Diffraction Definition and 1000 Threads

  1. T

    Reciprocal lattice for FCC and diffraction peaks

    My issue is more with the steps to approach rather than the calculations. I was just wondering if someone could confirm my approach to be correct. As it asking for the reciprocal lattice of an FCC I assume this would mean I need to use the points on the BCC to calculate the geometrical...
  2. DPMF6973

    Index of refraction and wavelength

    The problem is multiple choice. A) refraction b) diffraction c) reflection d) dispersion An explanation would also be greatly appreciated!
  3. M

    How can I find the width of the central diffraction maximum.

    If I am given the width of the slit (b), wavelength of the light (λ), and the distance of the slit from the screen (D), how can I find the width of the central maximum (d)? My book says d/2=Dλ/b, but with no explanation and I don't understand why. Where does this formula come from? Thank you...
  4. M

    Controlling light diffraction angle with a holographic "lens"

    I'm a physics student, and working on a class project that requires coming up with a method to control the exit angle (diffraction angle) of a monochromatic light source. For example, taking a laser (monochromatic, coherent light source), spreading the beam, and directing the light at a piece...
  5. R

    B Particle properties conclusion from no-slit diffraction

    Is it possible to infer particle properties from 2 sources diffraction with no slit/slits involved? Some explanations of experiments i can find, if i understand them correctly at all, relate to the possibility of concluding particle momentum, from absorption lines, when emanating from a single...
  6. A

    I Can Quantized Momentum Transfer Explain Double-Slit Interference Patterns?

    In https://www.sciencedirect.com/science/article/pii/S0378437109010401, the author claims that the interference pattern obtained in the double-slit experiment does not need a wave description of matter, and can be accounted for by the "quantized momentum transfer" from the slits to the electron...
  7. R

    Electron Gun diffraction and undeflected spot diameter

    Hi I am doing an electron gun diffraction right now and I wonder why the angle below is 2 phi. What I think about it that it's actually the results of two waves one is shown below and the other is a wave with the same accident angle but negative "those two rays will be symmetric around the...
  8. M

    Fourier transforms, convolution, and Fraunhofer diffraction

    I've been exposed to this notion in multiple classes (namely math and physics) but can't find any details about how one would actually calculate something using this principle: Diffraction in optics is closely related to Fourier transforms and finding the Fraunhofer diffraction of an aperture...
  9. J

    MHB Calcite X-Ray Diffraction: Find Smallest Angle

    Hello, I have a question about this optics related problem. The distance between atomic planes in calcite is 0.30 nm. what is the smallest angle between these planes and an incident beam of 30pm x-rays at which diffracted x-rays can be detected? Thank you so much for the help guys!
  10. ChrisXenon

    What is the Fundamental Reason for EMR Diffraction?

    I know the textbook definitions and descriptions of the phenomenon, but I'm hoping for a fundamental WHY. I can see that when a water wave passes an obstacle, the wave spreads out into that object's shadow because the wave's energy is not constrained to any direction and so it will move out in...
  11. Sandeep T S

    I Diffraction experiments with one particle at a time?

    Is anyone did experiment on diffraction with single particle at a time? Do they get diffraction pattern? I referred particle as both electron and photon And I want to know any experiment( classical, or single particle at time) don't show any diffraction pattern in single slit experiment.
  12. DariusP

    Varying thickness diffraction grating

    I know that a plane wave going through a slit becomes a spherical wave because of a Huygens-Fresnel principle. Can someone explain to me why a plane wave splits into many plane waves with different directions when going through a plate with varying thickness? Can someone explain me this image?
  13. T

    Deriving circular aperture diffraction

    Homework Statement i don't understand where the 1.22 number comes from like in ## sin \theta = 1.22 \lambda /D ## so i tried to derive but to not much help Homework Equations electric field at distance R due to slit of length D is ## E = \frac{\epsilon_l D}{R} sinc(\frac{kD}{2}sin \theta)sin(wt...
  14. F

