are not easy features to achieve. I took them for granted until I tried to make the experiment myself.
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Its shape implies that the slits are much narrower than the distance between them.
The pictures below show the different case.
(https://media.cheggcdn.com/media/5b1/5b15978a-7a8b-4c28-8c47-addc23f43277/phpGQmjXp.png)
(https://upload.wikimedia.org/wikipedia/commons/thumb/c/c2/Single_slit_and_double_slit2.jpg/525px-Single_slit_and_double_slit2.jpg)
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In this video, the distance between the slits seems to be more similar to the width of the slits.
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Video showing single slit diffraction of a laser as the slit width is adjusted. Suitable for A-Level Physics.
Let's focus on a single point in the center of the bright pattern on the screen. When the slit is narrow, this spot becomes much dimmer compared to when the slit is wider, even though the ray of light can still go directly from the light source to that specific spot on the screen.
It could mean that the opaque materials that the single slit apparatus is made of have blocked some of the light that initially would go to that central spot.
Or the edges of the slit have deflected the ray of light hitting them to the central spot, and produce partially destructive interference with the direct ray of light to that spot.
Or a combination of both.
Is there a way to determine which case is the most correct interpretation?
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On all of these questions you ask, have you ever gotten an answer that you accepted? My guess is no. I'll have just assume the answer is no since this thread is now on ignore.
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On all of these questions you ask, have you ever gotten an answer that you accepted? My guess is no. I'll have just assume the answer is no since this thread is now on ignore.
What's your answer to my question below?
Video showing single slit diffraction of a laser as the slit width is adjusted. Suitable for A-Level Physics.
Let's focus on a single point in the center of the bright pattern on the screen. When the slit is narrow, this spot becomes much dimmer compared to when the slit is wider, even though the ray of light can still go directly from the light source to that specific spot on the screen.
It could mean that the opaque materials that the single slit apparatus is made of have blocked some of the light that initially would go to that central spot.
Or the edges of the slit have deflected the ray of light hitting them to the central spot, and produce partially destructive interference with the direct ray of light to that spot.
Or a combination of both.
Is there a way to determine which case is the most correct interpretation?
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This simple experiment shows that light takes a definitive path during diffraction and interference.
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Professional variable slit aperture is quite expensive. This is an affordable alternative using 2 pencils.
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I've just recorded a variation of needle diffraction. In this version, the "needle" model is elongated in the direction of light propagation. It can be done using a name card, with the thickness around a half millimeter. Interestingly, the width of central bright spot in the interference pattern it produced is the same as the side spots. Instead of twice as wide like in a normal needle diffraction or single slit experiment.
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I've just recorded a variation of needle diffraction. In this version, the "needle" model is elongated in the direction of light propagation. It can be done using a name card, with the thickness around a half millimeter. Interestingly, the width of central bright spot in the interference pattern it produced is the same as the side spots. Instead of twice as wide like in a normal needle diffraction or single slit experiment.
I've also recorded its Babinet's equivalent, which is thick single slit experiment. The result is more like a normal single slit experiment, where the central bright spot is twice as wide as the side spots. I think I'll compile them in a single video to show the comparison.
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Here's the video.
Investigation on Diffraction of Light 26: Deep Single Slit and Wire
This video compares the result of diffraction and interference pattern from a deep single slit experiment and a thick single wire experiment. It explores the effects of depth or thickness of the aperture to the diffraction and interference pattern which is rarely discussed elsewhere.
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When I googled "single slit experiment", this link shows up as the first answer.
In a single slit experiment, an alternating dark and bright pattern can be seen when light is imposed on a slit with a size corresponding to the wavelength of light. The only differences between a single slit and a double-slit experiment are the diffraction patterns and the intensity graphs.
https://www.inspiritvr.com/single-slit-diffraction-study-guide/#:~:text=In%20a%20single%20slit%20experiment%2C%20an%20alternating%20dark%20and%20bright,patterns%20and%20the%20intensity%20graphs.
What is Diffraction?
The process of bending light around corners such that it spreads out and illuminates regions where a shadow is anticipated is known as diffraction of light. In general, because both occur concurrently, it is difficult to distinguish between diffraction and interference. The diffraction of light is what causes the silver line we see in the sky. A silver line appears in the sky as the sunlight penetrates or strikes the cloud.
What Is Single Slit Diffraction?
The curving of light waves around a tight turn of an obstacle or an opening is known as the diffraction of light.
The single slit diffraction?s meaning is that an alternating dark and bright pattern can be seen when light is imposed on a slit with a size corresponding to the wavelength of light.
