Single slit diffraction

Interference, refraction, reflection, and diffraction are all examples of processes that occur as light travels through air. When light comes into touch with an impediment, it diffracts.

The wavefront on the other side of the opening mimics the wave when light flows through a small opening that is comparable in size to the wavelength of the light. Please explain light diffraction and single slit diffraction, which occurs when light passes through a single slit. Let’s also have a look at what happens in a single slit diffraction experiment. When light passes through a single slit with a width (w) on the order of the wavelength of the light, we can witness single slit diffraction. The diffraction pattern on the screen will be L >> w from the slit. The angle is proportional to the intensity.

Interference effects occur in the space downstream of a slit that is wider than a wavelength. These can be explained by supposing the slit operates as if it contains a large number of point sources evenly spread across its width. When we examine light of a single wavelength, the analysis of this system is simplified. These sources have the same phase if the incident light is coherent. Light incident at a particular location in space downstream of the slit is made up of contributions from each of these point sources, and we should expect to detect minima and maxima in the diffracted light if the relative phases of these contributions vary by 2 or more.

Diffraction Definition

The bending of light around corners such that it spreads out and illuminates places where a shadow is expected is known as diffraction. In general, it’s difficult to distinguish between diffraction and interference because they both happen at the same time. Diffraction of light is responsible for the silver lining we see in the sky. A silver line appears in the sky as sunlight penetrates through or hits a cloud. When Young’s double-slit experiment is replaced with a single narrow slit, a broad pattern with a brilliant patch at the centre appears. There are alternating dark and bright zones on both sides of the centre. As you travel out from the centre, the intensity drops. This article goes over single slit light diffraction in great detail.

What is Single Slit Diffraction and how does it work?

We may examine the bending phenomena of light, or diffraction, in the single-slit diffraction experiment, which causes light from a coherent source to interfere with itself and generate distinct patterns on the screen termed the diffraction patterns. Diffraction happens when the sources are small enough to be comparable in size to the wavelength of light. 

Single Slit Diffraction Formula

The slit width will be assumed to be a<<D, and the distance between the slit and the source will be x.

The angular position of any point on the screen will be determined by measuring from the slit centre, which splits the slit by a/2 lengths. To explain the pattern, we’ll look at the condition of black fringes first. Let’s also divide the slit into a/2 zones of equal widths. Let’s look at a pair of rays that come from a/2 distances apart, as indicated below.

The top two rays show the following route difference:

∆L= a2sinθ

Remember that this is only a valid computation if D is really large. Check visit our article on Young’s Double Slit experiment for more information on the approximation.

Any number of ray pairs that begin at a distance can be considered.

The bottom two rays in the diagram, for example, are separated from one another. At a distance a2, any arbitrary pair of rays a2 can be taken into account In a moment, we’ll discover how important this trick is.

The path difference must induce destructive interference for a dark fringe; the path difference must be 2 out of phase.

The first fringe is made up of

L=2=a2sinθ

λ=a sinθ

There is another beam at a distance for any ray emerging from any point in the slit.

This may result in harmful interference.

As any ray emerging from a point has a counterpart that produces destructive interference, there is destructive interference at θ = sin-1/a. As a result, a dark fringe is created.

We can divide the slit into four equal sections of a/4 and use the same rationale for the next fringe. As a result, for the second minimum:

nλ=a sin

The central maximum

The maxima are located between the minima, and the width of the central maximum is equal to the distance between the first order minima on both sides of the screen.

The position of the minima determined by y (as measured from the screen’s centre) is:

tanθ ≈ θ ≃ yD

For small ,

sin ≈

λ=a sinθ ≈ aθ

θ=yD=λa

y=λDa

Conclusion

• In this article we learned to get maxima and minima for diffraction.

• We learnt how to compute diffraction values for two slits in two ways: the traditional technique with big angles and the small angle approximation.

• We learned how to use this technique with single slits.