    A Fresnel Diffraction - Opaque Barrier Question

    Hello! I'm very interested in knowing your opinion on how close my model is to the Fresnel Diffraction by an opaque barrier, as seen here: http://hyperphysics.phy-astr.gsu.edu/hbase/phyopt/difopa.html#c1 My model: Sorry for the low quality image.
  15. M

    Building a half-mile long photogate and fighting diffraction

    I’ve got a laser that I want to use to measure a straight line (preferably within about a millimeter) over about 2000 ft. My first thought was to focus my laser better and bring up a card until it cut the beam completely, but focusing down to a millimeter point so far away feels pretty...
  16. G

    I The 1.22 factor in the angular resolution

    Hi. The angular resolution is calculated through $$\theta=1.22\frac{\lambda}{D}\enspace.$$ It's the first zero of the intensity function (in small-angle approximation) of the Airy disk...
  17. negative

    I Diffracted photon/partice momentum

    when a single photon is supposed to form a diffraction pattern, they hit the detector by different angles at the slit. so then what cancels this photon's momentum change? what happens to the photon's energy/frequency?what measurements has been done to confirm the answer?
  18. B

    I How to interpret the diffraction envelope

    Explanations of 2-slit interference sometimes show the interference pattern compared to a 1-slit diffraction pattern, and state that the latter represents a limit or envelope for the former. Is it correct to interpret the patterns as representing (directly or indirectly) the number of photons...
  19. zehkari

    Error Calculation for a Diffraction Grating's Performance

    Homework Statement I need to calculate the error of an average value (N for diffraction grating). My results were 4 different average angles. With which I calculated their uncertainty using std. Using equation (1), I found the number of lines per meter (N) with a known wavelength (λ) and the...
  20. M

    I What are the patterns and formations seen in selected area diffraction?

    Can anyone explain me the pattern that is obtained from selected area diffraction? What does it show? What are the dots? What are the rings? (example: http://www.microscopy.cz/html/images/2605_1_d0f65ce7_fig2.png) I know that during X-ray powder diffraction, radiation is shined at the powder at...
  21. S

    Diffraction Gratings: Calculating Wavelength for CD ROM

    1. A white light shines vertically down on a horizontal CD ROM disc. The disc is viewed by a teacher whose eye is a horizontal distance 0.50 m from the disc and 0.35 m vertically above its horizontal plane, Figure 1.2. A yellow light of wavelength 590 nm is observed due to first order...
  22. C

    Bragg diffraction form an “inclined” crystal plane

    Homework Statement In picture, first-order reflection from the reflection planes shown occurs when an x-ray beam of wavelength ##0.260 nm## makes an angle ##\theta=63.8°## with the top face of the crystal. What is the unit cell size ##a_0##? Homework Equations Bragg law $$d=\frac{ n...
  23. P

    The Difference Between Diffraction And Interference Patterns

    I've recently come across this problem: Answer true or false. If light shines through 2 slits, will the diffraction pattern always be within the interference pattern. I don't understand this question, however. How can the interference and diffraction pattern be separated in this situation...
  24. S

    How Does the Fraunhofer Condition Affect Diffraction Patterns?

    Homework Statement A square aperture with a side of length 0.5 mm is illuminated with light of wavelength 550 nm. At what distance from the aperture would the Fraunhofer diffraction pattern have a central maximum with a width also equal to 0.5 mm? What can you say about the Fraunhofer condition...
  25. Beth N

    Diffraction Grating Vs Double-Slit: Small angle Approx.

