Diffraction grating Definition and 22 Discussions

In optics, a diffraction grating is an optical component with a periodic structure that splits and diffracts light into several beams travelling in different directions. The emerging coloration is a form of structural coloration. The directions of these beams depend on the spacing of the grating and the wavelength of the light so that the grating acts as the dispersive element. Because of this, gratings are commonly used in monochromators and spectrometers.
For practical applications, gratings generally have ridges or rulings on their surface rather than dark lines. Such gratings can be either transmissive or reflective. Gratings that modulate the phase rather than the amplitude of the incident light are also produced, frequently using holography.The principles of diffraction gratings were discovered by James Gregory, about a year after Isaac Newton's prism experiments, initially with items such as bird feathers. The first man-made diffraction grating was made around 1785 by Philadelphia inventor David Rittenhouse, who strung hairs between two finely threaded screws. This was similar to notable German physicist Joseph von Fraunhofer's wire diffraction grating in 1821. Gratings with the lowest line-distance (d) were created, in the 1860s, by Friedrich Adolph Nobert (1806–1881) in Greifswald; then the two Americans Lewis Morris Rutherfurd (1816–1892) and William B. Rogers (1804–1882) took over the lead; and, by the end of the 19th century, the concave gratings of Henry Augustus Rowland (1848–1901) were the best available.Diffraction can create "rainbow" colors when illuminated by a wide-spectrum (e.g., continuous) light source. The sparkling effects from the closely spaced narrow tracks on optical storage disks such as CDs or DVDs are an example. Similar rainbow effects seen in thin layers of oil (or gasoline, etc.) on water are not caused by a grating but rather by iridescence in reflections from the closely spaced transmissive layers. A grating has parallel lines, while a CD has a spiral of finely spaced data tracks. Diffraction colors also appear when one looks at a bright point source through a translucent fine-pitch umbrella-fabric covering. Decorative patterned plastic films based on reflective grating patches are very inexpensive and commonplace.

View More On Wikipedia.org
  1. L

    Number of bright fringes given by diffraction grating on a screen

    (1) In the book I am using the separation of bright fringes is indicated as being ##\Delta y=\frac{\lambda}{d}##, where ##d## is the separation of the slits so on a screen of width ##W## I would see ##\frac{W}{\frac{\lambda}{\frac{1}{N}}}## bright fringes. I don't see why the text of the...
  2. warhammer

    Question on Resolving Power of Diffraction Grating

    I have doubts about my work for the second part of the question, where I am asked if resolution will be possible or not. For the first part, I calculated No. of lines N=6.43*10^2 lines/cm For the second part, I have attached below a snapshot of my neatly written work. I request a PF member to...
  3. 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...
  4. M

    Optics - Diffraction grating

    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
  5. I

    What is the wavelength difference based on a mini spectrom.?

    Homework Statement I'm a bit stuck on how to approach this problem. A miniature spectrometer used for chemical analysis has a diffraction grating with 800 slits/mm set 25.0 mm in front of the detector "screen." The detector can barely distinguish two bright lines that are 30 μm apart in the...
  6. Paddyster

    How does the diffraction grating in Canadian currency work?

    Hi, This is my first post so apologies if I'm not clear enough or if I am posting in the wrong place. I am doing my 3rd year project at university and I am creating diffraction gratings. My supervisor shown me a Canadian note and if you shine a laser through the maple leaf it will shine on the...
  7. C

    More slits, farther maxima of interference patterns, why?

    When observing interference patterns, one will notice that the maxima from a double slit are more intense and farther apart than the maxima of a single slit. Likewise, the maxima from a diffraction grating are more intense and farther apart than maxima of a double slit. Why is this? I...
  8. A

    Single Slit and Diffraction Grating Formulas

    Hi everyone. I am having some difficulty understanding the formulas of single slit diffraction and diffraction gratings. This is partly because the formulas that I have been given in class do not reflect what I have found online entirely. As we know, the formula for single slit destructive...
  9. A

    Diffraction Grating and White Light Problem

    Homework Statement White light containing wavelengths from 400 nm to 750 nm falls on a grating with 6000 lines/cm. How wide is the first-order spectrum on a screen 2.0 meters away Homework Equations dsinθ=mλ for constructive interference dsinθ=(m+1/2)λ for destructive interference Δx = λL/d...
  10. T

