2. Refractive index
Petr Šafařík

3. Petr Šafařík Masaryk university: Astrophysics
Institute of Scientific Instruments: Coherence Optics
ICQ:

4. Outline Theory of the refractive index
Methods of measuring refractive index
My results at ISI Brno
Summary
Questions

5. Outline Theory of the refractive index
Methods of measuring refractive index
My results at ISI Brno
Summary
Questions

6. Theory Definition of refractive index: Usually given the symbol
The refractive index of a medium is defined as ratio of the phase velocity in the reference medium to velocity in the medium itself.
Reference medium: usualy vacuum.
Usually given the symbol

7. Theory
In case of light:

8. Phase & group velocity
The phase velocity of a wave is the rate at which the phase of the wave propagates in space. This is the velocity at which the phase of any one frequency component of the wave will propagate. You could pick one particular phase of the wave (for example the crest) and it would appear to travel at the phase velocity. The phase velocity is given in terms of the wave's angular frequency ω and wave vector k by:
V_p = omega / k
The group velocity of a wave is the velocity with which the variations in the shape of the wave's amplitude propagate through space.
V_g = partial derivation omega by k

9. Outline Theory of the refractive index
Methods of measuring refractive index
My results at ISI Brno
Summary
Questions

10. Outline Theory of the refractive index
Methods of measuring refractive index
My results at ISI Brno
Summary
Questions

11. Methods of measuring Indirect – Edlén‘s formula
Direct – Laser refratometer

12. Methods of measuring Indirect – Edlén‘s formula
Direct – Laser refratometer

13. Indirect – Edlén‘s formula
p – pressure
t – temperature
(s-1) – dispersion coefficient

14. Weather bureau

15. Methods of measuring Indirect – Edlén‘s formula
Direct – Laser refratometer

16. Methods of measuring Indirect – Edlén‘s formula
Direct – Laser refratometer

17. Laser refractometer
Michelson‘s interferometr:

18. Laser refractometer Refractometr based on Michelson:
D - detector, L – laser, M – Mirror
VP - Vacuum pump, VM - Vacuum meter , VS- Vacuum sensor

19. Laser refractometer
Examples of interference fringes:

20. Fabry-Perot based refractometer
Scheme:

21. Outline Theory of the refractive index
Methods of measuring refractive index
My results at ISI Brno
Summary
Questions

22. Outline Theory of the refractive index
Methods of measuring refractive index
My results at ISI Brno
Summary
Questions

23. My results
Scheme:

26. Outline Theory of the refractive index
Methods of measuring refractive index
My results at ISI Brno
Summary
Questions

27. Outline Theory of the refractive index
Methods of measuring refractive index
My results at ISI Brno
Summary
Questions

28. Summary
Light rays chanfe direction, when they cross the interface from material to other one by the Snellius law:
Light reflects partially from surfaces, that have refractive index fifferent from that of their suroundings.

29. Outline Theory of the refractive index
Methods of measuring refractive index
My results at ISI Brno
Summary
Questions

30. Outline Theory of the refractive index
Methods of measuring refractive index
My results at ISI Brno
Summary
Questions

31. Questions
Your time…