    Homework Statement In double slit interference , the angle between the center bright fringe and the path length (aka the angle used to find the path length difference) can be approximate as a small angle. However, we cannot assume the angles of bright fringes due to diffraction gratings are...
  26. NihalRi

    Angle relationships of a blazed diffraction grating

    I am trying to understand how a blazed diffraction grating works and came across a deduction I don't understand. I believe that you don't need to know much about optics to answer this question as it is more geometry related. I have the diagram below of a diffraction grating with all the relevant...
  27. G

    A Fraunhofer's multiple slits versus atomic scatteres (diffraction theory)

    Hey, I am currently busy with studying solid state physics and looking at diffraction theory. Following link explains Frauenhofer diffraction pretty good: http://hyperphysics.phy-astr.gsu.edu/hbase/phyopt/mulslid.html#c3 Let's assume a N=6 multiple slits. Its diffraction pattern depends on slit...
  28. Jeremy Feng

    Young's Modulus Experiment With a Glass Screen

    Homework Statement Homework Equations Path difference is nλ at maxima, (n+0.5)λ at minima The Attempt at a Solution I think the phase difference between S1 and S2 is not 0 anymore, because the wave effectively takes a longer distance by going through S2. Thus, there is no longer a central...
  29. S

    Fraunhofer Diffraction Pattern Ratio of Power Densities

    Homework Statement Find an approximate expression for the ratio of the power densities at the principal maximum to that at the first secondary maximum on either side, in the Fraunhofer diffraction pattern of an N-slit multiple aperture. Assume that the slits are much narrower than their...
  30. Y

    Interference Fringes in a Diffraction envelope

    Homework Statement My question is at https://imgur.com/a/lDOUzjY . The de Broglie wavelength of the atoms in question is 45 pm. The distance from the slits to the detection plane is 1.95m. Each slit width is 1 micrometer. The distance between the slits is 8 micrometers. 2. Homework Equations...
  31. Erickly

    Rayleigh's Criterion + Moon (What am I doing wrong?)

    Homework Statement Suppose you wanted to be able to see astronauts on the moon. What is the smallest diameter of the objective lens required to resolve a 0.60 m object on the moon? Assme the wavelength of the light is near the middle of the visible spectrum: 550 nm yellow light. (in m) A...
  32. G

    A Diffraction on periodic Structures

    I am trying to understand diffraction on periodic structured in solid state physics.Q is the source of the spherical wave. R the vector to the object and R+r the vector to the scattering centre P, which gives us a another spherical wave. All spherical waves are considered as plane waves due to...
  33. F

    Double slits and convex lens interference

    Homework Statement Two slits (of width ##a=39 \mu m##) are lighted up with a monocromatic wave of ##\lambda=632,8 nm##. The distance between slits and the screen id ##D=4 m##. The distance between the slits id ##d=195 \mu m##. In front of the slits there are a convergent lens with focal length...
  34. C

    MATLAB FFT problem for Fresnel simulation

    Hi all, I'm trying to simulate the Fresnel diffraction by using this expersion : $$ A(x')=\frac{1}{j\lambda z}e^{jk(z+\frac{x'^2}{2z})}F(A^{trans}(x)e^{jk\frac{x^2}{2z}})_{u=\frac{x'}{\lambda z}} $$ So when I use this formula my problem is that I don't know how to take the good frequency, here...
  35. S

    Young's double slit experiment green laser

    Homework Statement If a green laser is (wavelength = 532nm) sent through two slits with a separation of 127 um, how wide (in total) would the 11 green dots formed be if they were projected onto a screen 1.25m away from the slits? Refer to this diagram sorry for bad quality...
  36. ephphatha16

    Find λ of light using a laser beam and a diffraction grating

    1. What is the advantage of using class 2 laser light? I would really appreciate if reference source is also given!Homework Equations Not needed.[/B]The Attempt at a Solution Well, I thought that using monochromatic light would made it easier to measure the distance between fringes. And also...
  37. M

    X-ray diffraction and Bragg's law

    Homework Statement The Attempt at a Solution Hi All, I have two issues with this question. First of all when I put the given values into the Bragg condition for diffraction I get two different wavelengths when the question implies there is only one. Secondly, I don't know how I can...
  38. Clara Chung

