# Wave Front

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A wavefront meaning is, it is the set or locus of all the points in the same phase. Here, the locus is the path travelled by a particular point emanating from the light source; however, there are millions of points like this.Â  All these points undergoing locus form various types of wavefronts.

There are three types of wavefront, viz: plane wavefront, spherical wavefront, and cylindrical wavefront. Moving forward, we will understand these types with the wavefront Physics and Wavefront Lasik in detail.

## Wavefront Meaning

A wavefront meaning is, it is the front of a propagating wave, or we can say, it is the edge where conditions start to deviate from equilibrium.

This definition can be better understood by the following statement on Psychological theory stated by Throndike.

In his experiment, he locked a hungry cat inside the cage and there was a mechanism to open that box. However, due to the lack of practice and new to the path, the cat could not find the way out.Â

Here, the cat deviates from its original path and keeps on making varying shapes by moving here and there.

Since the cat or a point source keeps on running (madly striving for food) in the same phase (the box), Also, the cat makes various feet impressions on the surface of the box, so we can say that these impressions are point sources where each of these makes varying shapes and these varying shapes are wavefronts viz: planar, spherical, and cylindrical.

### Wavefront in Physics

So, basically, wavefront is the surface containing points affected in the same way by a wave at an instant.

In physics, the wavefront of a time-varying field is the path of all the points where all sinusoidal waves lie in the same phase. The term â€˜wavefrontâ€™ is meaningful for fields vary sinusoidally at each point in time â€˜tâ€™ with a single temporal frequency.

### Wavefront Physics

Wavefronts usually proceed with time. For waves travelling in one-dimensional medium/place, the wavefronts are usually single points; they are curves in a 2-D medium, and surfaces in a 3-D one.

For a sinusoidal plane wave, the wavefronts are planes perpendicular to the direction of propagation that moves in the direction together with the wave. For a sinusoidal spherical wavefront, the wavefronts are spherical surfaces that expand with it.Â

If the speed of propagation varies at different points of a wavefront, the shape and/or orientation of the wavefronts may differ by refraction. In particular, lenses can change the shape of wavefront optical from planar wavefront to the spherical wavefront, or vice versa.

Below is the visual representation of the sinusoidal wavefront:

## Types of Wavefront

As we know that the path taken by points emanating from the light source leads to the different types of wavefront. Now, letâ€™s discuss these types in detail:

• ### Spherical Wavefront

Thus, a spherical wave front is the front of a propagating wave that has the shape of a ball.

As we look at the image below, we can see that point sources have a spherical shape.

Now, the definition of the spherical wavefront is as follows:

All spherical wavefronts of sound waves spread in all the directions from a point source. Electromagnetic waves in vacuum also form a spherical wavefront.

Examples:Â

1. On throwing a stone in the water, we see the interference nature of water ripples and these continuous formations of concentric circles is the spherical wavefront.

2. An army man watching the enemy on radar through the camera locates the intruder with the symbol of spherical wavefront.

### Cylindrical Wavefront

We obtain a cylindrical wave front when the source of waves is a line source, i,e, it is similar to a lightsaber. A cylindrical wave front sees like a cylinder; however, if we draw the wavefront for one plane, we obtain a concentric circle and that is the spherical wavefront.

Plane Wavefront

Planar wavefront or a plane wave has a constant wave phase along a planar surface or the wavefront. As time evolves, the wavefronts propagate at the constant wave speed. At this moment, we say that the wavefronts are invariant to propagation in this case.Â

### Wavefront Lasik

LASIK is an acronym for Laser-assisted in-situ keratomileusis. It is the simplest, quick, and effective treatment for refractive errors in the human eye.Â

Wavefront LASIK is also called custom LASIK. It is a modern approach to LASIK, a procedure that uses guided lasers to reshape your cornea and improve your visual sharpness.

By using a wavefront device, your eye surgeon measures aberrations in your corneaâ€™s shape and texture, and then customize the lasers to treat all these aspects of your cornea. This improves your vision, your ability to see well at night, and your ability to distinguish among the contrasting colours.Â

Wavefront guided LASIK also reduces the side effects associated with traditional LASIK.

Through the Wavefront Guided LASIK,Â  a person can be cured of the following vision issues with the help of surgery:

• Myopia or nearsightedness

• Presbyopia and Hypermetropia - farsightedness, and

• Astigmatism

Q1: What are Wavefronts? Explain with an Example.

Ans: A wavefront is a place over which an optical wave has the same phase. For example, a wavefront is a surface over which the crest of the sinusoidal water wave has a maximum value and the trough of the water wave has a minimum value. Also, these waves lie in the same phase.

According to the Huygenâ€™s principle, the wave nature of wave propagation of the light waves: Every point on a wavefront is the secondary spherical wavelet that spreads in the forward direction at the speed of light. The new wavefront is formed out of the tangential surface to all these secondary wavelets.

Q2: What is the Wavefront Aberration?

Ans: In an optical system, the deviation of a wavefront from the perfect planar wavefront is called the wavefront aberration. Wavefront aberrations are usually described as both the sampled image and the collection of two-dimensional polynomial terms. Minimization of these aberrations is possible for many applications in optical systems by using guided treatments like Wavefront-guided LASIK.

Q3: State Three Advantages of Wavefront LASIK.

Ans:Â

1. Precise correction of eyes refractive errors.

2. Lessens higher-order aberrations.

3. Improves issues with contrast sensitivity, seeing black letters on a white background.