Interference Flashcards
What is an interferogram?
A plot of the output of the interferometer as the path difference is changed
What can you use an interferometer for?
- To measure lengths with very high accuracy.
- Measure position very precisely.
- Measure the movement of an object very accurately.
- Use it as a Fourier transform spectrometer to obtain high-resolution spectra.
Describe the positions of the mirrors in the Michelson interferometer to produce circular fringes of constant inclination.
The mirrors are parallel (optically).
Describe the positions of the mirrors in the Michelson interferometer to produce straight Fizeau fringes.
With inclined mirrors.
What are the components of the Michelson Interferometer?
Diffuse source, beam-splitter, two mirrors and a compensating plate.
What are the fringes called of constant optical thickness and how are they obtained?
Fizeau’s fringes obtained from an air wedge.
What are examples of fringes of constant inclination?
Soap bubble, Oil on water, Beetle’s backs.
How are thin film fringes produced?
Formed by the interference between light reflected from the top and bottom of a film- division of amplitude.
What variation on Young’s slit experiment demonstrates that light reflected from a more dense medium undergoes a phase change of pi.
Lloyd’s mirror.
What does increasing the number of lines of a grating do to the inference pattern?
It creates a sharper interference pattern.
What happens in a spectrometer if you replace the prism with a diffraction gating?
The grating with spread out the spectrum more widely than the prism does.
What can be deduced from Young’s slit experiment?
By measuring the distance between neighbouring fringes, the wavelength.
What is coherence?
Coherence in waves is when when they have a constant relative phase.
What is coherence length?
Describes the propagating distance of a wave where it maintains a specific phase.
What do waves need to have to interfere with each other?
They need to have a constant phase relationship and be monochromatic.