    Maximum frequency if there is to be one diffraction order

    Homework Statement A naval towed-array sonar comprises a line of ##80## transducers, equally spaced over a total length of ##120 m##, that is towed behind a ship so that it lies in a straight line just below the surface of the water. An adjustable phase delay can be introduced electronically...
  11. S

    Fraunhofer diffraction experiment- neural density filters

    I'm currently carrying out an experiment with Fraunhofer diffraction. It involves shining a laser beam through neural density filters, a lens and a diffraction grating, to create a diffraction pattern which is then picked up with a CCD camera, to find the intensity of the maximal peaks. However...
  12. Z

    Investigation about the emission spectrum of Mercury

    Homework Statement For our investigation, we used a diffraction grating spectrometer to observe the emission spectrum of mercury. We conducted the experiment in a pitch black room to avoid any unwanted light pollution, etc. Whilst conducting the experiment we observed a number of 'faint' lines...
  13. H

    Two Diffraction Gratings - Rotation

    Can someone explain how the laser pointer is generating the rectangular patterns shown in this youtube video? I assume that there are just two diffraction gratings that are rotated relative to each other, but could someone explain mathematically how to predict what pattern is formed for...
  14. EmilyBergendahl

    Calculating the Number of Lines on a Diffraction Grating

    Homework Statement A diffraction grating gives a second-order maximum at as angle of 31° for violet light (λ = 4.0 × 10^2 nm). If the diffraction grating is 1.0 cm in width, how many lines are on this diffraction grating? Homework Equations d = (m)(λ)/sinθm The Attempt at a Solution d =...
  15. EmilyBergendahl

    The Diffraction Grating (Grade 12 Physics)

    Homework Statement Do the maxima created by a diffraction grating all have the same intensity? Explain. Homework Equations mλ = wsinθ (?) The Attempt at a Solution According to the back of my textbook (Nelson Physics 12), the answer is no. I believe the answer may have to do with the fact...
  16. Tazerfish

    Strange Optical Phenomenon (diffraction or something else?) (solved)

    First of all i will post a picture of it ... you can find it ... somewhere sorry this is my first post :I I photographed our television with the flash on in order to recreate a strange patter i saw when looking at the suns reflection in the screen.(with my eyes it's not just the camera) You can...
  17. kamhogo

    Single-sit vs. Double-slit vs. Diffraction grating

    Homework Statement Briefly state one characteristic of single-slit /double-slit/diffraction grating interference pattern that allow you to clearly distinguish one from the others. Homework Equations None The Attempt at a Solution Single-slit: Taller, broader central maximum. Double-slit...
  18. toforfiltum

    Diffraction grating that gives max intensity

    Homework Statement Homework Equations dsinθ=nλ IαA2 The Attempt at a Solution I chose D because I thought that D gives the max intensity since the amplitudes superimpose over a smaller area. But the answer is C. I can't see why.
  19. Shahab Mirza

    Diffraction Grating Problem ?

    Hi, 1. Homework Statement Q : A diffraction grating with 10000 lines per CM is illuminated by yellow light of wavelength 589 nm, At what angles is the 2nd order bright fringes seen ? Homework Equations From my textbook , I got this equation , d sin theta = m (λ) The Attempt at a Solution Ok...
  20. CAH

    Where is fringe spacing measured from with white light?

    Fringe spacing is the distance between two adjacent maxima or minima. For white light, is a maxima the distance from red to red (green to green, blue to blue..)? or the middle of the maxima to another middle of another maxima (i see that this distance will be the same since its middle to middle...
  21. HaLAA

    Find the speed of a galaxy

    Homework Statement Taking light collected by the telescope and shine it through a diffraction grating with a 765.5 lines/mm. Using the filter that just the brightest Helium II line. you cast the diffraction grating's diffracted pattern on a screen is 22.000cm away and there are 3 dots, m=-1...
  22. W

    Problem with wave optics - diffraction grating?

    Homework Statement For your science fair project, you need to design a diffraction grating that will disperse the visible spectrum (400-700nm) over 30 degrees in first order. How many lines per mm does your grating need? Homework Equations sin(Θ) = mλ/d y = Ltan(Θ) I'm pretty sure the only...