Physical Optics, Wave and Oscillation



Physical optics

What is physical optics? How many theories about it?

Physical optics: The nature of light is known as physical optics.

There are two theories about the nature light

·        Corpuscular theory of Newton

·        Huygens principal [wave theory of light]

 

Mention the wave with diagram?

It is periodic disturbance in a medium or in space.

 


Define wave front?

It is the louse of all points of a medium which are vibrating in the same phase.

 

What is interference of light and types of interference with explain? Define coherent source?

Interference of light: when the two or more light waves having same frequency, same wavelength, same amplitude meet together in a medium at a point, they cancel or enhance the effect of each other that point. This phenomenon is called interference of light.

Two types of interference

·        Constructive interference.

·        Destructive interference.

Constructive interference: Constructive interference is occurred when two waves reinforce each other.

Destructive interference: Destructive interference is occurred when two waves neutralize each other

Coherent: if the waves emitted from the two light sources have same frequency and constant phase then the two sources are called coherent source.

 

Discuss the condition and use of interference?

Condition of interference:

The two sources should be coherent source.

2.  The two sources should be fine and small.

3.  The two sources should be very close each other.

4.  The amplitude of the two waves should be equal or nearly equal.

Use of interference:

1.  Signal processing.

2.  Image processing.

3.  Hologram.

4.  Wave simplification.

5.  Heat distribution mapping

6.  Radiation measurements.

7.  Light simplification etc.

Find the relation path difference and phase difference?

The difference in the phase angle and difference in path length relation can be Witten in various ways

Formula

Unit

The relation between phase difference and path difference



No units

Phase Difference


Radian or degree

Path Difference

 

Meter

 

 

 

Diffraction of light



 Define the diffraction of light and also write the condition of diffraction?

Diffraction of light: Banding of light across the edges of an obstacle is called diffraction of light.

Condition of diffraction

·       Size is obstacle.

·       Wavelength of wave

   

Write down the Classification of diffraction of light and also write the distinguished between them?

Two types of diffraction of light

·        Fraunhofer diffraction: In this type source of light and screen are at infinite distance from the obstacle.  

·        Fresnel diffraction: In this type source of light and screen are at finite distance from the obstacle.

 

Difference between Fraunhofer diffraction and Fresnel diffraction are as follows

Fraunhofer

Fresnel

In this source of light and screen are at infinite from the obstacle.

In this source of light and screen are at finite from the obstacle.

Incident wave front on the aperture is plane.

Incident wave front on the aperture is cylindrical.

The diffracted wave front is plane.

The diffracted wave front is cylindrical.

Mathematical treatment is easy.

Mathematical treatment is not easy.

It has many applications in designing of optical instrument. 

It has less applications in designing of optical instrument.

The maximum and minimum are well defined.

The maximum and minimum are not well defined.

 

 Distinction between Interference and diffraction.

Difference between interference of light and diffraction of light are as follows

Interference

Diffraction

Interference happens because of the superposition of two waveforms coming from two different coherent sources.

Diffraction happens because of the superposition of secondary wavelets from the different path of wave front.

The width of the fringes in interference is equal.

The width of the fringes is not equal in diffraction.

The contrast between maxima and minima is good.

The contrast between maxima and minima is poor.

Fringe spacing is uniform in interference.

Fringe spacing is non-uniform in diffraction.

 

 

Polarization of light

What is polarization and unpolarized light?

Polarization: When the vibration of light in one direction such as up and down is called polarized light.

Unpolarized light: When the vibration of light in many directions such as up or down and lift or right is called unpolarized light.

 

Distinguish between ordinary light (un-polarization light) and polarized light?

 

Difference between polarization and un-polarization of light are as follows-

Polarized light

    Unpolarized light

When the vibration of light in one direction such as up and down is called polarized light.

When the vibration of light in many directions such as up-down and lift-right are called unpolarized light.

Asymmetrical about the ray direction.

Symmetrical about the ray direction.

It is obtained from unpolarized light

Produce by conversional light source.

 

What is type of polarized light?

There are three types of polarization of light

·        Linear polarization.

·        Circular polarization.

·        Elliptical polarization.

 

What is plane polarization?

A plane in which electromagnetic radiation vibrates when it is polarized so as to vibrate in a single plane.

 

Where the applications of polarization?

Follows are the application of polarization

·        Polarization is used in sunglasses.

·        Polarization is used in 3D movies.

·        Communication and radar application.

 

Active optical substance

·        Produce polarized light.

·        Rotated the plane of polarization and polarized light.

·        Produce double refraction.

·        Convert the plane polarized light into circularly polarized light.