An interferometer is a scientific instrument used to measure small distances, changes in displacement, or other physical properties by utilizing the interference of waves, typically light or radio waves. The principle behind an interferometer is that when two or more waves of the same frequency are superimposed, they can interfere with each other, either enhancing or canceling out each other’s amplitudes depending on their phase relationship.
There are several types of interferometers, but the most common ones use light (such as laser light) to create interference patterns. When light is split into two or more beams, these beams travel along different paths and are then recombined. If there is a difference in the path length or phase shift between the beams, it will result in a measurable interference pattern (such as dark and light fringes), which can be analyzed to infer very precise measurements.
Some well-known examples of interferometers include:
- Michelson interferometer: Used in experiments to measure the speed of light, and in modern physics experiments like those detecting gravitational waves.
- Fabry-Perot interferometer: Used in spectroscopy to resolve fine details in light spectra.
- Fizeau interferometer: Used for measuring small changes in distance or displacement.
Interferometers are used in many fields, including physics, astronomy, engineering, and even in medical applications like optical coherence tomography.