A BRIEF EXPOSURE TO INTERFEROMETERS AS PER ANNA UNIV SYLLABUS

1. LASER INTERFEROMETER

2. LASER INTERFEROMETER What’s laser interferometer? The principle of standard interferometer Types of interferometers Applications

3. What’s a Laser Interferometer? Laser Interferometer: the instrument used for high precision measurements (distance, angles…. etc.) it uses interferometry as the basis for measurement. it uses the very small, stable and accurately defined wavelength of laser as a unit of measure.

4. Physics Review Interference of Light

5. LASER INTERFEROMETRY Brief Description of components (i) Two frequency Laser source (ii) Optical elements: a) Beam splitter: b) Beam benders: c) Retro reflectors: (iii) Laser head’ s measurement receiver . (iv) Measurement display .

6. TWO FREQUENCY LASER SOURCE Ø It is generally He-Ne type that generates stable coherent light beam of two frequencies. one polarized vertically and another horizontally relative to the plane of the mounting feet. Ø Laser oscillates at two slightly different frequencies by a cylindrical permanent magnet around the cavity. Ø The two components of frequencies are distinguishable by their opposite circular polarization.

8. To avoid attenuation it is essential that the beam splitters must be oriented so that the reflected beam forms a right angle with the transmitted beam.

10. These are actually just flat mirrors but having absolutely flat and very high reflectivity.

14. Retro reflector for this instrument is a cube corner.

16. Its operation same as standard interferometer.

18. Easy installation

20. SCHEMATIC ARRANGEMENT OF LASER INTERFEROMETER

21. Two-frequency zeeman laser generates light of two slightly different frequencies with opposite circular polarisation. These beams get split up by beam splitter B One part travels towards B and from there to external cube corner here the displacement is to Be measured. This interferometer uses cube corner reflectors which reflect light parallel to its angle of incidence. Beam splitter B2 optically separates the frequency J which alone is sent to the movable cube corner reflector.

22. Principle of Michelson Interferometer Albert Michelson (1852~1931) the first American scientist to receive a Nobel prize, invented the optical interferometer. The Michelson interferometer has been widely used for over a century to make precise measurements of wavelengths and distances. Albert Michelson

23. Principle of Michelson Interferometer Michelson Interferometer Separation Recombination Interference A Michelson Interferometer for use on an optical table

24. Principle of Michelson Interferometer Analyzing Michelson Interferometer The central spot in the fringe pattern alternates between bright and dark when Mirror M2 moves. If we can know the spacing distance of M2 betweentwo sequent central bright spots and the number of central bright spots appeared, then we can calculate how long M2 moved. Photograph of the interference fringes produced by a Michelson interferometer.

25. MICHELSON INTERFEROMETER

27. Principle of Heterodyne Laser interferometer Doppler Effect: The change of frequency when a source moves relative to an observer. We can get the velocity of an object by measure the frequency change between incident laser wave and reflected laser wave.

28. Applications Measurement of Distance 1) frequency stabilized He-Ne laser tube 2) combination of beam-splitter and retroreflector 3) a moving retroreflector 4) detection electronics` Aerotech’s LZR3000 Series Laser Interferometer System

29. Applications Other Applications Measure angles, flatness, straightness, velocity and vibrations, etc. Rearrangements of the light paths

31. http://www.renishaw.com/en/interferometry-explained--7854

32. http://en.wikipedia.org/wiki/Michelson_interferometer

33. http://en.wikipedia.org/wiki/Interferometry