How Do Infinite and Finite Light Sources Produce Different Wavefront Shapes?

In summary, light sources in isotropic mediums at infinity produce plane wavefronts due to the zero curvature of an infinitely large sphere, while linear sources such as a slit produce cylindrical waves due to their description as a linear sum of harmonic functions. This is caused by diffraction.
  • #1
Kehsibashok
15
0
1.how and why does a light source in an isotropic medium at INFINITY produces PLANE Wavefronts instead of CIRCULAR Wavefronts as in case , when a light source is in the same isotropic medium but at FINITE distance?

2.how and why does a linear source of light such as a slit illuminated , produces CYLINDRICAL waves?
 
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  • #2
1. Spherical wavefronts change into plane wavefronts at infinity, because the radius of the sphere grows with the distance. A sphere with infinite radius has zero curvature: it is a plane.

2. This is caused by diffraction.
 
  • #3
We can describe any (scalar) field as a linear sum of harmonic functions, be they planar (cartesian), cylindrical or spherical.

For example, a plane wave can be described as a sum of cylindrical harmonics. A cylindrical harmonic can conversely be described as a sum of plane waves.

Claude.
 

Related to How Do Infinite and Finite Light Sources Produce Different Wavefront Shapes?

1. What is a plane wavefront?

A plane wavefront is a type of wavefront that is characterized by a flat, planar shape. It is a type of propagating wave that has a constant phase across the entire wavefront, meaning that all points on the wavefront are in phase with each other.

2. How does a plane wavefront differ from a spherical wavefront?

A spherical wavefront is a type of wavefront that has a curved, spherical shape. Unlike a plane wavefront, a spherical wavefront has varying phases across its surface, with points closer to the center of the wavefront being in phase earlier than points further away.

3. What is a cylindrical wavefront?

A cylindrical wavefront is a type of wavefront that has a curved, cylindrical shape. It is similar to a spherical wavefront, but instead of being curved in all directions, it is only curved in one direction, forming a cylindrical shell.

4. How are plane and cylindrical wavefronts used in practical applications?

Plane and cylindrical wavefronts are commonly used in optics and acoustics to describe the propagation of waves. They are also used in medical imaging techniques, such as ultrasound, to create a focused beam of waves that can be used to produce images of internal structures in the body.

5. Can wavefronts be manipulated?

Yes, wavefronts can be manipulated through the use of lenses, mirrors, and other optical elements. These elements can change the shape and direction of the wavefront, allowing for the creation of images, correction of vision, and other applications.

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