1. Multiple Beam Interference

2. Optical Reversibility and Phase Changes on Reflection
G.G. Stokes used the principle of optical reversibility to investigate the reflection of light at an interface between two media.
The reversibility principle states that
If there is no absorption of light , a light ray that is reflected or refracted will retrace its original path if its direction is reversed.

3. © SPK

4. Thin films: multiple beam interference
© SPK

5. Optical field in reflected beam
: the incident wave

6. Resultant reflected scalar wave

7. Reflected irradiance

8. Optical field in transmitted beam

9. Transmitted irradiance

11. For Transmitted rays

12. For Reflected rays

13. Coefficient of Finesse

15. Airy function A

16. I0 d

17. IR/I
IT/I d

18. Types of localization of fringes

19. Interference fringes
Real
Virtual
Localized
Non-localized

20. Localized fringe
Observed over particular surface
Result of extended source

21. Non-localized fringe
Exists everywhere
Result of point/line source

22. POHL’S INTERFEROMETER
Real
Non-localized
Virtual
Localized

23. Newton’s Ring
U<<R & U>>d

25. Interference filter

26. An interference filter is designed for normal incidence of 488 nm light.
The refractive index of the spacer is What should be the thickness
of the spacer for normal incidence of light.
It will pass different wavelength if the angle of incidence is not 90o.

27. Reference
1. Optics
Author: Eugene Hecht
Class no. 535 HEC/O
Central library
IIT KGP