When light strikes the gap, secondary wavelets form at each point, as per Huygens? rule.
These wavelets start out in a phased manner and then disperse on all sides.
Each one of them covers a specific path to reach any location on the screen.
Due to the path difference, they reach diverse phases and may interact either constructively or destructively.
Single Slit Diffraction Formula
(https://images.ctfassets.net/4yflszkpcwkt/3L73624wLcTMAetsiPgccs/a64af9d93748215fcc828b19dfe065bc/sinslit.png)
There are many weaknesses in the explanation above, but at least it correctly acknowledge that diffraction and interference are two distinct phenomena which often occur concurrently. There are sources which incorrectly declare that they are the same physical phenomenon, distinguished only by the number of slits involved.
Huygens? rule is commonly used to explain the diffraction-interference pattern produced by single slit experiment. It coincidentally matches with the standard setup. But more evidences are keep coming up contradicting the explanation using some variation of the experimental setup, e.g.
- Horizontally tilted diffraction.
- Vertically tilted diffraction.
- Non-diffractive slit using total internal reflection as the obstacle.
- Diffraction by polarizing obstacle.
- Diffraction by thick wire.
How many more evidence is required to convince us that we need a new explanation to replace Huygen's rule for explaining single slit experiment?
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There are many weaknesses in the explanation above,
The most obvious one that I suspected right away is from multiple slit experiment. The more numbers of slit produce thinner bright spots. When there are infinitely many slits involved like what's explained in many sources, the bright spots should be infinitely thin. But that's not what we observe.
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The most obvious one that I suspected right away is from multiple slit experiment. The more numbers of slit produce thinner bright spots. When there are infinitely many slits involved like what's explained in many sources, the bright spots should be infinitely thin. But that's not what we observe.
Really? When have observed the experiment with an infinite number of slits?
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What's your answer to my question below?
"Is there a way to determine which case is the most correct interpretation?"
Unfortunately there is no interpretation that you would accept, for some reason you never come to a conclusion, you just continue to ask the same question over and over ad nauseam.
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The most obvious one that I suspected right away is from multiple slit experiment. The more numbers of slit produce thinner bright spots. When there are infinitely many slits involved like what's explained in many sources, the bright spots should be infinitely thin. But that's not what we observe.
Really? When have observed the experiment with an infinite number of slits?
Read the analysis in https://www.thenakedscientists.com/forum/index.php?topic=66301.msg719198#msg719198
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What's your answer to my question below?
"Is there a way to determine which case is the most correct interpretation?"
Unfortunately there is no interpretation that you would accept, for some reason you never come to a conclusion, you just continue to ask the same question over and over ad nauseam.
I accept explanations that are not contradicted by experimental results. It's possible that more than one distinct explanations produce the same result for an experiment. But with more experiments some of them may start to fail.
You keep saying that they are well understood, without showing your own understanding about them.
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I'm planning to make another experiment in diffraction of light. I call it double layer single slit diffraction.
But I think I'll only do it after finishing the other experiment in progress, which uses electrohydrodynamic balance.
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If it has a finite thickness, it isn't an edge, so you need an infinite number of Huygens constructions to predict the outcome. Better to simply note that as n→∞ so the diffraction pattern becomes less intense and more diffuse than two classic single-ray plots.
If you want to have more detailed technical discussion about diffraction of light, let's do it here.
What prevents the wavelets from bending toward the left side of the boundary between reflective and transparent surface?
(https://www.thenakedscientists.com/forum/index.php?action=dlattach;topic=66301.0;attach=34264)
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I accept explanations that are not contradicted by experimental results. It's possible that more than one distinct explanations produce the same result for an experiment. But with more experiments some of them may start to fail.
Huygens? rule is commonly used to explain the diffraction-interference pattern produced by single slit experiment. It coincidentally matches with the standard setup. But more evidences are keep coming up contradicting the explanation using some variation of the experimental setup, e.g.
- Horizontally tilted diffraction.
- Vertically tilted diffraction.
- Non-diffractive slit using total internal reflection as the obstacle.
- Diffraction by polarizing obstacle.
- Diffraction by thick wire.
How many more evidence is required to convince us that we need a new explanation to replace Huygen's rule for explaining single slit experiment?
Some of you may get bored that I keep mentioning my experimental results regarding diffraction of light. I think it's necessary because some people keep forgetting about them, and go on making comments as if they don't exist.
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The use of those lenses caused the light beam to be no longer parallel. It makes position of the aperture has significant impact on the interference patterns.
At 0:20 ten pinholes can produce interference patterns similar to diffraction grating. I'm curious what we'll get with just two pin holes.