Optics: Fraunhofer diffraction - adjustable slit | MIT Video Demonstrations in Lasers and Optics

Optics: Fraunhofer diffraction - adjustable slit
Instructor: Shaoul Ezekiel
View the complete course: ocw.mit.edu/RES-6-006S08
License: Creative Commons BY-NC-SA
More information at ocw.mit.edu/terms
More courses at ocw.mit.edu

[@kirknay]

I found this after PBS's latest Spacetime video mentioned using your index and middle fingers over your eye to see something similar.

[@prof_hu]

Same for me.

[@KartikSharma1607]

relly nice. Helping me a lot in college. Thanks

[@jakobberzins3855]

The diffusion must occur at the edges of the slit, which makes diffraction occur for a single slit because of 2 edges. Not many sources explain this well.

[@jakobberzins3855]

I wonder if when physicists detect which slit in the double slit experiment if they are just destroying the coherence of the light. Hence no diffraction pattern.

[@vishnoinigam1648]

in second video with circular apertures when he vary the distance between pinhole and slit then why it happens so that when he reduces the distance there are larger fringes and when he increases it there are fewer fringes

[@bellinivernon]

Exelente !

[@sidewaysfcs0718]

when the distance between two null minimums is about 2.5 cm, the slit width is 50 micrometers

[@samarthd9948]

Yes sir, you're right

[@siddharthgandhi7937]

Thanks

[@pranayreddy007]

fraunhofer diffraction means rays diffractio of ray by using converging lens and and usual diffraction means without any lens

[@thewanderers97]

Enlightening

[@sussusamogus8860]

Brilliant

[@NikitaNair]

Wow!!!

[@shahramshahram412]

Light concentrators make the strips

[@anshukumar-yn4yn]

Is convex lens used for focussing wave front after passing through slit????

[@puhbrox]

All I'm getting from this is that light is really powerful and it's bouncing off the slit in a way that makes it divide (but in reality it's just because the light is not a particle dividing but a wave dividing)

[@alcatraz766]

Interesting theory but I'm afraid you're wrong, it actually due to the wave nature of light, the bright spots represent the spots with constructive interference and the blank ones representing the destructive interference.

[@Sushil2k4]

[@anupamsuman4037]

is there any specific reason to use reflection of the laser light?

[@jhyland87]

I was wondering that as well.

[@mielole]

I think the laser was too long to fit in front of the slit and, additionaly, was obstructing the slit. Thus, it was moved and a reflection system was put in place. It works just as well with direct light.

[@trk3294]

We use this technique generally to allow the laser beam to diverge and increase its spot size by allowing it to have a longer optical path. This technique is described by the far field radiation pattern which is a region of the electromagnetic field. And the parameters such as Power radiated, radiation intensity, Power pattern, Directivity, Gain etc are calculated from Far field.

[@manavshetty4449]

The reason is simple. It is to create a huge distance btw the slits and the source.... as for fraunhofer diffraction huge distances are required

[@anshikapal8884]

Laser light is more coherent than ordinary light .

[@zenvir1680]

I did this experiment at home with a lazer and slit made by sticking two razor blades with tape.

[@simranbaghla3381]

Zen vir grt

[@thorsten8554]

Did this too today ! --> kzbin.info/www/bejne/fp3WhICof5eFfac

[@rainbow1000ish]

Can anybody tell me what's the difference between Fraunhofer diffraction and the diffraction at a normal way??

[@coffeedence1511]

I'm not sure, but I would say that the difference is in the approximation of Fresnel-Kirchoff equation. If I'm not wrong, the Fraunhofer diffraction is an approximation valid when the source (the incident waves are plane waves (in this case the Laser Beam)) and the screen (In this case 200 cm) are very far from the slit. If the screen is near to the slit and the incident waves are spherical, we've got Fresnel Diffraction.

[@jamesprince9041]

How do we know that the interference pattern is not the result of quanta particles following the pattern of gravitational waves between the source and target. If gravitational waves exist, the duality of light quanta as both a wave and particle will be negated, a light particle would only appear as a wave as it traverses the valleys and crests of gravitational waves, because light is bound to gravity. Light is affected by gravity, gravity affects spacetime, and photons must follow a path in spacetime. As spacetime curves the path photons take is changed

[@parisian9933]

No offense intended but he looks and speaks a bit like Howard Wolowitz xD Great Content btw :)

[@manjuldahal440]

n

[@mortirius1]

Im a little confused I thought it was only supposed to have two areas of light intensity when the double slit is observed but here I'm seeing a diffraction pattern thats only supposed to happen when there is no observer. Can someone explain why

[@snehalsha6476]

allan J this is not the quantum scale

[@jamesovenden3833]

His voice reminds me of the european immigrants that aren't quite american on family guy

[@aditya_asundi]

Aaditya sir if you're watching this, hi 👋

[@ahmadmuaz5360]

Boleh dh aq belajaq kat mit😤

[@leewilliam3417]

Mmmmm😊

[@zenext7764]

Improve video quality , guys.

[@anoopkrishna20000]

Vdeo ws 8 yrs ago

[@rainbow1000ish]

Can anybody tell me what's the difference between Fraunhofer diffraction and the diffraction at a normal way??

[@antiTamtaSquadLeader]

In the case of fraunhofer diffraction the wavefront is a plane wavefront that means the light source is at infinity. If the "normal" case is of diffraction of light of a source at infinity then it is fraunhofer but if there is a finite distance then it's fresnel diffraction

[@rainbow1000ish]

@@antiTamtaSquadLeader oh God this comment is 7 years old

[@1eV]

@@rainbow1000ish feeling old? XD

[@rainbow1000ish]

@@1eV omg this is 7 years old Now i have no idea what i was even asking about 😂🤣🤣

[@1eV]

@@rainbow1000ish understandable