    I Question about Powder X-ray diffraction experiment

    I don’t understand why do we use power in this experiment. If we use powder, the d spacings of each crystalline will be oriented randomly, why won’t the angle of reflection changes? I don’t understand the idea of using powder in the experiment. Thank you so much
  39. M

    Diffraction Grating - Calculating Ruling Width

    Homework Statement The Attempt at a Solution Hi All! This is probably going to have a very simple answer. I'm stuck on question (b)(ii). The only equation I can find with the ruling width in it is the one shown and I can't find a way to calculate is as I don't know Beta. Thanks
  40. MermaidWonders

    MHB Solving for Slit Width-Wavelength Ratio at $\pm90°$ Diffraction Pattern

    For what ratio of slit width to wavelength will the first minima of a single-slit diffraction pattern occur at $\pm 90°$? The thing is, when I did it, I used the formula $sin\theta = \frac{n\lambda}{a}$, and used the fact that $m = 1$ and $\pm 90°$ to solve for $\frac{a}{\lambda}$. However, I...
  41. Buckethead

    Does Snell's Law accurately explain light refraction in water?

    I was reading a book called Catching the Light; a book on the history and other interesting things about light. There is a discussion in the book about refraction such as one might see when looking at a stone at the bottom of a pond when viewed at an angle. I've always just thought of the...
  42. EF17xx

    Single/double slit diffraction intensity

    Homework Statement SINGLE SLIT Why does the intensity at maxima decrease further away from the central maxima in a single slit diffraction. DOUBLE SLIT Slit width: Why is the intensity of a double slit interference pattern the same at each maxima. (constructive interference) When the slit...
  43. C

    Slit Width & Single Slit Diffraction

    Homework Statement Consider ultrasound with a frequency of 40 kHz. (a) What is the wavelength and period of a 40 kHz sound wave? (b) The slit width required to give the first order diffraction minimum at thirty degrees. (c) Calculate the angles at which the first three minimums should be...
  44. G

    Maximum Wavelength and Scattering Angle for Triangular Lattice

    Homework Statement A triangular lattice of lattice spacing ##a=2 ## angstroms is irradiated with x-rays at time zero of wavelength 20 angstroms at an incident angle of ##\alpha =135##. 1) What is the maximum wavelength of the incident x-rays? 2) What is the scattering angle ##\Omega## for...
  45. P

    I Minimizing diffraction in images using a photodetector

    If I understand the phenomenon correctly; whenever we capture an image using a telescope, because the light that's emitted from a distance object acts like a wave, we notice a diffraction pattern in our image. Now, in the double slit experiment (I didn't create the image, excuse the "slot"...
  46. A

    A level physics doubt about a Diffraction grating

    Homework Statement Monochromatic light of wavelength 690nm passes through a diffraction grating with 300 lines per mm, producing a series of maxima on a screen. What is the greatest number of maximas that can be observed? A) 4 B) 5 C) 8 D) 9 Homework Equations n*wavelength = d*sin x The...
  47. C

    Is there free software for simulating near field diffraction

    I'm looking for a free software I could use to simulate near field diffraction from a 2d periodic array of conductors and dielectrics placed on the surface of a dielectric slab.
  48. Paddyster

    How to create diffraction gratings from negative film

    Hi, I recently tried to create diffraction gratings using the negative film of a disposable camera. I designed them so the 'slits' were black and the rest was white so on the negative film the slits would be transparent and the rest would be opaque. It didn't work however. Does anybody have any...
  49. R

    Understanding Diffraction at a Single Slit: Notes and Resources

    [Mentors' note: This thread has been edited to change the level tag from 'A' to 'I'] Hello guys, I want the deduction part of- diffraction at single slit: Plz sent me the notes of this.
  50. Paddyster

    How Do Different Diffraction Grating Designs Affect Analysis Results?

    Hi, I'm doing my third year project on diffraction gratings and patterns and analysaing them via computer software and Fourier transforms. I'm going to design my diffraction gratings this week and then create them via taking a picture with a disposable camera and using the negative film. What...
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