Optical fiber interferometer has been developed for over
a hundred years and is used as precision metrology that is widely used in the
optical system for extremely accurate measurements for a variety of physical
quantities in laboratories as well as in industry fields. The base of optical
interferometry technology lies in the interference of light beams that are
launched from another monochromatic source, same light source, or laser source.
It propagates through space or dielectric mediums such as glass waveguides with
different optical paths. It then arrives simultaneously at a point in space or
on the surface of an object. Hence the light intensity will differ periodically
with the optical path difference, which is the optical phase difference,
between the beams. This is a much-known process of light interference.
In the wavelength scale of the optical light source, a very small change
in the optical path difference can induce an obvious and measurable change in
the intensity of the interference light. So, by measuring the changes of
interference light intensity, one can obtain information regarding the changes
of optical paths in an optical measurement system. The optical interferometer
is built as an instrument due to this mechanism and for accurate measurements
of many physical quantities, such as the displacement, velocity, and distance,
as well as for tests of optical systems it is widely used.
Optical interferometry technology has made great progress due to huge
developments of laser and fiber optic technologies and has also evolved from
classical bulk optics to fiber optics. Applications of the optical
interferometers have been expanded to areas such as underwater acoustic
detections, voltage and current measurements inside electric power systems, and
biomedical pressure monitoring in living bodies but everything depends on
fiber-optic technologies.
One major application of the optical interferometer is that it is used as
the optical interferometer sensor for the detection of unknown and uncontrolled
physical parameters. Fiber-optic-based interferometers use optical fibers as
sensor light carriers. From fiber-connected transducers or directly from fibers
it obtains the detection information.
In general, the preparation of optical power meters and
fiber-optic transducers/sensors is done from totally dielectric materials that
are chemically inert and completely immune to electromagnetic interference
(EMI).
