2. Olomouc 2017
Light interferometry
Pavel Pavlíček

3. Welcome speech

4. Welcome speech

5. Light interferometry
Interferometry : technique
Interference : phenomenon

6. Interferometry : technique
Interference : phenomenon
crest cresta hřeben
trough ventre brázda

7. Interference is a phenomenon in which two waves superpose
anatomy of a wave
crest cresta hřeben
trough ventre brázda

8. Superposition of waves

9. Superposition of waves

10. Superposition of waves

11. Superposition of waves

12. Superposition of waves

13. Superposition of waves

14. Superposition of waves

15. Superposition of waves
in phase

16. Superposition of waves
in phase

17. Superposition of waves

18. Superposition of waves
out of phase

19. Superposition of waves
out of phase

20. Interference
continuum of possibilities
between „in phase“ and
„out of phase“
out of phase
in phase
wave of zero amplitude
giant wave
constructive interference
destructive interference

21. Interference

22. waves are superimposed => information about the waves

23. Michelson interferometer (1880s)
Light source
Detector

24. Michelson interferometer
Light source
in phase I
~10-4 nm
Detector l

25. Michelson interferometer
Light source
l/4
out of phase
Detector

26. Michelson interferometer
Light source
l/2
in phase
Detector
l/4
l/2
(3/4)l l

27. Classical interferometry
How does it work?
CCD
l/4
l/2
light source
measured object

28. How does it work?
CCD
l/4
l/2
light source
measured object

29. Michelson-type interferogram
phase the deviation of the measured surface from the reference plane y x

30. A problem: ambiguity

31. Michelson interferometer
Light source I
in phase
~ nm
Detector l

32. Michelson interferometer
Light source
l/4 I
out of phase
~ nm
Detector l

33. Michelson interferometer
Light source
l/2
in phase
Detector
l/4
l/2
(3/4)l l

34. Spectra and interferograms of various sources
~10-4 nm z l I I
~ nm l z I I
~ 1200 nm l z

35. Measured interferogram of He-Ne laser (l = 633 nm)
45 mm

36. Measured interferogram of He-Ne laser (l = 633 nm)
45 mm

37. Measured interferogram of He-Ne laser (l = 633 nm)
45 mm

38. Measured interferogram of a LED (diodo ad emissione luminosa)

39. Measured interferogram of a LED (diodo ad emissione luminosa)

40. Measured interferogram of a LED (diodo ad emissione luminosa)

41. Measured interferogram of an incandescent lamp
(lampadina)
intensity
path difference

42. White-light interferometry
How does it work?
CCD
light source
measured object
reference mirror

43. How does it work?
CCD
light source
measured object
reference mirror

44. How does it work?
CCD
light source
measured object
reference mirror

45. How does it work?
CCD
light source
measured object
reference mirror

46. Measured height profile
height profile coded
by gray scales
cross section along the
horizontal line
100 mm

47. Measured interferogram and its envelope
74.7 mm
111.9 mm

48. Thank you for your attention