Engineering physics polarization topic 1

Engineering physics topic of polarization

1. Wave Optics: Chapter 3-Polarization Dr. M. A. Sutar-DYPCOE 1 Fundamentals of Polarization Law of Malus Double Refraction (Birefringence) Application-LCD

2. Session 1-Polarization Dr. M. A. Sutar-DYPCOE 2 Fundamentals of Polarization Law of Malus

3. Concepts to be Recalled Dr. M. A. Sutar-DYPCOE 3 Concept of wave and direction of vibration Resolution of vector along X and Y axis

4. Objectives: Dr. M. A. Sutar-DYPCOE 4 At the end of this session, you will be able to: Concept of polarization and compare Un-polarized light and polarized light. Discriminate among PPL, CPL, EPL Describe Law of Malus

5. Dr. M. A. Sutar-DYPCOE 5 Why is Polarization important? “The only reason the polarization state of light is worth contemplating is that two beams, Otherwise identical, may interact differently with matter if their polarization states are Different” ---- Bohren (2006) Polarized wave is used by active remote sensing systems (Radar, Lidar )

6. Dr. M. A. Sutar-DYPCOE 6 Concept of Polarization

7. Dr. M. A. Sutar-DYPCOE 7 Plane Polarized light- (Vertically Polarized)

8. Dr. M. A. Sutar-DYPCOE 8 Types of Polarization

9. Dr. M. A. Sutar-DYPCOE 9 Unpolarized light (UPL) Natural light is generally unpolarized, all planes of propagation being equally probable Types of Polarization

10. Dr. M. A. Sutar-DYPCOE 10 Linearly polarized light Light in the form of a plane wave in space is said to be linearly polarized Circularly polarized light If light is composed of two plane waves of equal amplitude by differing in phase by 90° Elliptically polarized light If two plane waves of differing amplitude are related in phase by 90°, or if the relative phase is other than 90° Types of Polarization

11. Dr. M. A. Sutar-DYPCOE 11 Types of Polarization Plane polarized light Elliptically polarized light Circularly polarized light

12. In PPL vibrations are confined to one direction. In UPL vibrations are in all possible directions.

13. Dr. M. A. Sutar-DYPCOE 13 How to produce Polarized Light ? UPL PPL PPL Polariser Analyser Analyser Polariser UPL PPL No Light I. Parallel Axes II. Perpendicular Axes Max. Light

14. Dr. M. A. Sutar-DYPCOE 14 Plane of Vibration and Plane of Polarization A plane in which vibrations occurs is called plane of vibration. (In fig. it is XY plane) A plane perpendicular to plane of vibration and also contains direction of propagation is called plane of polarization. ( In fig. it is ZX)

15. Dr. M. A. Sutar-DYPCOE 15 Law of Malus Polariser Analyser E m =Amplitude of PPL incident on analyzer E= Amplitude of PPL emerging from analyzer θ= Angle between plane of transmission of polarizer and analyzer Component of PPL along axis of Analyzer is, E m cosθ which will be emerging out. Intensity is, I=E 2   Analyser Polariser UPL PPL E m E θ E m E m cosθ I α cos 2 θ This is Law of Malus E m sinθ

16. Dr. M. A. Sutar-DYPCOE 16 Summary Polarized light has unidirectional vibrations For well-defined analysis of Interference or diffraction pattern polarized light is must. Polarizer is used to produce the PPL and analyzer is used to test whether the light is UPL or PPL. When transmission planes of both polarizer and analyzer are parallel to each other then full light will be transmitted through the analyzer. However, if we keep on rotating analyzer, the intensity of the emerging light gradually decreases and becomes zero when angle reaches to 90 o . Law of Malus states that intensity of emerging polarized light is proportional to square of cosine of angle between axes of polarizer and anayzer .