Total Internal Reflection and Critical Angle

Total Internal Reflection and Critical Angle

1. Total Internal reflection and criticalangle Presented By:- Amit Raikar

2. What is Refractive Index? The refractive index of a medium is defined as the ratio of the velocity of light in a vacuum to the velocity of light in the medium . A ray of light travels more slowly in an optically dense medium than in one that is less dense.

3. What is Refraction? When a ray is incident on the interface between two dielectrics of differing refractive indices (e.g. glass–air), refraction occurs

4. As the angle of incidence I ncreases , the angle of refraction Increases .

5. What is Critical Angle? At a certain angle, the refracted ray follows a path exactly along the surface of the dense medium. When the angle of refraction is at 90° the incident angle is called the “ Critical Angle ”

6. What is Total Internal Reflection (TIR)? If the incident ray is increased beyond the critical angle, the light is no longer refracted • Instead, it is reflected back inside the medium • This is called “ total internal reflection”

7. Total Internal Reflection A light ray hits the inside face of a semicircular block.

8. Total Internal Reflection

9. Conditions for TIR & Critical Angle Light is travelling slower in the first medium than in the second medium (v1 < v2 ) Thus light is moving from medium of higher refractive index to one of lower refractive index (n1 > n2) Critical angle (C) is defined when the angle of refraction is 90° to the normal (θ2 = 90°) TIR occurs when angle of incidence is larger than the critical angle ( θ 1 > C)

10. Calculating Critical Angle

11. Critical angles of different materials Medium Refractive Index Critical Angle Glass 1.50–1.70 30°–42° Water 1.33 49° Perspex 1.5 42° Diamond 2.42 24°

12. Applications of TIR TIR in Fiber Optics C ommunication Endoscopes TIR in Prism Periscopes Binoculars Single Lens Camera Retro Reflectors

13. Communication

14. Endoscopes

15. Periscopes

16. Binoculars

17. Single Lens Camera

18. Recto Reflectors

19. Thank You!