Advanced analytical
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An interferometer is an optical device that uses the phenomenon of interference to combine or split light beams. It splits an input light beam into separate paths using a beam splitter, exposes one or both beams to external influences, then recombines the beams to form an interference pattern of fringes. A Michelson interferometer specifically produces interference by splitting a monochromatic light beam such that one beam reflects off a fixed mirror while the other reflects off a movable mirror, and the reflected beams interfere when recombined. By changing the position of the movable mirror, different path lengths can be created, resulting in constructive or destructive interference that appears as light and dark concentric rings in the projected interference pattern.
Advanced analytical
- 1. Presented by • Ali zia (Bsf1702570) • Hafiz Muhammad Ubaid Arif (Bsf1702533) • Muhammad Tahir Mehmood (Bsf1702589) • Muhammad Mashhood (Bsf1601428) • Jafar Nadeem Bhatti (Bsf1702454)
- 3. Interferometer • An interferometer is an optical device which utilizes the concept of interference. Typically it starts with same input beams, split it into separate beams with some kind of beam splitter(a partially transmissive mirror), possibly exposes some of these beams to some external influence, and then combine the beams on a surface to visualize the pattern of fringes being formed.
- 4. Principle • If two rays of same wavelength meet at some point mutual interference occurs & mutual interference depends upon phase of two waves at their meeting points. • If two rays are in same phase then the resulting intensity will be the sum of two intensities. • If two rays are out of phase the resulting intensity will be the difference of two intensities. • If two rays having the same amplitude are in same phase, then the resultant will be twice and result will be bright spot and vice versa.
- 5. Typical Interferometer • The expanded beam exiting from the light source is divided by a Beam splitter into two beams. • One beam is reflected from the Reference Mirror, and the other one from the Sample. • These two beams are recombined by the Beam splitter to interfere. • The imaging lens images the interferogram onto the CCD camera.
- 6. Optical Path Difference (OPD) - difference in optical path lengths that beams travel in Reference and Test arms
- 7. Michelson's interferometer • A Michaelson interferometer is a tool to produce interference between two beams of light. • Michelson interferometer produces interference fringes by splitting a beam of monochromatic light such that one beam hits a fixed mirror and the other a movable mirror. When the reflected beams are combined an interference pattern is formed. • To create interference fringes on a detector the path has to be of different lengths or composed of different materials.
- 8. Construction • The main optical path consists of two highly polished mirrors and a plane parallel plate of glass(compensator) and a beam splitter. • sometimes the rear side od the beam splitter is slightly silvered so that coming light is converted into a reflected and transmitted light of equal intensity. • To obtain interference fringes two mirrors are made exactly perpendicular to each other. • Even when these adjustments have been made, fringes will not be seen unless tow important requirements are fulfilled 1. Light must originate from an extended source 2. The light must generally be monochromatic or nearly so.
- 11. Working and interpretations • For certain path lengths the waves are in phase when combined, and constructive interference occurs. • Moving the mirror changes the position at which light interferes constructively or destructively. • The interference pattern is projected onto a surface as a series of concentric rings of light and dark. • With a path difference of an integral of wavelength of light bright fringes appear due to the constructive interference. • With a path difference of odd multiple of half wavelength of light destructive interference pattern or dark bands are formed.
- 12. Interferogram